Proton exit from the heme–copper oxidase of Escherichia coli
AUTOR(ES)
Puustinen, Anne
FONTE
The National Academy of Sciences
RESUMO
Pathways of proton entry have been identified in the proton-translocating heme–copper oxidases, but the proton exit pathway is unknown. Here we report experiments with cytochrome bo3 in Escherichia coli cells that may identify the beginning of the exit pathway. Systematic mutations of arginines 438 and 439 (R481 and R482 in the E. coli enzyme), numbering as in cytochrome aa3 from bovine heart mitochondria, which interact with the ring D propionates of the two heme groups, reveal that the D propionate of the oxygen-binding heme is involved in proton pumping; its anionic form must be stabilized in order for proton translocation to occur. This may locate the beginning of the pathway by which pumped protons exit from the enzyme structure.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=15088Documentos Relacionados
- The role of copper and protons in heme-copper oxidases: Kinetic study of an engineered heme-copper center in myoglobin
- The superfamily of heme-copper respiratory oxidases.
- The heme-copper oxidases of Thermus thermophilus catalyze the reduction of nitric oxide: Evolutionary implications
- Gene Cluster of Rhodothermus marinus High-Potential Iron-Sulfur Protein:Oxygen Oxidoreductase, a caa3-Type Oxidase Belonging to the Superfamily of Heme-Copper Oxidases
- Spectroscopic evidence for a heme-heme binuclear center in the cytochrome bd ubiquinol oxidase from Escherichia coli.