1m7v

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Revision as of 19:05, 20 November 2007

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spinqualitylabelsall models 1m7v, resolution 1.95Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

STRUCTURE OF A NITRIC OXIDE SYNTHASE HEME PROTEIN FROM BACILLUS SUBTILIS WITH TETRAHYDROFOLATE AND ARGININE BOUND

Overview

Eukaryotic nitric oxide synthases (NOSs) produce nitric oxide to mediate, intercellular signaling and protect against pathogens. Recently, proteins, homologous to mammalian NOS oxygenase domains have been found in, prokaryotes and one from Bacillus subtilis (bsNOS) has been demonstrated, to produce nitric oxide [Adak, S., Aulak, K. S., and Stuehr, D. J. (2002), J. Biol. Chem. 277, 16167-16171]. We present structures of bsNOS complexed, with the active cofactor tetrahydrofolate and the substrate L-arginine, (L-Arg) or the intermediate N(omega)-hydroxy-L-arginine (NHA) to 1.9 or, 2.2 A resolution, respectively. The bsNOS structure is similar to those of, the mammalian NOS oxygenase domains (mNOS(ox)) except for the absence of, an N-terminal beta-hairpin hook and zinc-binding region that interact with, pterin and stabilize the mNOS(ox) dimer. Changes in patterns of residue, conservation between bacterial and mammalian NOSs correlate to different, binding modes for pterin side chains. Residue conservation on a surface, patch surrounding an exposed heme edge indicates a likely interaction site, for reductase proteins in all NOSs. The heme pockets of bsNOS and mNOS(ox), recognize L-Arg and NHA similarly, although a change from Val to Ile, beside the substrate guanidinium may explain the 10-20-fold slower, dissociation of product NO from the bacterial enzyme. Overall, these, structures suggest that bsNOS functions naturally to produce nitrogen, oxides from L-Arg and NHA in a pterin-dependent manner, but that the, regulation and purpose of NO production by NOS may be quite different in, B. subtilis than in mammals.

About this Structure

1M7V is a Single protein structure of sequence from Bacillus subtilis with ARG, HEM and THG as ligands. Active as Nitric-oxide synthase, with EC number 1.14.13.39 Full crystallographic information is available from OCA.

Reference

Structure of a nitric oxide synthase heme protein from Bacillus subtilis., Pant K, Bilwes AM, Adak S, Stuehr DJ, Crane BR, Biochemistry. 2002 Sep 17;41(37):11071-9. PMID:12220171

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