Localization of acidic residues involved in the proton pumping activity of the bovine heart mitochondrial bc1 complex.
Chemical modification of carboxyl residues in polypeptide subunits of the mitochondrial bc1 complex causes a decoupling effect, that is inhibition of the proton pumping activity, without affecting the rate of electron transfer to ferricytochrome c. The study presented here is aimed at localizing and identifying the residues whose modification results in decoupling of the complex. Glutamate-53 in subunit IX (the DCCD-binding protein) and aspartate-166 in the Rieske iron-sulfur protein are the residues modified by N,N'-dicyclohexylcarbodiimide (DCCD) and N-(ethoxycarbonyl)-2-ethoxy-1,2-dihydroquinoline (EEDQ), respectively. The results obtained also suggest that the carboxy-terminal sequence of the Core protein II, which is fairly rich in acidic residues, may also play a role in the vectorial proton translocation activity of the complex.
Cocco
T
T
Institute of Medical Biochemistry and Chemistry, University of Bari, Italy.
Di Paola
M
M
Papa
S
S
Lorusso
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001224:Aspartic Acid / Q000737:chemistry; D002417:Cattle; D004024:Dicyclohexylcarbodiimide / Q000737:chemistry; D014450:Electron Transport Complex III / Q000737:chemistry* / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005452:Fluoresceins / Q000737:chemistry / Q000378:metabolism; D018698:Glutamic Acid / Q000737:chemistry; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000378:metabolism; D008929:Mitochondria, Heart / Q000201:enzymology*; D008969:Molecular Sequence Data; D011522:Protons; D011804:Quinolines / Q000737:chemistry; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid
C120907:4'-((aminoacetamido)methyl)fluorescein; D005452:Fluoresceins; D007506:Iron-Sulfur Proteins; D011522:Protons; D011804:Quinolines; D001224:Aspartic Acid; D018698:Glutamic Acid; D004024:Dicyclohexylcarbodiimide; C000470:EEDQ; D014450:Electron Transport Complex III