Transcriptional response of the obligate anaerobe Desulfuribacillus stibiiarsenatis MLFW‐2^T to growth on antimonate and other terminal electron acceptors

Abstract

Summary Enzymes of the dimethyl sulfoxide reductase (DMSOR) family catalyse two‐electron redox reactions pivotal to the dissimilatory metabolism of a variety of organic and inorganic compounds. The draft genome of the obligately anaerobic bacterium Desulfuribacillus stibiiarsenatis MLFW‐2T contains 14 genes that are predicted to encode catalytic subunits of DMSOR family enzymes. We quantified transcription of these genes during growth on antimonate, arsenate, nitrate and selenate, with the goal of identifying the respiratory antimonate reductase. Transcription of BHU72_10330, BHU72_03635 and BHU72_07355 was enhanced during growth on arsenate, nitrate and selenate, respectively, implicating these genes as encoding the catalytic subunits of a respiratory arsenate reductase (arrA), periplasmic nitrate reductase (napA) and membrane‐bound selenate reductase (srdA) respectively. Transcription of BHU72_07145 increased markedly when MLFW‐2T was grown on antimonate, suggesting that this gene encodes the catalytic subunit of a respiratory antimonate reductase, designated anrA. We also compared the transcriptomes of MLFW‐2T during growth on antimonate and arsenate to examine the broader physiological response of the organism to growth on these substrates. Relative to arsenate, antimonate was found to induce transcription of genes involved in pathways for dealing with oxidative stress, including those involved in repairing damaged cellular biomolecules and scavenging reactive oxygen species.

Identification of Antimonate Reducing Bacteria and Their Potential Metabolic Traits by the Combination of Stable Isotope Probing and Metagenomic-Pangenomic Analysis

“…Metagenomic-binning retrieved bins associated with Geobacter and Pseudomonas , providing an opportunity to investigate the functional genes responsible for Sb­(V) reduction. Genes encoding for respiratory Sb­(V) reductase ( anrA ) were reported as the key gene for Sb­(V) reduction in Desulfuribacillus stibiiarsenatis MLFW-2T . In this study, anrA was only detected in bins associated with Geobacter .…”

“…Given the chemical structural similarities between As and Sb, microorganisms may use similar metabolic pathways to transform both As and Sb. Indeed, the arrA gene encoding arsenate reductase could also contribute to the reduction of Sb­(V). , For example, Wang et al reported Sb­(V) reduction by Shewanella sp. ANA-3 through an arsenate respiratory reductase encoded by arrAB .…”

“…Genes responsible for Sb­(V) reduction were identified recently. For example, anrA encoding for a putative respiratory Sb­(V) reductase was recently identified from the obligate anaerobe Desulfuribacillus stibiiarsenatis MLFW-2T . In another study, Shi et al identified a putative Sb­(V) reductase designated as sbrA that was most closely related to periplasmic nitrate reductases and respiratory arsenate reductases, respectively …”

Sulfite oxidation by the quinone-reducing molybdenum sulfite dehydrogenase SoeABC from the bacterium Aquifex aeolicus

“…Proteins present in bands of gels were identified as previously described [19]. [31] have been determined close to the Molybdo-enzymes of the sulfur metabolism, we added these clades to our study. Aio sequences, used as outgroup, had been sampled before [30].…”

“…The thermodynamics of the considered reactions is not sufficient to explain the selectivity of which the function is still unknown and the Anr family, described by Abin and coworkers from which the antimonate reductase function has been established and which is very closely related to the Mo-bisPGD enzymes involved in sulfur metabolism [31]. For each of the sequence subfamilies, we have also taken special care to include sequences from the most diverse phylogenetic origins.…”