Inhibitor binding within the NarI subunit (cytochrome bnr) of Escherichia coli nitrate reductase A.

The Journal of Biological Chemistry
Axel MagalonFrancis Blasco

Abstract

We have used inhibitors and site-directed mutants to investigate quinol binding to the cytochrome bnr (NarI) of Escherichia coli nitrate reductase (NarGHI). Both stigmatellin and 2-n-heptyl-4-hydroxyquinoline-N-oxide (HOQNO) inhibit menadiol:nitrate oxidoreductase activity with I50 values of 0.25 and 6 microM, respectively, and prevent the generation of a NarGHI-dependent proton electrochemical potential across the cytoplasmic membrane. These inhibitors have little effect on the rate of reduction of the two hemes of NarI (bL and bH), but have an inhibitory effect on the extent of nitrate-dependent heme reoxidation. No quinol-dependent heme bH reduction is detected in a mutant lacking heme bL (NarI-H66Y), whereas a slow but complete heme bL reduction is detected in a mutant lacking heme bH (NarI-H56R). This is consistent with physiological quinol binding and oxidation occurring at a site (QP) associated with heme bL which is located toward the periplasmic side of NarI. Optical and EPR spectroscopies performed in the presence of stigmatellin or HOQNO provide further evidence that these inhibitors bind at a heme bL-associated QP site. These results suggest a model for electron transfer through NarGHI that involves quinol binding a...Continue Reading

References

Dec 1, 1975·The Biochemical Journal·P B GarlandB A Haddock
Oct 21, 1976·Journal of Theoretical Biology·P Mitchell
Dec 7, 1989·Biochimica Et Biophysica Acta·M D Esposti
Jan 1, 1986·Methods in Enzymology·G von Jagow, T A Link
Apr 9, 1984·Biochimica Et Biophysica Acta·P R Rich
Jan 1, 1982·Molecular & General Genetics : MGG·M C PascalM Chippaux
Jun 13, 1997·Biochimica Et Biophysica Acta·C Hägerhäll

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Citations

Oct 22, 2008·Journal of Bacteriology·Masanori ToyofukuHiroo Uchiyama
Nov 28, 2015·Pathogens and Disease·Cristina Uribe-AlvarezSalvador Uribe-Carvajal
Oct 30, 2007·Biochimica Et Biophysica Acta·Richard A RotheryJoel H Weiner
Dec 17, 2010·Journal of Applied Microbiology·X ChenM Xu
Mar 21, 2017·International Journal of Genomics·Sintia AlmeidaVasco Azevedo
Dec 24, 2004·The Journal of Biological Chemistry·Michela G BerteroNatalie C J Strynadka
Apr 20, 2007·The Journal of Biological Chemistry·Pascal LancianoAxel Magalon
Nov 7, 2009·The Journal of Biological Chemistry·Stéphane GrimaldiBruno Guigliarelli
Apr 25, 2000·Biochimica Et Biophysica Acta·R Moreno-SánchezM E Torres-Márquez
Jun 25, 2014·Biochemistry·Justin G FedorJoel H Weiner

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