The Major Autolysin of Streptococcus gordonii Is Subject to Complex Regulation and Modulates Stress Tolerance, Biofilm Formation, and Extracellular-DNA Release

摘要: A gene, designated atlS, encoding a major autolysin from Streptococcus gordonii, was identified and characterized. The predicted AtlS protein is 1,160 amino acids 127 kDa has conserved β1,4-N-acetylmuramidase domain. Zymographic analysis of wild-type S. gordonii revealed peptidoglycan hydrolase activities with molecular masses 130 90 that were absent in an atlS deletion mutant. Western blotting the 90-kDa band derived 130-kDa protein. Inactivation resulted formation long chains by cells, markedly decreased autolytic capacity, poor biofilm formation, diminished tolerance acid oxidative stress, production extracellular DNA (eDNA). biofilm-forming capacity mutant could be almost completely restored to strain adding purified recombinant AtlA mutans but only partially addition eDNA. Autolysis, eDNA release, expression increased sharply when cells entered stationary phase greatly enhanced growing aeration. LytST VicRK two-component systems both required for induction aeration, LytT able bind promoter region vitro. Thus, its associated regulatory cascade dominantly control phenotypes are critical colonization, persistence, competition other commensal pathogenic oral bacteria response redox environment growth