TY - JOUR
T1 - The cytochrome bd respiratory oxygen reductases
AU - Borisov, Vitaliy B.
AU - Gennis, Robert B.
AU - Hemp, James
AU - Verkhovsky, Michael I.
N1 - Funding Information:
Studies in our groups were supported by the Russian Foundation for Basic Research , grant 11-04-00031-a (to V.B.B.), the National Institutes of Health , grant HL16101 (to R.B.G.), and the Biocentrum Helsinki , the Sigrid Jusélius Foundation , and the Academy of Finland (to M.I.V.).
PY - 2011/11
Y1 - 2011/11
N2 - Cytochrome bd is a respiratory quinol:O2 oxidoreductase found in many prokaryotes, including a number of pathogens. The main bioenergetic function of the enzyme is the production of a proton motive force by the vectorial charge transfer of protons. The sequences of cytochromes bd are not homologous to those of the other respiratory oxygen reductases, i.e., the heme-copper oxygen reductases or alternative oxidases (AOX). Generally, cytochromes bd are noteworthy for their high affinity for O2 and resistance to inhibition by cyanide. In E. coli, for example, cytochrome bd (specifically, cytochrome bd-I) is expressed under O2-limited conditions. Among the members of the bd-family are the so-called cyanide-insensitive quinol oxidases (CIO) which often have a low content of the eponymous heme d but, instead, have heme b in place of heme d in at least a majority of the enzyme population. However, at this point, no sequence motif has been identified to distinguish cytochrome bd (with a stoichiometric complement of heme d) from an enzyme designated as CIO. Members of the bd-family can be subdivided into those which contain either a long or a short hydrophilic connection between transmembrane helices 6 and 7 in subunit I, designated as the Q-loop. However, it is not clear whether there is a functional consequence of this difference. This review summarizes current knowledge on the physiological functions, genetics, structural and catalytic properties of cytochromes bd. Included in this review are descriptions of the intermediates of the catalytic cycle, the proposed site for the reduction of O2, evidence for a proton channel connecting this active site to the bacterial cytoplasm, and the molecular mechanism by which a membrane potential is generated.
AB - Cytochrome bd is a respiratory quinol:O2 oxidoreductase found in many prokaryotes, including a number of pathogens. The main bioenergetic function of the enzyme is the production of a proton motive force by the vectorial charge transfer of protons. The sequences of cytochromes bd are not homologous to those of the other respiratory oxygen reductases, i.e., the heme-copper oxygen reductases or alternative oxidases (AOX). Generally, cytochromes bd are noteworthy for their high affinity for O2 and resistance to inhibition by cyanide. In E. coli, for example, cytochrome bd (specifically, cytochrome bd-I) is expressed under O2-limited conditions. Among the members of the bd-family are the so-called cyanide-insensitive quinol oxidases (CIO) which often have a low content of the eponymous heme d but, instead, have heme b in place of heme d in at least a majority of the enzyme population. However, at this point, no sequence motif has been identified to distinguish cytochrome bd (with a stoichiometric complement of heme d) from an enzyme designated as CIO. Members of the bd-family can be subdivided into those which contain either a long or a short hydrophilic connection between transmembrane helices 6 and 7 in subunit I, designated as the Q-loop. However, it is not clear whether there is a functional consequence of this difference. This review summarizes current knowledge on the physiological functions, genetics, structural and catalytic properties of cytochromes bd. Included in this review are descriptions of the intermediates of the catalytic cycle, the proposed site for the reduction of O2, evidence for a proton channel connecting this active site to the bacterial cytoplasm, and the molecular mechanism by which a membrane potential is generated.
KW - Bacterial physiology
KW - Disease
KW - Metabolism
KW - Microbe
KW - Molecular bioenergetics
KW - Oxidoreduction
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U2 - 10.1016/j.bbabio.2011.06.016
DO - 10.1016/j.bbabio.2011.06.016
M3 - Review article
C2 - 21756872
AN - SCOPUS:80052756459
SN - 0005-2728
VL - 1807
SP - 1398
EP - 1413
JO - Biochimica et Biophysica Acta - Bioenergetics
JF - Biochimica et Biophysica Acta - Bioenergetics
IS - 11
ER -