1gso

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spinqualitylabelsall models 1gso, resolution 1.6Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

GLYCINAMIDE RIBONUCLEOTIDE SYNTHETASE (GAR-SYN) FROM E. COLI.

Overview

Glycinamide ribonucleotide synthetase (GAR-syn) catalyzes the second step, of the de novo purine biosynthetic pathway; the conversion of, phosphoribosylamine, glycine, and ATP to glycinamide ribonucleotide (GAR), ADP, and Pi. GAR-syn containing an N-terminal polyhistidine tag was, expressed as the SeMet incorporated protein for crystallographic studies., In addition, the protein as isolated contains a Pro294Leu mutation. This, protein was crystallized, and the structure solved using, multiple-wavelength anomalous diffraction (MAD) phase determination and, refined to 1.6 A resolution. GAR-syn adopts an alpha/beta structure that, consists of four domains labeled N, A, B, and C. The N, A, and C domains, are clustered to form a large central core structure whereas the smaller B, domain is extended outward. Two hinge regions, which might readily, facilitate interdomain movement, connect the B domain and the main core. A, search of structural databases showed that the structure of GAR-syn is, similar to D-alanine:D-alanine ligase, biotin carboxylase, and glutathione, synthetase, despite low sequence similarity. These four enzymes all, utilize similar ATP-dependent catalytic mechanisms even though they, catalyze different chemical reactions. Another ATP-binding enzyme with low, sequence similarity but unknown function, synapsin Ia, was also found to, share high structural similarity with GAR-syn. Interestingly, the GAR-syn, N domain shows similarity to the N-terminal region of glycinamide, ribonucleotide transformylase and several dinucleotide-dependent, dehydrogenases. Models of ADP and GAR binding were generated based on, structure and sequence homology. On the basis of these models, the active, site lies in a cleft between the large domain and the extended B domain., Most of the residues that facilitate ATP binding belong to the A or B, domains. The N and C domains appear to be largely responsible for, substrate specificity. The structure of GAR-syn allows modeling studies of, possible channeling complexes with PPRP amidotransferase.

About this Structure

1GSO is a Single protein structure of sequence from Escherichia coli. Active as Phosphoribosylamine--glycine ligase, with EC number 6.3.4.13 Full crystallographic information is available from OCA.

Reference

X-ray crystal structure of glycinamide ribonucleotide synthetase from Escherichia coli., Wang W, Kappock TJ, Stubbe J, Ealick SE, Biochemistry. 1998 Nov 10;37(45):15647-62. PMID:9843369

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