Peptide name : Protein farnesyltransferase/geranylgeranyltransferase type-1 subunit alpha

Source/Organism : Rat

Linear/Cyclic : Cyclic

Chirality : Not found

Peptide length: 377

C-terminal modification: Cyclic

N-terminal modification : Free

Non-natural peptide information: None

Assay type : Not specified

Assay time : Not found

Activity : Not found

Cell line : Not found

Cancer type : Not found

Other activity : Not found

Amino acid composition bar chart :

Molecular mass : 44048.7797 Dalton

Aliphatic index : 0.840

Instability index : 59.6194

Hydrophobicity (GRAVY) : -0.695

Isoelectric point : 4.8255

Charge (pH 7) : -22.6367

Aromaticity : 0.098

Molar extinction coefficient (cysteine, cystine): (81820, 81945)

Hydrophobic/hydrophilic ratio : 0.83902439

hydrophobic moment : -0.117

Missing amino acid : None

Most occurring amino acid : L

Most occurring amino acid frequency : 37

Least occurring amino acid : C

Least occurring amino acid frequency : 2

Secondary structure fraction (Helix, Turn, Sheet): (0.3, 0.2, 0.3)

SMILES Notation: CC[C@H](C)[C@H](NC(=O)CNC(=O)[C@H](CCCCN)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)[C@H](C)NC(=O)[C@H](CO)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](Cc1c[nH]cn1)NC(=O)[C@@H]1CCCN1C(=O)[C@@H](NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CCCCN)NC(=O)[C@@H](NC(=O)[C@H](CCSC)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CC(C)C)NC(=O)[C@@H](NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@@H](NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CC(C)C)NC(=O)[C@@H](NC(=O)[C@H](C)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CO)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)CNC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](CO)NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](Cc1c[nH]cn1)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)[C@@H](NC(=O)[C@H](CO)NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@@H](NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CCCCN)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CC(=O)O)NC(=O)[C@@H](NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](Cc1c[nH]cn1)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)[C@H](C)NC(=O)[C@H](Cc1c[nH]cn1)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](CCCCN)NC(=O)[C@H](C)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](CC(C)C)NC(=O)[C@@H](NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](C)NC(=O)[C@@H](NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CO)NC(=O)[C@@H]1CCCN1C(=O)[C@H](CC(=O)O)NC(=O)[C@H](CCCCN)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@@H](NC(=O)[C@H](CC(C)C)NC(=O)[C@@H](NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](Cc1c[nH]cn1)NC(=O)[C@H](Cc1c[nH]cn1)NC(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)[C@@H](NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](CCCCN)NC(=O)[C@@H]1CCCN1C(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](C)NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](CCSC)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CCCCN)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CO)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CC(C)C)NC(=O)[C@@H](NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](Cc1c[nH]cn1)NC(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](C)NC(=O)[C@H](C)NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@@H](NC(=O)[C@H](C)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@@H](NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CCCCN)NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](C)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CO)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CC(C)C)NC(=O)[C@@H](NC(=O)[C@H](C)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@@H](NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](CCCCN)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CO)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](CCC(N)=O)NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@@H]1CCCN1C(=O)[C@H](CO)NC(=O)[C@@H]1CCCN1C(=O)CNC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@@H]1CCCN1C(=O)[C@@H](NC(=O)[C@@H]1CCCN1C(=O)[C@H](CC(=O)O)NC(=O)[C@@H](NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](C)NC(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](C)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](CC(C)C)NC(=O)[C@@H](NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@@H](NC(=O)[C@@H]1CCCN1C(=O)[C@H](CO)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CO)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](Cc1ccccc1)NC(=O)CNC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CCSC)NC(=O)[C@@H]1CCCN1C(=O)[C@H](CO)NC(=O)[C@H](C)NC(=O)[C@H](C)NC(=O)[C@H](C)NC(=O)[C@H](CCC(=O)O)NC(=O)CNC(=O)[C@H](C)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](C)NC(=O)[C@H](C)NC(=O)[C@H](CCSC)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@@H]1CCCN1C(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](C)NC(=O)[C@@H]1CCCN1C(=O)[C@@H]1CCCN1C(=O)[C@@H]1CCCN1C(=O)[C@@H]1CCCN1C(=O)[C@@H]1CCCN1C(=O)[C@@H]1CCCN1C(=O)[C@@H]1CCCN1C(=O)[C@@H]1CCCN1C(=O)[C@@H]1CCCN1C(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@@H]1CCCN1C(=O)[C@H](CCC(N)=O)NC(=O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1 : Long SB, et al. Cocrystal structure of protein farnesyltransferase complexed with a farnesyl diphosphate substrate. Biochemistry. 1998; 37:9612-8. doi: 10.1021/bi980708e

