期刊
MICROBIOLOGY-SGM
卷 148, 期 -, 页码 3983-3992出版社
SOC GENERAL MICROBIOLOGY
DOI: 10.1099/00221287-148-12-3983
关键词
arsenic resistance; ArsR-like proteins; gene regulation
类别
The chromosomal arsenic-resistance (ars) operon of Acidithiobacillus ferrooxidans is atypical in that it is divergent, with its arsCR and arsBH genes transcribed in opposite directions. Furthermore, the amino-acid sequence of the putative ArsR-like regulator of the ars operon is not conserved in regions that have been shown to be responsible for binding to arsenic. Instead, the ArsR-like protein of At. ferrooxidans is related to a group of unstudied Ars-like proteins that have been found to be associated with chromosomal ars-like operons identified during genome-sequencing projects. Using arsB-lacZ, arsR-lacZ and arsC-lacZ fusions, it was shown that the ArsR-like protein of At. ferrooxidans is a repressor of the arsBH and arsRC genes of this organism, and that induction of gene expression took place when either AsIII (arsenite) or AsV (arsenate) were added. Deletion of 19 aa from the C terminus of the 118 aa ArsR protein did not affect the regulation of its activity, but deletion of an additional 28 aa inactivated ArsR. Northern-blot hybridization suggested that on induction of expression, the arsRC genes were transcribed in greater quantities than the arsBH genes, but that the level of induction was not affected by the form of arsenic added (AsIII or AsV).
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