2dh4
From Proteopedia
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Geranylgeranyl pyrophosphate synthase
Overview
Geranylgeranyl pyrophosphate synthase (GGPPs) catalyzes a condensation, reaction of farnesyl pyrophosphate with isopentenyl pyrophosphate to, generate C(20) geranylgeranyl pyrophosphate, which is a precursor for, carotenoids, chlorophylls, geranylgeranylated proteins, and archaeal, ether-linked lipid. For short-chain trans-prenyltransferases that, synthesize C(10)-C(25) products, bulky amino acid residues generally, occupy the fourth or fifth position upstream from the first DDXXD motif to, block further elongation of the final products. However, the short-chain, type-III GGPPs in eukaryotes lack any large amino acid at these positions., In this study, the first structure of type-III GGPPs from Saccharomyces, cerevisiae has been determined to 1.98 A resolution. The structure is, composed entirely of 15 alpha-helices joined by connecting loops and is, arranged with alpha-helices around a large central cavity. Distinct from, other known structures of trans-prenyltransferases, the N-terminal 17, amino acids (9-amino acid helix A and the following loop) of this GGPPs, protrude from the helix core into the other subunit and contribute to the, tight dimer formation. Deletion of the first 9 or 17 amino acids caused, the dissociation of dimer into monomer, and the Delta(1-17) mutant showed, abolished enzyme activity. In each subunit, an elongated hydrophobic, crevice surrounded by D, F, G, H, and I alpha-helices contains two DDXXD, motifs at the top for substrate binding with one Mg(2+) coordinated by, Asp(75), Asp(79), and four water molecules. It is sealed at the bottom, with three large residues of Tyr(107), Phe(108), and His(139). Compared, with the major product C(30) synthesized by mutant H139A, the products, generated by mutant Y107A and F108A are predominantly C(40) and C(30), respectively, suggesting the most important role of Tyr(107) in, determining the product chain length.
About this Structure
2DH4 is a Single protein structure of sequence from Saccharomyces cerevisiae with MG as ligand. Active as Farnesyltranstransferase, with EC number 2.5.1.29 Full crystallographic information is available from OCA.
Reference
Crystal structure of type-III geranylgeranyl pyrophosphate synthase from Saccharomyces cerevisiae and the mechanism of product chain length determination., Chang TH, Guo RT, Ko TP, Wang AH, Liang PH, J Biol Chem. 2006 May 26;281(21):14991-5000. Epub 2006 Mar 22. PMID:16554305
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