Listeria monocytogenes SpxA1 is a global regulator required to activate genes encoding catalase and heme biosynthesis enzymes for aerobic growth

Abstract

An imbalance of cellular oxidants and reductants causes redox stress, which must be rapidly detected to restore homeostasis. In bacteria, the Firmicutes encode conserved Spx‐family transcriptional regulators that modulate transcription in response to redox stress. SpxA1 is an Spx‐family orthologue in the intracellular pathogen Listeria monocytogenes that is essential for aerobic growth and pathogenesis. Here, we investigated the role of SpxA1 in growth and virulence by identifying genes regulated by SpxA1 in broth and during macrophage infection. We found SpxA1‐activated genes encoding heme biosynthesis enzymes and catalase ( kat ) were required for L. monocytogenes aerobic growth in rich medium. An Spx‐recognition motif previously defined in Bacillus subtilis was identified in the promoters of SpxA1‐activated genes and proved necessary for the proper activation of two genes, indicating this regulation by SpxA1 is likely direct. Together, these findings elucidated the mechanism of spxA1 essentiality in vitro and demonstrated that SpxA1 is required for basal expression of scavenging enzymes to combat redox stress generated in the presence of oxygen.

Integrated Transcriptomic and Proteomic Analyses Reveal the Role of NprR in Bacillus anthracis Extracellular Protease Expression Regulation and Oxidative Stress Responses

“…These results may explain why the mutant strain is more sensitive to hydrogen peroxide. Previous work showed that the analogous genes were also downregulated in spxA1 deletion mutant and these mutant strains were more sensitive to hydrogen peroxide in Streptococcus sanguinis and Listeria monocytogenes than wild-type strains (Chen et al, 2012;Cesinger et al, 2020). The mechanism by which BprR protein regulates these genes remains unclear, and further work is still needed to provide an adequate explanation.…”

“…Both SpxA1 and SpxA2 are closely related to the oxidative stress responses of B. anthracis , and spxA1 is essential for peroxide resistance and participates in disulfide stress tolerance ( Barendt et al, 2013 , 2016 ). SpxA1 is also involved in oxidative stress response of many gram-positive bacteria ( Chen et al, 2012 ; Kajfasz et al, 2017 ; Nilsson et al, 2019 ; Cesinger et al, 2020 ). For example, Chen et al (2012) reported that SpxA1 is a global regulator required to activate genes encoding catalase in Listeria monocytogenes , and Nilsson et al (2019) also reported that SpxA1 is involved in the oxidative stress response in Streptococcus mutans .…”

The global redox-responsive transcriptional regulator Rex represses fermentative metabolism and is required forListeria monocytogenespathogenesis

“…Briefly, bacteria were grown overnight in BHI shaking at °C and subcultured to an optical density at nm (OD 600 ) of 0.02 into 25 mL BHI. [51]. Results were evaluated using CLC Genomics Workbench (Qiagen) and transcripts that were changed >2-fold (p < .01) were included in our analysis.…”

“…In Intracellular growth curves. Growth curves in bone marrow-derived macrophages (BMMs) were performed as previously described [51], with the following modifications.…”

Table_2.XLSX

“…Both SpxA1 and SpxA2 are closely related to the oxidative stress responses of B. anthracis, and spxA1 is essential for peroxide resistance and participates in disulfide stress tolerance (Barendt et al, 2013(Barendt et al, , 2016. SpxA1 is also involved in oxidative stress response of many grampositive bacteria (Chen et al, 2012;Kajfasz et al, 2017;Nilsson et al, 2019;Cesinger et al, 2020). For example, Chen et al (2012) reported that SpxA1 is a global regulator required to activate genes encoding catalase in Listeria monocytogenes, and Nilsson et al (2019) also reported that SpxA1 is involved in the oxidative stress response in Streptococcus mutans.…”