2 : Reid TS and Beese LS. Crystal structures of the anticancer clinical candidates R115777 (Tipifarnib) and BMS-214662 complexed with protein farnesyltransferase suggest a mechanism of FTI selectivity. Biochemistry. 2004; 43:6877-84. doi: 10.1021/bi049723b

3 : Reid TS, et al. Crystallographic analysis of CaaX prenyltransferases complexed with substrates defines rules of protein substrate selectivity. J Mol Biol. 2004; 343:417-33. doi: 10.1016/j.jmb.2004.08.056

4 : Long SB, et al. The basis for K-Ras4B binding specificity to protein farnesyltransferase revealed by 2 A resolution ternary complex structures. Structure. 2000; 8:209-22. doi: 10.1016/s0969-2126(00)00096-4

5 : Strickland CL, et al. Tricyclic farnesyl protein transferase inhibitors: crystallographic and calorimetric studies of structure-activity relationships. J Med Chem. 1999; 42:2125-35. doi: 10.1021/jm990030g

6 : Turek-Etienne TC, et al. Biochemical and structural studies with prenyl diphosphate analogues provide insights into isoprenoid recognition by protein farnesyl transferase. Biochemistry. 2003; 42:3716-24. doi: 10.1021/bi0266838

7 : Long SB, et al. Reaction path of protein farnesyltransferase at atomic resolution. Nature. 2002; 419:645-50. doi: 10.1038/nature00986

8 : Taylor JS, et al. Structure of mammalian protein geranylgeranyltransferase type-I. EMBO J. 2003; 22:5963-74. doi: 10.1093/emboj/cdg571

9 : Long SB, et al. The crystal structure of human protein farnesyltransferase reveals the basis for inhibition by CaaX tetrapeptides and their mimetics. Proc Natl Acad Sci U S A. 2001; 98:12948-53. doi: 10.1073/pnas.241407898

10 : DeGraw AJ, et al. Caged protein prenyltransferase substrates: tools for understanding protein prenylation. Chem Biol Drug Des. 2008; 72:171-81. doi: 10.1111/j.1747-0285.2008.00698.x

11 : Nguyen UT, et al. Analysis of the eukaryotic prenylome by isoprenoid affinity tagging. Nat Chem Biol. 2009; 5:227-35. doi: 10.1038/nchembio.149

12 : Stigter EA, et al. Development of selective, potent RabGGTase inhibitors. J Med Chem. 2012; 55:8330-40. doi: 10.1021/jm300624s

13 : Park HW, et al. Crystal structure of protein farnesyltransferase at 2.25 angstrom resolution. Science. 1997; 275:1800-4. doi: 10.1126/science.275.5307.1800

14 : Gwaltney SL, et al. Aryl tetrahydropyridine inhibitors of farnesyltransferase: glycine, phenylalanine and histidine derivatives. Bioorg Med Chem Lett. 2003; 13:1359-62. doi: 10.1016/s0960-894x(03)00095-7

15 : Dunten P, et al. Protein farnesyltransferase: structure and implications for substrate binding. Biochemistry. 1998; 37:7907-12. doi: 10.1021/bi980531o

16 : Strickland CL, et al. Crystal structure of farnesyl protein transferase complexed with a CaaX peptide and farnesyl diphosphate analogue. Biochemistry. 1998; 37:16601-11. doi: 10.1021/bi981197z

17 : Chen WJ, et al. Cloning and expression of a cDNA encoding the alpha subunit of rat p21ras protein farnesyltransferase. Proc Natl Acad Sci U S A. 1991; 88:11368-72. doi: 10.1073/pnas.88.24.11368

Paper title : Cocrystal structure of protein farnesyltransferase complexed with a farnesyl diphosphate substrate.

