Identification and Characterization of the Cyd Gene Locus of Escherichia Coli (Respiration, Membranes, Cloning, Energetics, Cytochromes)

The aerobic electron transport chain of Escherichia coli contains a terminal oxidase, cytochrome d, which is part of a two subunit protein complex that is composed of two additional cytochromes, b(,595) and b(,558). The first mutants affecting the cytochrome d complex (Cyd) have been isolated using two newly developed genetic procedures. These mutations are located in the gene locus, cyd, that mapped to minute 16.5 on the chromosome. The cyd gene and its promoter were cloned and shown to code for both subunits of Cyd. Strains bearing cloned cyd overproduce Cyd by 3- to 4-fold in stationary phase of growth resulting in yellow-green colored colonies of E. coli; purified Cyd is dark green. The color yields a convenient screening procedure for constructing deletions and insertions within cyd. This analysis has localized the region of cloned DNA that codes for subunit II. A spontaneous mutant of cloned cyd overproduces subunit I but does not make subunit II. This strain also overproduces cytochrome b(,558), but produces no cytochrome b(,595) or d. From this strain cytochrome b(,558) was purified in its native state. Purified cytochrome b(,558) is a ubiquinol oxidase, but it does not reduce molecular oxygen. The measured extinction coefficient of 21,000 M('-1) cm('-1) indicates a 1:1 stoichiometry of cytochrome b(,558) per Cyd.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Biochemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Green, George Neil

• Biology, Microbiology

Identifier

(UMI)AAI8521775

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/70542