Open AccessIsolation and characterization of a new class of cytochrome d terminal oxidase mutants of Escherichia coli
Author(s) -
Kristine L. Oden,
Robert B. Gennis
Publication year - 1991
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.173.19.6174-6183.1991
Subject(s) - biology , cytochrome , cytochrome c oxidase , mutant , mutagenesis , operon , plasmid , protein subunit , microbiology and biotechnology , heme , biochemistry , escherichia coli , electron transport complex iv , oxidase test , site directed mutagenesis , gene , enzyme
Cytochrome d terminal oxidase mutants were isolated by using hydroxylamine mutagenesis of pNG2, a pBR322-derived plasmid containing the wild-type cyd operon. The mutagenized plasmid was transformed into a cyo cyd recA strain, and the transformants were screened for the inability to confer aerobic growth on nonfermentable carbon sources. Western blot analysis and visible-light spectroscopy were performed to characterize three independent mutants grown both aerobically and anaerobically. The mutational variants of the cytochrome d complex were stabilized under anaerobic growth conditions. All three mutations perturb the b595 and d heme components of the complex. These mutations were mapped and sequenced and are shown to be located in the N-terminal third of subunit II of the cytochrome d complex. It is proposed that the N terminus of subunit II may interact with subunit I to form an interface that binds the b595 and d heme centers.