Electron transfer from heme bL to the [3Fe-4S] cluster of Escherichia coli nitrate reductase A (NarGHI)

Biochemistry
Richard A RotheryJoel H Weiner

Abstract

We have investigated the functional relationship between three of the prosthetic groups of Escherichia coli nitrate reductase A (NarGHI): the two hemes of the membrane anchor subunit (NarI) and the [3Fe-4S] cluster of the electron-transfer subunit (NarH). In two site-directed mutants (NarGHI(H56R) and NarGHI(H205Y)) that lack the highest potential heme of NarI (heme b(H)), a large negative DeltaE(m,7) is elicited on the NarH [3Fe-4S] cluster, suggesting a close juxtaposition of these two centers in the holoenzyme. In a mutant retaining heme b(H), but lacking heme b(L) (NarGHI(H66Y)), there is no effect on the NarH [3Fe-4S] cluster redox properties. These results suggest a role for heme b(H) in electron transfer to the [3Fe-4S] cluster. Studies of the pH dependence of the [3Fe-4S] cluster, heme b(H), and heme b(L) E(m) values suggest that significant deprotonation is only observed during oxidation of the latter heme (a pH dependence of -36 mV pH(-1)). In NarI expressed in the absence of NarGH [NarI(DeltaGH)], apparent exposure of heme b(H) to the aqueous milieu results in both it and heme b(L) having E(m) values with pH dependencies of approximately -30 mV pH(-1). These results are consistent with heme b(H) being isolated from t...Continue Reading

References

Feb 1, 1995·European Journal of Biochemistry·W J IngledewJ C Salerno
Feb 1, 1994·Journal of Bioenergetics and Biomembranes·U ErmlerM Schiffer
Jun 6, 1998·The Journal of Biological Chemistry·A MagalonF Blasco
May 13, 1998·The Biochemical Journal·R A RotheryJ H Weiner
Aug 4, 1998·European Journal of Biochemistry·R A Rothery, J H Weiner
Nov 20, 1998·FEBS Letters·J P Allen, J C Williams

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Citations

Apr 27, 2010·Biochimica Et Biophysica Acta·Lai Lai YapRobert B Gennis
Oct 30, 2007·Biochimica Et Biophysica Acta·Richard A RotheryJoel H Weiner
Jun 25, 2014·Biochemistry·Justin G FedorJoel H Weiner
Apr 13, 2020·Journal of Biological Inorganic Chemistry : JBIC : a Publication of the Society of Biological Inorganic Chemistry·Breeanna MintmierPartha Basu
Dec 24, 2004·The Journal of Biological Chemistry·Michela G BerteroNatalie C J Strynadka
Jun 9, 2005·Journal of the American Chemical Society·Kyril M SolntsevDan Huppert

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