Identification of the cydC locus required for expression of the functional form of the cytochrome d terminal oxidase complex in Escherichia coli.

AUTOR(ES)

Georgiou, C D

RESUMO

The aerobic respiratory chain of Escherichia coli contains two terminal oxidases which are differentially regulated. The cytochrome o complex predominates under growth conditions of high aeration, whereas the cytochrome d complex predominates when the oxygen tension is low. Either terminal oxidase will support aerobic growth. The goal of the work presented in this paper was to identify genes required for the expression of the functional form of the cytochrome d complex, other than the genes encoding the polypeptide components of the oxidase complex (cyd locus). A strain lacking the cytochrome o complex (cyo mutant strain) was mutagenized by using a lambda-Mu hybrid hopper bacteriophage, lambda placMu53, which inserts randomly into the chromosome and carries a kanamycin resistance marker. Strains were isolated and examined which were unable to grow aerobically, i.e., which lacked functional cytochrome d complex, and which could not be complemented by introduction of the cyd gene on F-prime episomes. One strain was selected for characterization. The phage insert was mapped to min 18.9 on the genetic linkage map, defining a new genetic locus, cydC. Evidence described in the text suggests that the gene product is probably required for the synthesis of the unique heme d component of the cytochrome d complex.

Documentos Relacionados

• The stationary-phase-exit defect of cydC (surB) mutants is due to the lack of a functional terminal cytochrome oxidase.
• Physical map locations of the trxB, htrD, cydC, and cydD genes of Escherichia coli.
• Cloning of the cyo locus encoding the cytochrome o terminal oxidase complex of Escherichia coli.
• Regulation of expression of the cytochrome d terminal oxidase in Escherichia coli is transcriptional.
• Isolation and characterization of a new class of cytochrome d terminal oxidase mutants of Escherichia coli.