Dataset Information

The selectivity of Vibrio cholerae H-NOX for gaseous ligands follows the "sliding scale rule" hypothesis. Ligand interactions with both ferrous and ferric Vc H-NOX.

ABSTRACT: Vc H-NOX (or VCA0720) is an H-NOX (heme-nitric oxide and oxygen binding) protein from facultative aerobic bacterium Vibrio cholerae. It shares significant sequence homology with soluble guanylyl cyclase (sGC), a NO sensor protein commonly found in animals. Similar to sGC, Vc H-NOX binds strongly to NO and CO with affinities of 0.27 nM and 0.77 ?M, respectively, but weakly to O2. When positioned on a "sliding scale" plot [Tsai, A.-l., et al. (2012) Biochemistry 51, 172-186], the line connecting log K(D)(NO) and log K(D)(CO) of Vc H-NOX can almost be superimposed with that of Ns H-NOX. Therefore, the measured affinities and kinetic parameters of gaseous ligands to Vc H-NOX provide more evidence to validate the "sliding scale rule" hypothesis. Like sGC, Vc H-NOX binds NO in multiple steps, forming first a six-coordinate heme-NO complex at a rate of 1.1 × 10(9) M(-1) s(-1), and then converts to a five-coordinate heme-NO complex at a rate that is also dependent on NO concentration. Although the formation of oxyferrous Vc H-NOX cannot be detected at a normal atmospheric oxygen level, ferrous Vc H-NOX is oxidized to the ferric form at a rate of 0.06 s(-1) when mixed with O2. Ferric Vc H-NOX exists as a mixture of high- and low-spin states and is influenced by binding to different ligands. Characterization of both ferric and ferrous Vc H-NOX and their complexes with various ligands lays the foundation for understanding the possible dual roles in gas and redox sensing of Vc H-NOX.

SUBMITTER: Wu G

PROVIDER: S-EPMC3999706 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

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The selectivity of Vibrio cholerae H-NOX for gaseous ligands follows the "sliding scale rule" hypothesis. Ligand interactions with both ferrous and ferric Vc H-NOX.

Wu Gang G Liu Wen W Berka Vladimir V Tsai Ah-lim AL

Biochemistry 20131218 52

Vc H-NOX (or VCA0720) is an H-NOX (heme-nitric oxide and oxygen binding) protein from facultative aerobic bacterium Vibrio cholerae. It shares significant sequence homology with soluble guanylyl cyclase (sGC), a NO sensor protein commonly found in animals. Similar to sGC, Vc H-NOX binds strongly to NO and CO with affinities of 0.27 nM and 0.77 μM, respectively, but weakly to O2. When positioned on a "sliding scale" plot [Tsai, A.-l., et al. (2012) Biochemistry 51, 172-186], the line connecting l ...[more]

PMID: 24351060

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Dataset Information

The selectivity of Vibrio cholerae H-NOX for gaseous ligands follows the "sliding scale rule" hypothesis. Ligand interactions with both ferrous and ferric Vc H-NOX.

Publications

The selectivity of Vibrio cholerae H-NOX for gaseous ligands follows the "sliding scale rule" hypothesis. Ligand interactions with both ferrous and ferric Vc H-NOX.

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