SMU.746-SMU.747, a Putative Membrane Permease Complex, Is Involved in Aciduricity, Acidogenesis, and Biofilm Formation in Streptococcus mutans
SMU.746-SMU.747, a Putative Membrane Permease Complex, Is Involved in Aciduricity, Acidogenesis, and Biofilm Formation in Streptococcus mutans
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DOI：
10.1128/jb.00960-13
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发表时间：
2013-10
影响因子：
3.2
通讯作者：
J. Król;S. Biswas;Clay King;I. Biswas
中科院分区：
文献类型：
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作者：
J. Król;S. Biswas;Clay King;I. Biswas
摘要变形链球菌引起的龋病是世界范围内最常见的慢性感染性疾病之一。S.变形杆菌依赖于细菌在牙齿表面定居并在强酸性环境中生存的能力。我们进行了ISS 1转座子诱变筛选酸敏感突变体的S。746-SMU.747基因簇，其是耐酸所需的。SMU.746和SMU.747似乎被组织在一个操纵子中，并编码一个推定的膜相关通透酶。SMU.746-和SMU.747-缺陷突变体显示在酸化培养基中生长的能力降低。然而，突变体的短期或长期酸存活能力和F1 F0 ATP酶活性不受影响。此外，这两个基因的缺失并没有改变细胞膜的通透性和氧化和热应激反应。生长受到严重影响，即使轻微酸化的确定培养基（pH 6.5）。突变株在葡萄糖和蔗糖存在下生长期间酸化限定培养基的能力显著降低，尽管糖酵解速率仅受到轻微影响。令人惊讶的是，SMU.746-SMU.747基因的缺失引发了低pH培养基中生物膜形成的增加。在化学成分确定的培养基中观察到的效果更显著。我们推测SMU.746-SMU.747复合体负责氨基酸转运，并讨论了其在口腔环境中的定植和生存中可能发挥的作用。
ABSTRACT Dental caries induced by Streptococcus mutans is one of the most prevalent chronic infectious diseases worldwide. The pathogenicity of S. mutans relies on the bacterium's ability to colonize tooth surfaces and survive a strongly acidic environment. We performed an ISS1 transposon mutagenesis to screen for acid-sensitive mutants of S. mutans and identified an SMU.746-SMU.747 gene cluster that is needed for aciduricity. SMU.746 and SMU.747 appear to be organized in an operon and encode a putative membrane-associated permease. SMU.746- and SMU.747-deficient mutants showed a reduced ability to grow in acidified medium. However, the short-term or long-term acid survival capacity and F1F0 ATPase activity remained unaffected in the mutants. Furthermore, deletion of both genes did not change cell membrane permeability and the oxidative and heat stress responses. Growth was severely affected even with slight acidification of the defined medium (pH 6.5). The ability of the mutant strain to acidify the defined medium during growth in the presence of glucose and sucrose was significantly reduced, although the glycolysis rate was only slightly affected. Surprisingly, deletion of the SMU.746-SMU.747 genes triggered increased biofilm formation in low-pH medium. The observed effects were more striking in a chemically defined medium. We speculate that the SMU.746-SMU.747 complex is responsible for amino acid transport, and we discuss its possible role in colonization and survival in the oral environment.