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spinqualitylabelsall models 1tll, resolution 2.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

CRYSTAL STRUCTURE OF RAT NEURONAL NITRIC-OXIDE SYNTHASE REDUCTASE MODULE AT 2.3 A RESOLUTION.

Overview

Three nitric-oxide synthase (NOS) isozymes play crucial, but distinct, roles in neurotransmission, vascular homeostasis, and host defense, by catalyzing Ca(2+)/calmodulin-triggered NO synthesis. Here, we address current questions regarding NOS activity and regulation by combining mutagenesis and biochemistry with crystal structure determination of a fully assembled, electron-supplying, neuronal NOS reductase dimer. By integrating these results, we structurally elucidate the unique mechanisms for isozyme-specific regulation of electron transfer in NOS. Our discovery of the autoinhibitory helix, its placement between domains, and striking similarities with canonical calmodulin-binding motifs, support new mechanisms for NOS inhibition. NADPH, isozyme-specific residue Arg(1400), and the C-terminal tail synergistically repress NOS activity by locking the FMN binding domain in an electron-accepting position. Our analyses suggest that calmodulin binding or C-terminal tail phosphorylation frees a large scale swinging motion of the entire FMN domain to deliver electrons to the catalytic module in the holoenzyme.

About this Structure

1TLL is a Single protein structure of sequence from Rattus norvegicus with , , and as ligands. Active as Nitric-oxide synthase, with EC number 1.14.13.39 Full crystallographic information is available from OCA.

Reference

Structural basis for isozyme-specific regulation of electron transfer in nitric-oxide synthase., Garcin ED, Bruns CM, Lloyd SJ, Hosfield DJ, Tiso M, Gachhui R, Stuehr DJ, Tainer JA, Getzoff ED, J Biol Chem. 2004 Sep 3;279(36):37918-27. Epub 2004 Jun 17. PMID:15208315

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