The product of the ybdE gene of the Escherichia coli chromosome is involved in detoxification of silver ions.
Transcription of the ybcZ--ylcA ylcBCD--ybdE region of the Escherichia coli K38 chromosome was analysed by Northern RNA--DNA hybridization, RT-PCR and primer extension. Transcription of a dicistronic ybcZ--ylcA mRNA and a tetracistronic ylcBCD--ybdE mRNA was induced by silver and was initiated from the sigma-70 promoters ylcAp and ylcBp. Expression of beta-galactosidase activity from a Phi(ylcBp--lacZ) operon fusion was also induced by Ag(+) and Cu(2+), but not by Zn(2+). In-frame deletion of ybdE from the chromosome yielded a silver-sensitive E. coli mutant strain which did not differ in its copper resistance from its wild-type strain. On the other hand, deletion of the copA gene for the copper-exporting P-type ATPase CopA resulted in copper sensitivity, but not in silver sensitivity. A Delta ybdE Delta copA double mutant strain behaved towards copper as the Delta copA strain and towards silver as the Delta ybdE strain. Thus, in E. coli, the YlcBCD--YbdE system may be involved in silver- but not in copper resistance, and CopA may be involved in copper- but not in silver resistance.
Institut für Mikrobiologie der Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Str. 3, 06099 Halle, Germany1.
Sylvia
S
Franke
Institut für Mikrobiologie der Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Str. 3, 06099 Halle, Germany1.
Gregor
G
Grass
Institut für Mikrobiologie der Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Str. 3, 06099 Halle, Germany1.
Dietrich H
DH
Nies
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015152:Blotting, Northern; D002876:Chromosomes, Bacterial; D003300:Copper / Q000378:metabolism / Q000633:toxicity; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D005798:Genes, Bacterial; D017930:Genes, Reporter; D007763:Lac Operon; D009876:Operon; D011401:Promoter Regions, Genetic; D012329:RNA, Bacterial / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017384:Sequence Deletion; D012834:Silver / Q000378:metabolism* / Q000633:toxicity
D001426:Bacterial Proteins; C071263:CopA protein, Bacteria; D012329:RNA, Bacterial; D012834:Silver; D003300:Copper