Peptide name : Protein farnesyltransferase subunit beta

Source/Organism : Rat

Linear/Cyclic : Not found

Chirality : Not found

Peptide length: 437

C-terminal modification: Not found

N-terminal modification : Free

Non-natural peptide information: None

Assay type : Formate dehydrogenase–coupled PDF assay, Thymidine incorporation assay

Assay time : 48h

Activity : IC50 : > 250μM

Cell line : HEK293

Cancer type : Renal cancer

Other activity : Not found

Amino acid composition bar chart :

Molecular mass : 48672.9545 Dalton

Aliphatic index : 0.839

Instability index : 49.6298

Hydrophobicity (GRAVY) : -0.147

Isoelectric point : 5.5564

Charge (pH 7) : -14.117

Aromaticity : 0.100

Molar extinction coefficient (cysteine, cystine): (72310, 73310)

Hydrophobic/hydrophilic ratio : 1.185

hydrophobic moment : 0.0395

Missing amino acid : None

Most occurring amino acid : L

Most occurring amino acid frequency : 49

Least occurring amino acid : W

Least occurring amino acid frequency : 8

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

SMILES Notation: CC[C@H](C)[C@H](NC(=O)CNC(=O)CNC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CS)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](C)NC(=O)[C@@H](NC(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](C)NC(=O)[C@@H](NC(=O)CNC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CC(=O)O)NC(=O)[C@@H]1CCCN1C(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](CC(N)=O)NC(=O)[C@@H](NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CO)NC(=O)[C@H](C)NC(=O)[C@@H](NC(=O)[C@H](CO)NC(=O)[C@H](C)NC(=O)[C@H](C)NC(=O)[C@H](CS)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](C)NC(=O)[C@H](CO)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@@H](NC(=O)[C@H](CC(=O)O)NC(=O)[C@@H](NC(=O)[C@H](CCC(=O)O)NC(=O)CNC(=O)CNC(=O)[C@@H](NC(=O)[C@H](Cc1c[nH]cn1)NC(=O)[C@H](CCSC)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](CO)NC(=O)CNC(=O)[C@H](CC(=O)O)NC(=O)[C@@H]1CCCN1C(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CCCCN)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CO)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](CC(C)C)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](CC(C)C)NC(=O)[C@H](CCCCN)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CC(N)=O)NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](C)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@@H](NC(=O)CNC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](CS)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](C)NC(=O)[C@H](CC(N)=O)NC(=O)[C@@H](NC(=O)[C@H](C)NC(=O)[C@H](C)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@@H](NC(=O)[C@@H]1CCCN1C(=O)[C@H](C)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](Cc1c[nH]cn1)NC(=O)[C@@H]1CCCN1C(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](CCC(N)=O)NC(=O)CNC(=O)[C@@H]1CCCN1C(=O)CNC(=O)CNC(=O)CNC(=O)[C@H](Cc1ccccc1)NC(=O)CNC(=O)CNC(=O)[C@H](CC(=O)O)NC(=O)[C@@H]1CCCN1C(=O)[C@H](CO)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CS)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CS)NC(=O)[C@@H](NC(=O)[C@H](CC(=O)O)NC(=O)[C@@H](NC(=O)[C@H](C)NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](