Open AccessEssential Role of Cytochromebd-Related Oxidase in Cyanide Resistance ofPseudomonas pseudoalcaligenesCECT5344
Author(s) -
Alberto Quesada,
Ma Isabel Guijo,
Faustino Merchán,
Blas Blázquez,
M. Isabel Igeño,
Rafael Blasco
Publication year - 2007
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.00503-07
Subject(s) - cyanide , operon , biology , cytochrome c oxidase , biochemistry , cytochrome , microbiology and biotechnology , gene , chemistry , enzyme , inorganic chemistry , escherichia coli
Pseudomonas pseudoalcaligenes CECT5344 grows in minimal medium containing cyanide as the sole nitrogen source. Under these conditions, an O2 -dependent respiration highly resistant to cyanide was detected in cell extracts. The structural genes for the cyanide-resistant terminal oxidase,cioA andcioB , are clustered and encode the integral membrane proteins that correspond to subunits I and II of classical cytochromebd , although the presence of hemed in the membrane could not be detected by difference spectra. Thecio operon fromP. pseudoalcaligenes presents a singular organization, starting upstream ofcioAB by the coding sequence of a putative ferredoxin-dependent sulfite or nitrite reductase and spanning downstream two additional open reading frames that encode uncharacterized gene products. PCR amplifications of RNA (reverse transcription-PCR) indicated the cyanide-dependent up-regulation and cotranscription along the operon. The targeted disruption ofcioA eliminates both the expression of the cyanide-stimulated respiratory activity and the growth with cyanide as the nitrogen source, which suggests a critical role of this cytochromebd -related oxidase in the metabolism of cyanide byP. pseudoalcaligenes CECT5344.