2hs3
T. maritima PurL complexed with FGAR
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OverviewOverview
Formylglycinamide ribonucleotide amidotransferase (FGAR-AT) catalyzes the, ATP-dependent synthesis of formylglycinamidine ribonucleotide (FGAM) from, formylglycinamide ribonucleotide (FGAR) and glutamine in the fourth step, of the purine biosynthetic pathway. FGAR-AT is encoded by the purL gene., Two types of PurL have been detected. The first type, found in eukaryotes, and Gram-negative bacteria, consists of a single 140 kDa polypeptide chain, and is designated large PurL (lgPurL). The second type, small PurL, (smPurL), is found in archaea and Gram-positive bacteria and consists of, an 80 kDa polypeptide chain. SmPurL requires two additional gene products, PurQ and PurS, for activity. PurL is a member of a protein superfamily, that contains a novel ATP-binding domain. Structures of several members of, this superfamily are available in the unliganded form. We determined five, different structures of FGAR-AT from Thermotoga maritima in the presence, of substrates, a substrate analogue, and a product. These complexes have, allowed a detailed description of the novel ATP-binding motif. The, availability of a ternary complex enabled mapping of the active site, thus, identifying potential residues involved in catalysis. The complexes show a, conformational change in the active site compared to the unliganded, structure. Surprising discoveries, an ATP molecule in an auxiliary site of, the protein and the conformational changes associated with its binding, provoke speculation about the regulatory role of the auxiliary site in, formation of the PurLSQ complex as well as the evolutionary relationship, of PurLs from different organisms.
About this StructureAbout this Structure
2HS3 is a Single protein structure of sequence from Thermotoga maritima with PO4 and FGR as ligands. Active as Phosphoribosylformylglycinamidine synthase, with EC number 6.3.5.3 Full crystallographic information is available from OCA.
ReferenceReference
Complexed structures of formylglycinamide ribonucleotide amidotransferase from Thermotoga maritima describe a novel ATP binding protein superfamily., Morar M, Anand R, Hoskins AA, Stubbe J, Ealick SE, Biochemistry. 2006 Dec 19;45(50):14880-95. PMID:17154526
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