CCC(N)=O)NC(=O)[C@@H]1CCCN1C(=O)[C@@H](NC(=O)[C@@H]1CCCN1C(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CO)NC(=O)[C@H](Cc1c[nH]cn1)NC(=O)[C@H](CC(C)C)NC(=O)[C@@H](NC(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](CS)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)[C@@H]1CCCN1C(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CO)NC(=O)[C@H](C)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CS)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](C)NC(=O)[C@H](CC(=O)O)NC(=O)[C@@H](NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CC(C)C)NC(=O)CNC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CCCCN)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](Cc1c[nH]cn1)NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](Cc1c[nH]cn1)NC(=O)[C@H](CCCCN)NC(=O)[C@H](CCC(=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](CC(C)C)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@@H]1CCCN1C(=O)[C@@H](NC(=O)[C@H](CC(C)C)NC(=O)[C@H](Cc1c[nH]cn1)NC(=O)[C@H](CC(N)=O)NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](CCCCN)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](CO)NC(=O)[C@H](CO)NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@@H](NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@@H](NC(=O)[C@H](CCCCN)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@@H](NC(=O)[C@H](CCCCN)NC(=O)[C@H](C)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@@H](NC(=O)[C@H](CO)NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](CCC(=O)O)NC(=O)[C@@H](NC(=O)[C@H](CO)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CCC(N)=O)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](C)NC(=O)[C@H](Cc1c[nH]cn1)NC(=O)[C@H](CCC(=O)O)NC(=O)[C@@H]1CCCN1C(=O)[C@H](CCCNC(=N)N)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](CO)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](CC(C)C)NC(=O)[C@@H]1CCCN1C(=O)[C@H](CCC(=O)O)NC(=O)[C@H](CO)NC(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)[C@@H](NC(=O)[C@@H]1CCCN1C(=O)[C@H](CO)NC(=O)[C@H](CO)NC(=O)[C@H](CO)NC(=O)[C@@H]1CCCN1C(=O)[C@@H]1CCCN1C(=O)[C@H](CS)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@@H](NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](CO)NC(=O)[C@H](CO)NC(=O)[C@H](CO)NC(=O)[C@H](CO)NC(=O)[C@H](C)NC(=O)[C@@H](N)CCSC)[C@@H](C)O)C(C)C)C(C)C)[C@@H](C)O)C(C)C)[C@@H](C)O)[C@@H](C)CC)C(C)C)[C@@H](C)CC)C(C)C)C(C)C)C(C)C)[C@@H](C)O)[C@@H](C)CC)[C@@H](C)CC)[C@@H](C)CC)C(C)C)[C@@H](C)O)C(C)C)[C@@H](C)O)C(C)C)[C@@H](C)CC)[C@@H](C)CC)[C@@H](C)O)C(C)C)[C@@H](C)CC)C(C)C)C(C)C)C(C)C)C(C)C)[C@@H](C)O)[C@@H](C)CC)[C@@H](C)CC)[C@@H](C)O)[C@@H](C)O)[C@@H](C)CC)C(=O)NCC(=O)NCC(=O)N[C@H](C(=O)N1CCC[C@H]1C(=O)NCC(=O)N[C@@H](CCSC)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](C)C(=O)N[C@@H](Cc1c[nH]cn1)C(=O)NCC(=O)NCC(=O)N[C@@H](Cc1ccc(O)cc1)C(=O)N[C@H](C(=O)N[C@@H](Cc1ccccc1)C(=O)N[C@@H](CS)C(=O)NCC(=O)N[C@@H](CC(C)C)C(=O)N[C@@H](C)C(=O)N[C@@H](C)C(=O)N[C@@H](CC(C)C)C(=O)N[C@H](C(=O)N[C@H](C(=O)N[C@@H](CC(C)C)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CCC(=O)O)C(=O)N[C@@H](CCCNC(=N)N)C(=O)N[C@@H]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1 : 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

