The Major Autolysin of Streptococcus gordonii Is Subject to Complex Regulation and Modulates Stress Tolerance, Biofilm Formation, and Extracellular-DNA Release
The Major Autolysin of Streptococcus gordonii Is Subject to Complex Regulation and Modulates Stress Tolerance, Biofilm Formation, and Extracellular-DNA Release
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DOI：
10.1128/jb.00056-11
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发表时间：
2011-06-01
影响因子：
3.2
通讯作者：
Burne, Robert A.
中科院分区：
文献类型：
--
作者：
Liu, Yaling;Burne, Robert A.
一个基因，命名为atlS，编码一个主要的自溶素从戈登链球菌，被确定和表征。该蛋白由1,160个氨基酸组成，分子量为127 kDa，具有一个保守的β 1，4-N-乙酰胞壁酶结构域。野生型S. gordonii显示出在atlS缺失突变体中不存在的分子量为130和90 kDa的肽聚糖水解酶活性。Western blotting显示90-kDa条带来自130-kDa蛋白。atlS的失活导致细胞形成长链，自溶能力显着降低，生物膜形成较差，对酸和氧化应激的耐受性降低，以及细胞外DNA（eDNA）的产生减少。通过添加纯化的重组S. atlS自溶素，atlS突变株的生物被膜形成能力几乎可以完全恢复到野生型菌株的水平。但通过添加eDNA仅部分恢复。自溶，eDNA的释放，atlS的表达急剧增加时，细胞进入稳定期，并大大提高了细胞生长与通风。LytST和VicRK双组分系统都是通过通气诱导atlS所必需的，并且纯化的LytT能够在体外结合atlS的启动子区域。因此，SINS及其相关的调节级联主要控制S的表型。戈登氏菌，其对于响应于氧化还原环境和生长结构域的定殖、持久性和与其他口腔和致病性口腔细菌的竞争至关重要。
A gene, designated atlS, encoding a major autolysin from Streptococcus gordonii, was identified and characterized. The predicted AtlS protein is 1,160 amino acids and 127 kDa and has a conserved beta 1,4-N-acetylmuramidase domain. Zymographic analysis of wild-type S. gordonii revealed peptidoglycan hydrolase activities with molecular masses of 130 and 90 kDa that were absent in an atlS deletion mutant. Western blotting revealed that the 90-kDa band was derived from the 130-kDa protein. Inactivation of atlS resulted in formation of long chains by the cells, markedly decreased autolytic capacity, poor biofilm formation, diminished tolerance of acid and oxidative stress, and decreased production of extracellular DNA (eDNA). The biofilm-forming capacity of the atlS mutant could be almost completely restored to that of the wild-type strain by adding purified recombinant AtlA autolysin of S. mutans but was only partially restored by addition of eDNA. Autolysis, eDNA release, and atlS expression increased sharply when cells entered stationary phase and were greatly enhanced in cells growing with aeration. The LytST and VicRK two-component systems were both required for the induction of atlS by aeration, and purified LytT was able to bind to the promoter region of atlS in vitro. Thus, AtlS and its associated regulatory cascade dominantly control phenotypes of S. gordonii that are critical to colonization, persistence, and competition with other commensal and pathogenic oral bacteria in response to the redox environment and growth domain.