Involvement of multiple transcription factors for metal-induced spy gene expression in Escherichia coli.
Bacteria are directly exposed to metals in environment. To maintain the intracellular metal homeostasis, Escherichia coli contain a number of gene regulation systems, each for response to a specific metal. A periplasmic protein Spy of E. coli was found to be induced upon short-exposure to copper ion in CpxAR-dependent manner. Transcription of the spy gene was also induced by long-exposure to zinc ion. This induction, however, depended on another two-component system BaeSR. Using DNase-I footprinting assay, we identified two BaeR-binding regions on the spy promoter with a direct repeat of the BaeR-box sequence, TCTNCANAA. The zinc-responsive BaeR-binding sites were separated from copper-responsive CpxR-binding site, implying that the spy promoter responds to two species of metal independently through different using sensor-response regulator systems. Since BaeSR-dependent zinc response requires longer time, the induction of spy gene transcription by external zinc may include multiple steps such as through sensing the zinc-induced envelope disorder by BaeSR.
Yamamoto
Kaneyoshi
K
Department of Advanced Bioscience, Kinki University, Nakamachi, Nara, Japan.
Ogasawara
Hiroshi
H
Ishihama
Akira
A
D001426:Bacterial Proteins / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D018983:DNA Footprinting; D003850:Deoxyribonuclease I / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D053263:Gene Regulatory Networks; D005798:Genes, Bacterial; D008670:Metals / Q000494:pharmacology*; D008969:Molecular Sequence Data; D033903:Periplasmic Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism*
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008670:Metals; D033903:Periplasmic Proteins; C104888:Spy protein, E coli; D014157:Transcription Factors; D003850:Deoxyribonuclease I