Doi : https://doi.org/10.1021/bi980708e

Abstract : Protein farnesyltransferase (FTase) catalyzes the transfer of the hydrophobic farnesyl group from farnesyl diphosphate (FPP) to cellular proteins such as Ras at a cysteine residue near their carboxy-terminus. This process is necessary for the subcellular localization of these proteins to the plasma membrane and is required for the transforming activity of oncogenic variants of Ras, making FTase a prime target for anticancer therapeutics. The high-resolution crystal structure of rat FTase was recently determined, and we present here the X-ray crystal structure of the first complex of FTase with a FPP substrate bound at the active site. The isoprenoid moiety of FPP binds in an extended conformation in a hydrophobic cavity of the beta subunit of the FTase enzyme, and the diphosphate moiety binds to a positively charged cleft at the top of this cavity near the subunit interface. The observed location of the FPP molecule is consistent with mutagenesis data. This binary complex of FTase with FPP leads us to suggest a "molecular ruler" hypothesis for isoprenoid substrate specificity, where the depth of the hydrophobic binding cavity acts as a ruler discriminating between isoprenoids of differing lengths. Although other length isoprenoids may bind in the cavity, only the 15-carbon farnesyl moiety binds with its C1 atom in register with a catalytic zinc ion as required for efficient transfer to the Ras substrate.

Paper title : Crystal structures of the anticancer clinical candidates R115777 (Tipifarnib) and BMS-214662 complexed with protein farnesyltransferase suggest a mechanism of FTI selectivity.

Doi : https://doi.org/10.1021/bi049723b

Abstract : The search for new cancer therapeutics has identified protein farnesyltransferase (FTase) as a promising drug target. This enzyme attaches isoprenoid lipids to signal transduction proteins involved in growth and differentiation. The two FTase inhibitors (FTIs), R115777 (tipifarnib/Zarnestra) and BMS-214662, have undergone evaluation as cancer therapeutics in phase I and II clinical trials. R115777 has been evaluated in phase III clinical trials and shows indications for the treatment of blood and breast malignancies. Here we present crystal structures of R115777 and BMS-214662 complexed with mammalian FTase. These structures illustrate the molecular mechanism of inhibition and selectivity toward FTase over the related enzyme, protein geranylgeranyltransferase type I (GGTase-I). These results, combined with previous biochemical and structural analyses, identify features of FTase that could be exploited to modulate inhibitor potency and specificity and should aid in the continued development of FTIs as therapeutics for the treatment of cancer and parasitic infections.

Paper title : Crystallographic analysis of CaaX prenyltransferases complexed with substrates defines rules of protein substrate selectivity.

Doi : https://doi.org/10.1016/j.jmb.2004.08.056

Abstract : Post-translational modifications are essential for the proper function of many proteins in the cell. The attachment of an isoprenoid lipid (a process termed prenylation) by protein farnesyltransferase (FTase) or geranylgeranyltransferase type I (GGTase-I) is essential for the function of many signal transduction proteins involved in growth, differentiation, and oncogenesis. FTase and GGTase-I (also called the CaaX prenyltransferases) recognize protein substrates with a C-terminal tetrapeptide recognition motif called the Ca1a2X box. These enzymes possess distinct but overlapping protein substrate specificity that is determined primarily by the sequence identity of the Ca1a2X motif. To determine how the identity of the Ca1a2X motif residues and sequence upstream of this motif affect substrate binding, we have solved crystal structures of FTase and GGTase-I complexed with a total of eight cognate and cross-reactive substrate peptides, including those derived from the C termini of the oncoproteins K-Ras4B, H-Ras and TC21. These structures suggest that all peptide substrates adopt a common binding mode in the FTase and GGTase-I active site. Unexpectedly, while the X residue of the Ca1a2X motif binds in the same location for all GGTase-I substrates, the X residue of FTase substrates can bind in one of two different sites. Together, these structures outline a series of rules that govern substrate peptide selectivity; these rules were utilized to classify known protein substrates of CaaX prenyltransferases and to generate a list of hypothetical substrates within the human genome.

Paper title : The basis for K-Ras4B binding specificity to protein farnesyltransferase revealed by 2 A resolution ternary complex structures.

