Differential gene expression in response to copper inAcidithiobacillus ferrooxidans analyzed by RNA arbitrarily primed polymerase chain reaction

Abstract

Acidithiobacillus ferrooxidans is a chemoautotrophic bacterium that plays an important role in metal bioleaching processes. Despite the high level of tolerance to heavy metals shown by A. ferrooxidans, the genetic basis of copper resistance in this species remains unknown. We investigated the gene expression in response to copper in A. ferrooxidans LR using RNA arbitrarily primed polymerase chain reaction (RAP-PCR). One hundred and four differentially expressed genes were identified using eight arbitrary primers. Differential gene expression was confirmed by DNA slot blot hybridization, and approximately 70% of the RAP-PCR products were positive. The RAP-PCR products that presented the highest levels of induction or repression were cloned, sequenced and the sequences were compared with those in databases using the BLAST search algorithm. Seventeen sequences were obtained. The RAP-PCR product with the highest induction ratio showed similarity with the A. ferrooxidans cytochrome c. A high similarity with the thiamin biosynthesis gene thiC from Caulobacter crescentus was observed for another RAP-PCR product induced by copper. An RAP-PCR product repressed by copper showed significant similarity with the carboxysome operon that includes the ribulose-1,5-bisphosphate carboxylase/oxygenase complex from A. ferrooxidans and another copper-repressed product was significantly similar to the XyIN outer membrane protein from Pseudomonas putida. Finally, RAP-PCR products of unknown similarities were also present.

Growth in sulfidic mineral environments: metal resistance mechanisms in acidophilic micro-organisms

“…Also, RNA arbitrarily primed PCR identified 17 genes induced by Cu(II) in At. ferrooxidans (Paulino et al, 2002). However, on those occasions no genes with homologies to Cu(II) resistance genes were identified.…”

Transcriptional and Functional Studies of Acidithiobacillus ferrooxidans Genes Related to Survival in the Presence of Copper

“…Nevertheless, the role of these genes in the mechanism of Cu resistance is still unclear, and their expression may be related to indirect metabolic responses to stress (20). Novo et al (18) also studied changes in some proteins from A. ferrooxidans when subjected to Cu and other metals, but the proteins were not identified.…”

Differential gene expression in response to copper in Acidithiobacillus ferrooxidans strains possessing dissimilar copper resistance

“…Though some studies have focused on copper resistance (Paulino et al, 2002), few genes have been identified that are directly involved in the copper tolerance of At.ferrooxidans. In 2007, the At.ferrooxidans ATCC23270 genome was sequenced by The Institute for Genomic Research (TIGR), and afe_0454 was annotated as being related to copper-resistance.…”