Molecular characterization of the Escherichia coli htrD gene: cloning, sequence, regulation, and involvement with cytochrome d oxidase.
The Escherichia coli htrD gene was originally isolated during a search for new genes required for growth at high temperature. Insertional inactivation of htrD leads to a pleiotropic phenotype characterized by temperature-sensitive growth in rich medium, H2O2 sensitivity, and sensitivity to cysteine. The htrD gene was cloned and sequenced, and an htrD::mini-Tn10 insertion mutation was mapped within this gene. The htrD gene was shown to encode a protein of approximately 17.5 kDa. Expression of the htrD gene was examined by using an phi (htrD-lacZ) operon fusion. It was found that htrD is not temperature regulated and therefore is not a heat shock gene. Further study revealed that htrD expression is increased under aerobic growth conditions. Conversely, under anaerobic growth conditions, htrD expression is decreased. In addition, a mutation within the nearby cydD gene was found to drastically reduce htrD expression under all conditions tested. These results indicate that htrD is somehow involved in aerobic respiration and that the cydD gene product is necessary for htrD gene expression. In agreement with this conclusion, htrD mutant bacteria are unable to oxidize the cytochrome d-specific electron donor N,N,N',N'-tetramethyl-p-phenylenediamine.
Department of Cellular, Viral, and Molecular Biology, University of Utah School of Medicine, Salt Lake City 84132.
J M
JM
Delaney
D
D
Wall
C
C
Georgopoulos
D018528:ATP-Binding Cassette Transporters; D000332:Aerobiosis; D000595:Amino Acid Sequence; D000693:Anaerobiosis; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D003545:Cysteine / Q000494:pharmacology; D003573:Cytochrome b Group; D017937:Cytochrome d Group; D003580:Cytochromes / Q000378:metabolism*; D045222:Electron Transport Chain Complex Proteins; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics*; D005816:Genetic Complementation Test; D006358:Hot Temperature; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000378:metabolism*; D010101:Oxygen Consumption / Q000235:genetics; D010641:Phenotype; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D015183:Restriction Mapping; D013489:Suppression, Genetic; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; C089839:CydD protein, E coli; D003573:Cytochrome b Group; D003580:Cytochromes; D045222:Electron Transport Chain Complex Proteins; D029968:Escherichia coli Proteins; D011993:Recombinant Fusion Proteins; D017937:Cytochrome d Group; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; C040077:cytochrome bd terminal oxidase complex, E coli; D001616:beta-Galactosidase; D003545:Cysteine