Insight into the active-site structure and function of cytochrome oxidase by analysis of site-directed mutants of bacterial cytochrome aa3 and cytochrome bo.
Cytochrome aa3 of Rhodobacter sphaeroides and cytochrome bo of E. coli are useful models of the more complex cytochrome c oxidase of eukaryotes, as demonstrated by the genetic, spectroscopic, and functional studies reviewed here. A summary of site-directed mutants of conserved residues in these two enzymes is presented and discussed in terms of a current model of the structure of the metal centers and evidence for regions of the protein likely to be involved in proton transfer. The model of ligation of the heme a3 (or o)-CuB center, in which both hemes are bound to helix X of subunit I, has important implications for the pathways and control of electron transfer.
Department of Biochemistry, Michigan State University, East Lansing 48824.
J P
JP
Hosler
S
S
Ferguson-Miller
M W
MW
Calhoun
J W
JW
Thomas
J
J
Hill
L
L
Lemieux
J
J
Ma
C
C
Georgiou
J
J
Fetter
J
J
Shapleigh
D000595:Amino Acid Sequence; D001665:Binding Sites; D003573:Cytochrome b Group; D003580:Cytochromes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins; D008961:Models, Structural; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012242:Rhodobacter sphaeroides / Q000201:enzymology*
D003573:Cytochrome b Group; D003580:Cytochromes; D029968:Escherichia coli Proteins; D011994:Recombinant Proteins; C017168:cytochrome bo, E coli; D003576:Electron Transport Complex IV