Effects of multicopy LeuO on the expression of the acid-inducible lysine decarboxylase gene in Escherichia coli.
We previously reported that mutations in hns, the structural gene for the histone-like protein H-NS, cause derepressed expression of cadA, which encodes the acid-inducible lysine decarboxylase at noninducing pH (pH 8.0). This study reports the characterization of a plasmid isolated from an Escherichia coli library that suppresses the effect of an hns mutation on cadA expression. A previously sequenced open reading frame, leuO, proves to be the gene that causes the hns-complementing phenotype. The mechanism for this phenotype appears to be overexpression of leuO from a multicopy plasmid, which drastically reduces production of CadC, the essential activator for cadA induction. These results show an in vivo regulatory phenotype for leuO, consistent with its proposed protein sequence.
Shi
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Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77251.
Bennett
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D001426:Bacterial Proteins; D002262:Carboxy-Lyases / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D009687:Nuclear Proteins / Q000235:genetics; D016366:Open Reading Frames; D010957:Plasmids; D012333:RNA, Messenger / Q000032:analysis; D001616:beta-Galactosidase / Q000096:biosynthesis
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C031908:H-NS protein, bacteria; D009687:Nuclear Proteins; D012333:RNA, Messenger; D001616:beta-Galactosidase; D002262:Carboxy-Lyases; C021520:lysine decarboxylase