Doi : https://doi.org/10.1016/s0969-2126(00)00096-4

Abstract : BACKGROUND: The protein farnesyltransferase (FTase) catalyzes addition of the hydrophobic farnesyl isoprenoid to a cysteine residue fourth from the C terminus of several protein acceptors that are essential for cellular signal transduction such as Ras and Rho. This addition is necessary for the biological function of the modified proteins. The majority of Ras-related human cancers are associated with oncogenic variants of K-RasB, which is the highest affinity natural substrate of FTase. Inhibition of FTase causes regression of Ras-mediated tumors in animal models. RESULTS: We present four ternary complexes of rat FTase co-crystallized with farnesyl diphosphate analogs and K-Ras4B peptide substrates. The Ca(1)a(2)X portion of the peptide substrate binds in an extended conformation in the hydrophobic cavity of FTase and coordinates the active site zinc ion. These complexes offer the first view of the polybasic region of the K-Ras4B peptide substrate, which confers the major enhancement of affinity of this substrate. The polybasic region forms a type I beta turn and binds along the rim of the hydrophobic cavity. Removal of the catalytically essential zinc ion results in a dramatically different peptide conformation in which the Ca(1)a(2)X motif adopts a beta turn. A manganese ion binds to the diphosphate mimic of the farnesyl diphosphate analog. CONCLUSIONS: These ternary complexes provide new insight into the molecular basis of peptide substrate specificity, and further define the roles of zinc and magnesium in the prenyltransferase reaction. Zinc is essential for productive Ca(1)a(2)X peptide binding, suggesting that the beta-turn conformation identified in previous nuclear magnetic resonance (NMR) studies reflects a state in which the cysteine is not coordinated to the zinc ion. The structural information presented here should facilitate structure-based design and optimization of inhibitors of Ca(1)a(2)X protein prenyltransferases.

Paper title : Tricyclic farnesyl protein transferase inhibitors: crystallographic and calorimetric studies of structure-activity relationships.

Doi : https://doi.org/10.1021/jm990030g

Abstract : Crystallographic and thermodynamic studies of farnesyl protein transferase (FPT) complexed with novel tricyclic inhibitors provide insights into the observed SAR for this unique class of nonpeptidic FPT inhibitors. The crystallographic structures reveal a binding pattern conserved across the mono-, di-, and trihalogen series. In the complexes, the tricycle spans the FPT active site cavity and interacts with both protein atoms and the isoprenoid portion of bound farnesyl diphosphate. An amide carbonyl, common to the tricyclic compounds described here, participates in a water-mediated hydrogen bond to the protein backbone. Ten high-resolution crystal structures of inhibitors complexed with FPT are reported. Included are crystallographic data for FPT complexed with SCH 66336, a compound currently undergoing clinical trials as an anticancer agent (SCH 66336, 4-[2-[4-(3,10-dibromo-8-chloro-6,11-dihydro-5H-benzo[5, 6]cyclohepta[1, 2-b]pyridin-11-yl)-1-piperidinyl]-2-oxoethyl]-1-piperidinecarbo xamide ). Thermodynamic binding parameters show favorable enthalpies of complex formation and small net entropic contributions as observed for 4-[2-[4-(3,10-dibromo-8-chloro-6,11-dihydro-11H-benzo[5, 6]cyclohepta[1, 2-b]pyridin-11-ylidene)-1-piperidinyl]-2-oxoethyl]pyridine N-oxide where DeltaH degrees bind = -12.5 kcal/mol and TDeltaS degrees bind = -1.5 kcal/mol.

Paper title : Biochemical and structural studies with prenyl diphosphate analogues provide insights into isoprenoid recognition by protein farnesyl transferase.

Doi : https://doi.org/10.1021/bi0266838

Abstract : Protein farnesyl transferase (PFTase) catalyzes the reaction between farnesyl diphosphate and a protein substrate to form a thioether-linked prenylated protein. The fact that many prenylated proteins are involved in signaling processes has generated considerable interest in protein prenyl transferases as possible anticancer targets. While considerable progress has been made in understanding how prenyl transferases distinguish between related target proteins, the rules for isoprenoid discrimination by these enzymes are less well understood. To clarify how PFTase discriminates between FPP and larger prenyl diphosphates, we have examined the interactions between the enzyme and several isoprenoid analogues, GGPP, and the farnesylated peptide product using a combination of biochemical and structural methods. Two photoactive isoprenoid analogues were shown to inhibit yeast PFTase with K(I) values as low as 45 nM. Crystallographic analysis of one of these analogues bound to PFTase reveals that the diphosphate moiety and the two isoprene units bind in the same positions occupied by the corresponding atoms in FPP when bound to PFTase. However, the benzophenone group protrudes into the acceptor protein binding site and prevents the binding of the second (protein) substrate. Crystallographic analysis of geranylgeranyl diphosphate bound to PFTase shows that the terminal two isoprene units and diphosphate group of the molecule map to the corresponding atoms in FPP; however, the first and second isoprene units bulge away from the acceptor protein binding site. Comparison of the GGPP binding mode with the binding of the farnesylated peptide product suggests that the bulkier isoprenoid cannot rearrange to convert to product without unfavorable steric interactions with the acceptor protein. Taken together, these data do not support the "molecular ruler hypotheses". Instead, we propose a "second site exclusion model" in which PFTase binds larger isoprenoids in a fashion that prevents the subsequent productive binding of the acceptor protein or its conversion to product.

