Transcriptome responses of Streptococcus mutans to peroxide stress: identification of novel antioxidant pathways regulated by Spx

The oxidative stress regulator Spx is ubiquitously found among Gram-positive bacteria. Previously, we reported identification of two Spx proteins in Streptococcus mutans - SpxA1 was the primary activator of oxidative stress genes whereas SpxA2 served a backup role. Here, we used RNA sequencing to un...

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Bibliographic Details
Published in:Scientific reports 2017-11, Vol.7 (1), p.16018-13, Article 16018
Main Authors: Kajfasz, Jessica K, Ganguly, Tridib, Hardin, Emily L, Abranches, Jacqueline, Lemos, José A
Format: Article
Language:English
Subjects:
Antioxidants
Antioxidants - metabolism
Bacterial Proteins - genetics
Gene expression
Gene Expression Regulation, Bacterial
Gram-positive bacteria
Hydrogen peroxide
Hydrogen Peroxide - pharmacology
Metabolic pathways
Oxidative stress
Oxidative Stress - drug effects
Ribonucleic acid
RNA
Streptococcus infections
Streptococcus mutans
Streptococcus mutans - drug effects
Streptococcus mutans - genetics
Streptococcus mutans - metabolism
Survival
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Summary:The oxidative stress regulator Spx is ubiquitously found among Gram-positive bacteria. Previously, we reported identification of two Spx proteins in Streptococcus mutans - SpxA1 was the primary activator of oxidative stress genes whereas SpxA2 served a backup role. Here, we used RNA sequencing to uncover the scope of the H O (peroxide)-stress regulon and to further explore the significance of Spx regulation in S. mutans. The transcriptome data confirmed the relationship between Spx and genes typically associated with oxidative stress, but also identified novel genes and metabolic pathways controlled by Spx during peroxide stress. While individual inactivation of newly identified peroxide stress genes had modest or no obvious consequences to bacterial survival, a phenotype enhancement screen using the ∆spxA1 strain as background for creation of double mutants revealed that four of the five genes inactivated were required for stress survival. Physiological and biochemical assays validated, at least in part, the transcriptome data indicating that SpxA1 coordinates transcriptional changes during peroxide stress that modify global metabolism and facilitate production of antioxidants. Collectively, our findings unraveled the scope of the peroxide stress regulon and expand the repertoire of oxidative stress genes in S. mutans, shedding new light on the role of Spx regulation.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-017-16367-5