Transcription factor YcjW controls the emergency H2S production in E. coli

Abstract

Prokaryotes and eukaryotes alike endogenously generate the gaseous molecule hydrogen sulfide (H 2 S). Bacterial H 2 S acts as a cytoprotectant against antibiotics-induced stress and promotes redox homeostasis. In E. coli , endogenous H 2 S production is primarily dependent on 3-mercaptopyruvate sulfurtransferase (3MST), encoded by mstA . Here, we show that cells lacking 3MST acquire a phenotypic suppressor mutation resulting in compensatory H 2 S production and tolerance to antibiotics and oxidative stress. Using whole genome sequencing, we identified a non-synonymous mutation within an uncharacterized LacI-type transcription factor, ycjW . We then mapped regulatory targets of YcjW and discovered it controls the expression of carbohydrate metabolic genes and thiosulfate sulfurtransferase PspE. Induction of pspE expression in the suppressor strain provides an alternative mechanism for H 2 S biosynthesis. Our results reveal a complex interaction between carbohydrate metabolism and H 2 S production in bacteria and the role, a hitherto uncharacterized transcription factor, YcjW, plays in linking the two.

Structural determinants of persulfide-sensing specificity in a dithiol-based transcriptional regulator

“…Regulatory posttranslational modifications on thiol groups of redox-active and allosterically important cysteines are a critical component of signaling and redox regulation in cells 1–3 . The successful adaptation of microorganisms to an ever-changing microenvironment depends, to a considerable degree, on the specificity of the regulation of the expression of needed repair enzymes 4–6 . Understanding the extent to which transcriptional regulation is specific to a particular redox-active small molecule(s) is complicated by cross-talk or interconversion among these species in cells 7,8 and the difficulties associated with identifying a posttranslational modification that is biologically meaningful at cell-appropriate concentrations that induce a cellular response 9 .…”

“…Recent work suggests that the upregulation of host-derived or bacterially-produced hydrogen sulfide (H 2 S) and downstream reactive sulfur species (RSS) is protective against a myriad of oxidative and nitrosative stressors in cells or animals infected by a number of medically important bacterial pathogens 4,16–20 . However, the cellular concentrations of H 2 S and more reactive RSS must be controlled to leverage these beneficial effects of H 2 S, while avoiding cellular toxicity 21 .…”

“…In conclusion, we demonstrate that it is indeed possible for non-metallated, dithiol-based transcriptional regulators to achieve a level of specificity required for bacterial cells to trigger a unique response to RSS/H 2 S toxicity rather than general redox misbalance. This is functionally important since increased H 2 S biogenesis has been shown to be necessary for bacteria to counteract the effect of antibiotic stress and host derived reactive oxygen and nitrogen species stressors 4,16,19,42 . We show that this chemical specificity derives from a unique energetic landscape dictated by the protein matrix, which dictates the spectrum of posttranslational modifications by minimizing local structural frustration, while exploiting steric hindrance and low nucleophilicity.…”

H2S and reactive sulfur signaling at the host-bacterial pathogen interface

“…In the infected host, H 2 S and RSS are derived from host cell metabolism, from commensal bacteria in polymicrobial communities, or from the pathogen itself. Recent studies that build on prior work (21) suggest that bacterial H 2 S biogenesis may well be a clinically important adaptive response during infections (22)(23)(24)(25)(26).…”

Genome re-sequencing and reannotation of the Escherichia coli ER2566 strain and transcriptome sequencing under overexpression conditions

“…Next-generation sequencing (NGS) is a cost-effective tool for the study of gene function and experimental bacterial evolution. Indeed, NGS technology was used by Luhachack and colleagues to successfully identify the function of the transcription factor YcjW as a regulator of the complex interaction between carbohydrate metabolism and H2S production in bacteria [12], and whole-genome re-sequencing in E. coli by Herring et al led to the identi cation of mutations that conveyed a selective growth advantage during adaptation to a glycerol-based growth medium [13]. Even though the ER2566 engineering strain is widely used for the preparation of virus-like particles [14], and bacterial surface display [15], among other functions, exploring bacterial adaptive evolution of the ER2566 strain under various external pressures through NGS remains di cult and inconclusive because of limitations in the annotations of the strain [13].…”