Gene expression of the arsenic resistance operon in Chromobacterium violaceum ATCC 12472.
Chromobacterium violaceum ATCC 12472 presents an arsRCB-type operon, which is involved in arsenic resistance. The regulating protein of this resistance system (ArsR) does not have the small conserved site (ELCVDCL) to link to the metalloid, as observed in Escherichia coli, and is thus considered to be an atypical ArsR protein, like that observed in Acidithiobacillus ferrooxidans. In the present study, the gene expression profile of the ars operon under induction at different concentrations of arsenite - As(III) - was obtained via real-time PCR (TaqMan), by correlating the threshold cycle (Ct) values of induced and uninduced (control) samples. Through linear regression analysis (R2 = 0.9926), the gene expression profile of the ars operon showed clearly that the 0.125 micromol/L concentration of As(III) was sufficient to provoke a 4-fold increase in the resistance system, and a further increase in concentration resulted in an increase of up to 53-fold in transcription rates. The relation between resistance and induction of the ars operon indicates that the increased resistance to As(III) is associated with the increase in the number of transcripts.
Azevedo
Juliana Simão Nina de
JS
Departamento de Genetica, Laboratorio de Polimorfismo de DNA, Universidade Federal do Para, Campus Universitario do Guama, Rua Augusto Correa 01, 66075-970 Belem - PA, Brazil.
Silva-Rocha
Rafael
R
Silva
Artur
A
Peixe Carepo
Marta Sofia
MS
Cruz Schneider
Maria Paula
MP
D042763:Acidithiobacillus / Q000235:genetics; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001151:Arsenic / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D002861:Chromobacterium / Q000737:chemistry / Q000235:genetics* / Q000254:growth & development; D017124:Conserved Sequence; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D009876:Operon; D012329:RNA, Bacterial / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D001151:Arsenic