Essential role of cytochrome bd-related oxidase in cyanide resistance of Pseudomonas pseudoalcaligenes CECT5344.
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 and cioB, are clustered and encode the integral membrane proteins that correspond to subunits I and II of classical cytochrome bd, although the presence of heme d in the membrane could not be detected by difference spectra. The cio operon from P. pseudoalcaligenes presents a singular organization, starting upstream of cioAB 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 of cioA 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 cytochrome bd-related oxidase in the metabolism of cyanide by P. pseudoalcaligenes CECT5344.
Quesada
Alberto
A
Departamento de Bioquímica, Biología Molecular y Genética, Facultad de Veterinaria, Avda. de la Universidad s/n, 10071-Cáceres, España. aquesada@unex.es
Guijo
M Isabel
MI
Merchán
Faustino
F
Blázquez
Blas
B
Igeño
M Isabel
MI
Blasco
Rafael
R
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003486:Cyanides / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D023061:Gene Order; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009876:Operon; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D044205:Pseudomonas pseudoalcaligenes / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
D001426:Bacterial Proteins; D003486:Cyanides; D010088:Oxidoreductases