Transcriptomic and genomic profiling revealed the unique cellular response mechanism involved in arsenite stress in Thermus tengchongensis

Abstract

Arsenic (As) is ubiquitous in geothermal fluids. Thermus plays an important role in As transformation in hot springs. However, few studies have focused on cellular response under arsenite (As[III]) stress and the regulation of As[III] oxidation in the genus Thermus. In this study, the global response to As[III] stress and regulation of As[III] oxidation in Thermus were explored with genomic and transcriptomic analyses. Global expression profiles of Thermus tengchongensis at intermediary phase of As[III] stress indicated that almost 50% (n = 1263) of the total genes (n = 2687) were involved in strain 15Y, versus only 7% (n = 191) of the total genes (n = 2656) in a natural mutant strain-15W. The number of differentially expressed genes (DEGs) is 286, 1263 and 86 at early, intermediary and late phase, respectively. The majority of genes encoding for As[III] oxidase, ArsR/SmtB family regulatory gene, As[III] efflux pump, TCA cycle, and catalase, etc. were up-regulated. And a substantial number of the genes encoding for Embden Meyerhof Parnas, metal ion channels andcarotenoid synthesis pathways were observed to be down-regulated. A novel member of ArsR/SmtB family, designed as AsoR, was explored with phylogenetic inference and structure identification among the Thermus species. This member has a common feature that there is a longer link between α2 and α3 compared with other metal sensor transcriptional repressors. A unique single-component system that universally existed in Thermus species was proposed. This study improves our understanding of microbial adaptation in the thermophilic As-rich environment.