Paper title : Reaction path of protein farnesyltransferase at atomic resolution.

Doi : https://doi.org/10.1038/nature00986

Abstract : Protein farnesyltransferase (FTase) catalyses the attachment of a farnesyl lipid group to numerous essential signal transduction proteins, including members of the Ras superfamily. The farnesylation of Ras oncoproteins, which are associated with 30% of human cancers, is essential for their transforming activity. FTase inhibitors are currently in clinical trials for the treatment of cancer. Here we present a complete series of structures representing the major steps along the reaction coordinate of this enzyme. From these observations can be deduced the determinants of substrate specificity and an unusual mechanism in which product release requires binding of substrate, analogous to classically processive enzymes. A structural model for the transition state consistent with previous mechanistic studies was also constructed. The processive nature of the reaction suggests the structural basis for the successive addition of two prenyl groups to Rab proteins by the homologous enzyme geranylgeranyltransferase type-II. Finally, known FTase inhibitors seem to differ in their mechanism of inhibiting the enzyme.

Paper title : Structure of mammalian protein geranylgeranyltransferase type-I.

Doi : https://doi.org/10.1093/emboj/cdg571

Abstract : Protein geranylgeranyltransferase type-I (GGTase-I), one of two CaaX prenyltransferases, is an essential enzyme in eukaryotes. GGTase-I catalyzes C-terminal lipidation of >100 proteins, including many GTP- binding regulatory proteins. We present the first structural information for mammalian GGTase-I, including a series of substrate and product complexes that delineate the path of the chemical reaction. These structures reveal that all protein prenyltransferases share a common reaction mechanism and identify specific residues that play a dominant role in determining prenyl group specificity. This hypothesis was confirmed by converting farnesyltransferase (15-C prenyl substrate) into GGTase-I (20-C prenyl substrate) with a single point mutation. GGTase-I discriminates against farnesyl diphosphate (FPP) at the product turnover step through the inability of a 15-C FPP to displace the 20-C prenyl-peptide product. Understanding these key features of specificity is expected to contribute to optimization of anti-cancer and anti-parasite drugs.

Paper title : The crystal structure of human protein farnesyltransferase reveals the basis for inhibition by CaaX tetrapeptides and their mimetics.

Doi : https://doi.org/10.1073/pnas.241407898

Abstract : Protein farnesyltransferase (FTase) catalyzes the attachment of a farnesyl lipid group to the cysteine residue located in the C-terminal tetrapeptide of many essential signal transduction proteins, including members of the Ras superfamily. Farnesylation is essential both for normal functioning of these proteins, and for the transforming activity of oncogenic mutants. Consequently FTase is an important target for anti-cancer therapeutics. Several FTase inhibitors are currently undergoing clinical trials for cancer treatment. Here, we present the crystal structure of human FTase, as well as ternary complexes with the TKCVFM hexapeptide substrate, CVFM non-substrate tetrapeptide, and L-739,750 peptidomimetic with either farnesyl diphosphate (FPP), or a nonreactive analogue. These structures reveal the structural mechanism of FTase inhibition. Some CaaX tetrapeptide inhibitors are not farnesylated, and are more effective inhibitors than farnesylated CaaX tetrapeptides. CVFM and L-739,750 are not farnesylated, because these inhibitors bind in a conformation that is distinct from the TKCVFM hexapeptide substrate. This non-substrate binding mode is stabilized by an ion pair between the peptide N terminus and the alpha-phosphate of the FPP substrate. Conformational mapping calculations reveal the basis for the sequence specificity in the third position of the CaaX motif that determines whether a tetrapeptide is a substrate or non-substrate. The presence of beta-branched amino acids in this position prevents formation of the non-substrate conformation; all other aliphatic amino acids in this position are predicted to form the non-substrate conformation, provided their N terminus is available to bind to the FPP alpha-phosphate. These results may facilitate further development of FTase inhibitors.