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5 : 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

6 : 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

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

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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 : cDNA cloning and expression of the peptide-binding beta subunit of rat p21ras farnesyltransferase, the counterpart of yeast DPR1/RAM1.

Doi : https://doi.org/10.1016/0092-8674(91)90622-6

Abstract : Protein farnesyltransferase is a heterodimeric enzyme that attaches a farnesyl group to cysteine in ras proteins and other membrane-associated proteins. The beta subunit contains the recognition site for the peptide substrates, but is inactive in the absence of the alpha subunit. A cloned cDNA for the rat beta subunit predicts a protein of 437 amino acids whose mRNA is present in many tissues. Transfection of the beta subunit cDNA produced farnesyltransferase activity in human kidney cells, but only when it was transfected together with a cDNA encoding part of the alpha subunit. Each of the subunits appeared to be unstable in the transfected cells unless the other subunit was present. The rat beta subunit shows 37% sequence identity with the protein encoded by the yeast DPR1/RAM1 gene, indicating that DPR1/RAM1 is the yeast counterpart of the peptide-binding subunit of the mammalian farnesyltransferase.

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 : 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 : 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 : 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 : W-band time-resolved electron paramagnetic resonance study of light-induced spin dynamics in copper-nitroxide-based switchable molecular magnets.

Doi : https://doi.org/10.1021/ja306467e

Abstract : Molecular magnets Cu(hfac)(2)L(R) represent a new type of photoswitchable materials based on exchange-coupled clusters of copper(II) with stable nitroxide radicals. It was found recently that the photoinduced spin state of these compounds is metastable on the time scale of hours at cryogenic temperatures, similar to the light-induced excited spin state trapping phenomenon well-known for many spin-crossover compounds. Our previous studies have shown that electron paramagnetic resonance (EPR) in continuous wave (CW) mode allows for studying the light-induced spin state conversion and relaxation in the Cu(hfac)(2)L(R) family. However, light-induced spin dynamics in these compounds has not been studied on the sub-second time scale so far. In this work we report the first time-resolved (TR) EPR study of light-induced spin state switching and relaxation in Cu(hfac)(2)L(R) with nanosecond temporal resolution. To enhance spectral resolution we used high-frequency TR EPR at W-band (94 GHz). We first discuss the peculiarities of applying TR EPR to the solid-phase compounds Cu(hfac)(2)L(R) at low (liquid helium) temperatures and approaches developed for photoswitching/relaxation studies. Then we analyze the kinetics of the excited spin state at T = 5-21 K. It has been found that the photoinduced spin state is formed at time delays shorter than 100 ns. It has also been found that the observed relaxation of the excited state is exponential on the nanosecond time scale, with the decay rate depending linearly on temperature. We propose and discuss possible mechanisms of these processes and correlate them with previously obtained CW EPR data.

Paper title : Discovery of C-imidazole azaheptapyridine FPT inhibitors.

Doi : https://doi.org/10.1016/j.bmcl.2009.12.013

Abstract : The discovery of C-linked imidazole azaheptapyridine bridgehead FPT inhibitors is described. This novel class of compounds are sub nM FPT enzyme inhibitors with potent cellular inhibitory activities. This series also has reduced hERG activity versus previous N-linked imidazole series. X-ray of compound 10a bound to FTase revealed strong interaction between bridgehead imidazole 3N with catalytic zinc atom.

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 : 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 : 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 : 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 : 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 : The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).

Doi : https://doi.org/10.1101/gr.2596504

Abstract : The National Institutes of Health's Mammalian Gene Collection (MGC) project was designed to generate and sequence a publicly accessible cDNA resource containing a complete open reading frame (ORF) for every human and mouse gene. The project initially used a random strategy to select clones from a large number of cDNA libraries from diverse tissues. Candidate clones were chosen based on 5'-EST sequences, and then fully sequenced to high accuracy and analyzed by algorithms developed for this project. Currently, more than 11,000 human and 10,000 mouse genes are represented in MGC by at least one clone with a full ORF. The random selection approach is now reaching a saturation point, and a transition to protocols targeted at the missing transcripts is now required to complete the mouse and human collections. Comparison of the sequence of the MGC clones to reference genome sequences reveals that most cDNA clones are of very high sequence quality, although it is likely that some cDNAs may carry missense variants as a consequence of experimental artifact, such as PCR, cloning, or reverse transcriptase errors. Recently, a rat cDNA component was added to the project, and ongoing frog (Xenopus) and zebrafish (Danio) cDNA projects were expanded to take advantage of the high-throughput MGC pipeline.

Paper title : Structural basis for binding and selectivity of antimalarial and anticancer ethylenediamine inhibitors to protein farnesyltransferase.

Doi : https://doi.org/10.1016/j.chembiol.2009.01.014

Abstract : Protein farnesyltransferase (FTase) catalyzes an essential posttranslational lipid modification of more than 60 proteins involved in intracellular signal transduction networks. FTase inhibitors have emerged as a significant target for development of anticancer therapeutics and, more recently, for the treatment of parasitic diseases caused by protozoan pathogens, including malaria (Plasmodium falciparum). We present the X-ray crystallographic structures of complexes of mammalian FTase with five inhibitors based on an ethylenediamine scaffold, two of which exhibit over 1000-fold selective inhibition of P. falciparum FTase. These structures reveal the dominant determinants in both the inhibitor and enzyme that control binding and selectivity. Comparison to a homology model constructed for the P. falciparum FTase suggests opportunities for further improving selectivity of a new generation of antimalarial inhibitors.