Deletion of csn2 gene affects acid tolerance and exopolysaccharide synthesis in Streptococcus mutans. (25th August 2020)

• Record Type: Journal Article
• Authors: Zhang, Anqi; Chen, Jiamin; Gong, Tao; Lu, Miao; Tang, Boyu; Zhou, Xuedong; Li, Yuqing
• Is Part Of: Molecular oral microbiology. Volume 35:Number 5(2020)
• Page Start: 211
• Page End: 221
• Publication Date: 2020-08-25
• Subjects: acid tolerance -- CRISPR -- csn2 -- exopolysaccharide synthesis -- Streptococcus mutans; Mouth -- Microbiology -- Periodicals; Respiratory infections -- Microbiology -- Periodicals; Mouth -- Diseases -- Immunological aspects -- Periodicals; 617.522
• DOI: 10.1111/omi.12308
• Languages: English
• ISSNs: 2041-1006

Abstract

Abstract: Csn2 is an important protein of the CRISPR‐Cas system. The physiological function of this protein and its regulatory role in Streptococcus mutans, as the primary causative agent of human dental caries, is still unclear. In this study, we investigated whether csn2 deletion would affect S. mutans physiology and virulence gene expression. We used microscopic imaging, acid killing assays, pH drop, biofilm formation, and exopolysaccharide (EPS) production tests to determine whether csn2 deletion influenced S. mutans colony morphology, acid tolerance/production, and glucan formation abilities. Comparisons were made between quantitative Real‐Time Polymerase Chain Reaction (qRT‐PCR) data from the UA159 and csn2 deletion strain to determine the impact of csn2 knockout on S. mutans gene expression. The results showed that deletion of S. mutans csn2 changed its colony morphotype and made it more sensitive to acid. The expression levels of aciduricity genes, including leuA, leuB, leuC, and leuD, were significantly down‐regulated. Acid adaptation restored the aciduricity of csn2 mutant and enhanced the ability to synthesize EPS. The expression levels of EPS synthesis‐related genes, including gtfC and gtfD, were significantly up‐regulated after acid adaptation. In summary, deletion of S. mutans csn2 exerted multiple effects on the virulence traits of this pathogen, including acid tolerance and EPS formation, and that these alterations could partially be attributed to changes in gene expression upon loss of csn2 . Understanding the function of csn2 in S. mutans might lead to novel strategies to prevent or treat imbalances in oral microbiota that may favor diseases. Abstract : Deletion of csn2 gene, an important component of the CRISPR‐Cas9 system, affects colony morphology, acid tolerance and extracellular polysaccharide (EPS) synthesis in Streptococcus mutans. Genes involved in aciduricity and EPS‐synthesis are differentially expressed in the csn2 mutant. Understanding the function of csn2 in S. mutans might lead to novel strategies to prevent or treat imbalances in oral microbiota that may favor diseases.