Competence-Dependent Endogenous DNA Rearrangement and Uptake of Extracellular DNA Give a Natural Variant of Streptococcus mutans without Biofilm Formation
Competence-Dependent Endogenous DNA Rearrangement and Uptake of Extracellular DNA Give a Natural Variant of Streptococcus mutans without Biofilm Formation
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DOI：
10.1128/jb.05240-11
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发表时间：
2011-10-01
影响因子：
3.2
通讯作者：
Senpuku, Hidenobu
中科院分区：
文献类型：
--
作者：
Narisawa, Naoki;Kawarai, Taketo;Senpuku, Hidenobu
水不溶性葡聚糖（WIG）的产生使变形链球菌能够在口腔生态位中存活并持续存在。WIG是由高度同源的gtfB和gtfC基因串联编码的葡萄糖转移酶从蔗糖中产生的。相反，利用RecA很容易从gtfB和gtfC的内源性重组中产生一个单一的杂交基因，产生S. mutans UA159 WIG(-)（率接近1.0 × 10(-3)）。肺炎球菌recA基因作为一种晚期能力基因受到调控。comX基因突变未导致WIG（-）细胞的出现。流式细胞收集的生物膜中WIG（-）细胞比浮游细胞多。浮游细胞中，WIG（-）细胞在培养16 h后出现，培养32 h后增加了10倍左右，说明浮游细胞WIG（-）细胞在培养时间较长后增加。菌株可能来源于生物膜环境。在与供体WIG（+）和受体WIG（-）细胞共培养时，受体细胞恢复为WIG(+)，并从环境中获得完整的gtfBC区域，表明细胞外DNA的摄取导致表型改变。在这里，我们证明了内源性DNA重排和细胞外DNA的摄取产生WIG（-）细胞，两者都是由相同的信号换能器com系统诱导的。我们的发现可能有助于理解变形链球菌如何适应口腔环境，并可能解释变形链球菌的进化。
The production of water-insoluble glucan (WIG) enables Streptococcus mutans to survive and persist in the oral niche. WIG is produced from sucrose by glucosyltransferase encoded tandemly by the highly homologous gtfB and gtfC genes. Conversely, a single hybrid gene from the endogenous recombination of gtfB and gtfC is easily generated using RecA, resulting in S. mutans UA159 WIG(-) (rate of similar to 1.0 x 10(-3)). The pneumococcus recA gene is regulated as a late competence gene. comX gene mutations did not lead to the appearance of WIG(-) cells. The biofilm collected from the flow cell had more WIG(-) cells than among the planktonic cells. Among the planktonic cells, WIG(-) cells appeared after 16 h and increased similar to 10-fold after 32 h of cultivation, suggesting an increase in planktonic WIG(-) cells after longer culture. The strain may be derived from the biofilm environment. In coculture with donor WIG(+) and recipient WIG(-) cells, the recipient cells reverted to WIG(+) and acquired an intact gtfBC region from the environment, indicating that the uptake of extracellular DNA resulted in the phenotypic change. Here we demonstrate that endogenous DNA rearrangement and uptake of extracellular DNA generate WIG(-) cells and that both are induced by the same signal transducer, the com system. Our findings may help in understanding how S. mutans can adapt to the oral environment and may explain the evolution of S. mutans.