Paper title : Caged protein prenyltransferase substrates: tools for understanding protein prenylation.

Doi : https://doi.org/10.1111/j.1747-0285.2008.00698.x

Abstract : Originally designed to block the prenylation of oncogenic Ras, inhibitors of protein farnesyltransferase currently in preclinical and clinical trials are showing efficacy in cancers with normal Ras. Blocking protein prenylation has also shown promise in the treatment of malaria, Chagas disease and progeria syndrome. A better understanding of the mechanism, targets and in vivo consequences of protein prenylation are needed to elucidate the mode of action of current PFTase (Protein Farnesyltransferase) inhibitors and to create more potent and selective compounds. Caged enzyme substrates are useful tools for understanding enzyme mechanism and biological function. Reported here is the synthesis and characterization of caged substrates of PFTase. The caged isoprenoid diphosphates are poor substrates prior to photolysis. The caged CAAX peptide is a true catalytically caged substrate of PFTase in that it is to not a substrate, yet is able to bind to the enzyme as established by inhibition studies and X-ray crystallography. Irradiation of the caged molecules with 350 nm light readily releases their cognate substrate and their photolysis products are benign. These properties highlight the utility of those analogs towards a variety of in vitro and in vivo applications.

Paper title : Analysis of the eukaryotic prenylome by isoprenoid affinity tagging.

Doi : https://doi.org/10.1038/nchembio.149

Abstract : Protein prenylation is a widespread phenomenon in eukaryotic cells that affects many important signaling molecules. We describe the structure-guided design of engineered protein prenyltransferases and their universal synthetic substrate, biotin-geranylpyrophosphate. These new tools allowed us to detect femtomolar amounts of prenylatable proteins in cells and organs and to identify their cognate protein prenyltransferases. Using this approach, we analyzed the in vivo effects of protein prenyltransferase inhibitors. Whereas some of the inhibitors displayed the expected activities, others lacked in vivo activity or targeted a broader spectrum of prenyltransferases than previously believed. To quantitate the in vivo effect of the prenylation inhibitors, we profiled biotin-geranyl-tagged RabGTPases across the proteome by mass spectrometry. We also demonstrate that sites of active vesicular transport carry most of the RabGTPases. This approach enables a quantitative proteome-wide analysis of the regulation of protein prenylation and its modulation by therapeutic agents.

Paper title : Development of selective, potent RabGGTase inhibitors.

Doi : https://doi.org/10.1021/jm300624s

Abstract : Members of the Ras superfamily of small GTPases are frequently mutated in cancer. Therefore, inhibitors have been developed to address the acitivity of these GTPases by inhibiting their prenylating enzymes FTase, GGTase I, and RabGGTase. In contrast to FTase and GGTase I, only a handful of RabGGTase inhibitors have been developed. The most active RabGGTase inhibitor known until recently was an FTase inhibitor which hit RabGGTase as an off-target. We recently reported our efforts to tune the selectivity of these inhibitors toward RabGGTase. Here we describe an extended set of selective inhibitors. The requirements for selective RabGGTase inhibitors are described in detail, guided by multiple crystal structures. In order to relate in vitro and cellular activity, a high-throughput assay system to detect the attachment of [(3)H]geranylgeranyl groups to Rab was used. Selective RabGGTase inhibition allows the establishment of novel drug discovery programs aimed at the development of anticancer therapeutics.

Paper title : Crystal structure of protein farnesyltransferase at 2.25 angstrom resolution.

Doi : https://doi.org/10.1126/science.275.5307.1800

Abstract : Protein farnesyltransferase (FTase) catalyzes the carboxyl-terminal lipidation of Ras and several other cellular signal transduction proteins. The essential nature of this modification for proper function of these proteins has led to the emergence of FTase as a target for the development of new anticancer therapy. Inhibition of this enzyme suppresses the transformed phenotype in cultured cells and causes tumor regression in animal models. The crystal structure of heterodimeric mammalian FTase was determined at 2.25 angstrom resolution. The structure shows a combination of two unusual domains: a crescent-shaped seven-helical hairpin domain and an alpha-alpha barrel domain. The active site is formed by two clefts that intersect at a bound zinc ion. One cleft contains a nine-residue peptide that may mimic the binding of the Ras substrate; the other cleft is lined with highly conserved aromatic residues appropriate for binding the farnesyl isoprenoid with required specificity.

Paper title : Aryl tetrahydropyridine inhibitors of farnesyltransferase: glycine, phenylalanine and histidine derivatives.

Doi : https://doi.org/10.1016/s0960-894x(03)00095-7

Abstract : Inhibitors of farnesyltransferase are effective against a variety of tumors in mouse models of cancer. Clinical trials to evaluate these agents in humans are ongoing. In our effort to develop new farnesyltransferase inhibitors, we have discovered a series of aryl tetrahydropyridines that incorporate substituted glycine, phenylalanine and histidine residues. The design, synthesis, SAR and biological properties of these compounds will be discussed.

Paper title : Protein farnesyltransferase: structure and implications for substrate binding.

Doi : https://doi.org/10.1021/bi980531o

Abstract : The rat protein farnesyltransferase crystal structure has been solved by multiple isomorphous replacement methods at a resolution of 2.75 A. The three-dimensional structure, together with recent data on the effects of several mutations, led us to propose a model for substrate binding which differs from the model presented by Park et al. based on their independent structure determination [Park, H. -W., Boduluri, S. R., Moomaw, J. F., Casey, P. J., and Beese, L. S. (1997) Science 275, 1800-1804]. Both farnesyl diphosphate and peptide substrates can be accommodated in the hydrophobic active-site barrel, with the sole charged residue inside the barrel, Arg202 of the beta-subunit, forming a salt bridge with the negatively charged carboxy terminus of peptide substrates. Our proposals are based in part on the observation of electron density in the active site which can be modeled as bound farnesyl diphosphate carried through the enzyme purification. In addition, our model explains in structural terms the results of mutational studies which have identified several residues critical for substrate specificity and catalysis.

Paper title : Crystal structure of farnesyl protein transferase complexed with a CaaX peptide and farnesyl diphosphate analogue.

Doi : https://doi.org/10.1021/bi981197z

Abstract : The crystallographic structure of acetyl-Cys-Val-Ile-selenoMet-COOH and alpha-hydroxyfarnesylphosphonic acid (alphaHFP) complexed with rat farnesyl protein transferase (FPT) (space group P61, a = b = 174. 13 A, c = 69.71 A, alpha = beta = 90 degrees, gamma = 120 degrees, Rfactor = 21.8%, Rfree = 29.2%, 2.5 A resolution) is reported. In the ternary complex, the bound substrates are within van der Waals contact of each other and the FPT enzyme. alphaHFP binds in an extended conformation in the active-site cavity where positively charged side chains and solvent molecules interact with the phosphate moiety and aromatic side chains pack adjacent to the isoprenoid chain. The backbone of the bound CaaX peptide adopts an extended conformation, and the side chains interact with both FPT and alphaHFP. The cysteine sulfur of the bound peptide coordinates the active-site zinc. Overall, peptide binding and recognition appear to be dominated by side-chain interactions. Comparison of the structures of the ternary complex and unliganded FPT [Park, H., Boduluri, S., Moomaw, J., Casey, P., and Beese, L. (1997) Science 275, 1800-1804] shows that major rearrangements of several active site side chains occur upon substrate binding.

Paper title : Cloning and expression of a cDNA encoding the alpha subunit of rat p21ras protein farnesyltransferase.

Doi : https://doi.org/10.1073/pnas.88.24.11368

Abstract : The complete amino acid sequence of the alpha subunit of heterodimeric p21ras protein farnesyltransferase from rat has been deduced from the sequence of a cloned cDNA. The cDNA encodes a 377-amino acid protein that migrates on NaDodSO4/polyacrylamide gels identically to the alpha subunit purified from rat brain. When introduced into mammalian cells by transfection, the cDNA for the alpha subunit produced no immunodetectable protein or farnesyltransferase activity unless the cells were simultaneously transfected with a cDNA encoding beta subunit. In light of previous evidence that alpha subunit forms a heterodimer with at least two different beta subunits, current data suggest a mechanism for coordinating amounts of alpha and beta subunits. If an alpha subunit were stable only as a complex with a beta subunit, the number of alpha subunits would be automatically maintained at a level just sufficient to balance all beta subunits, thereby avoiding the potentially toxic overaccumulation of free alpha subunits.