A STREPTOCOCCUS-MUTANS MUTANT THAT SYNTHESIZES ELEVATED LEVELS OF INTRACELLULAR POLYSACCHARIDE IS HYPERCARIOGENIC IN-VIVO
A STREPTOCOCCUS-MUTANS MUTANT THAT SYNTHESIZES ELEVATED LEVELS OF INTRACELLULAR POLYSACCHARIDE IS HYPERCARIOGENIC IN-VIVO
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DOI：
10.1128/iai.63.7.2556-2563.1995
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发表时间：
1995-07-01
影响因子：
3.1
通讯作者：
MICHALEK, S
中科院分区：
文献类型：
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作者：
SPATAFORA, G;ROHRER, K;MICHALEK, S
我们使用链球菌转座子Tn916来鉴定和分离具有改变的细胞内多糖（IPS）积累的变形链球菌突变体。本文报道了S. mutans SMS202，一种转座子突变体，其积累的糖原样IPS超过野生型水平。Southern印迹分析证实了单个Tn916插入到SMS 202染色体中。此外，定量超微结构分析显示，相对于野生型祖菌株UA130，在SMS202中IPS的浓度显著增加。在IPS过量突变体中，细菌IPS生物合成所需的ADP葡萄糖焦磷酸化酶（GlgC）和糖原合成酶（GlgA）的活性也升高。此外，SMS202在无菌大鼠磨牙表面的致龋性显著高于野生型（P < 0.01），从而证实了IPS在S.突变体诱导的龋齿形成。我们提出，增加致龋潜力的SMS202是由于组成型表达的基因编码糖原生物合成在这种口腔病原体。GlgC和GlgA的协调表达沿着正在进行的核苷酸序列分析和北方杂交实验的结果支持这种口腔病原体的glg基因的操纵子样排列。
We used the streptococcal transposon, Tn916 to identify and isolate mutants of Streptococcus mutans with altered intracellular polysaccharide (IPS) accumulation. We report on the isolation and characterization of S. mutans SMS202, a transposon mutant which accumulated the glycogen-like IPS in excess of wild-type levels. Southern blot analysis confirmed a single Tn916 insertion into the SMS202 chromosome. Moreover, quantitative ultrastructural analysis revealed significantly increased concentrations of IPS in SMS202 relative to those of the wild-type progenitor strain, UA130. The activities of ADPglucose pyrophosphorylase (GlgC) and glycogen synthase (GlgA), enzymes required for the biosynthesis of bacterial IPS, were also elevated in the IPS excess mutant. Furthermore, SMS202 was significantly more cariogenic on the molar surfaces of germ-free rats than the wild type (P < 0.01), thus confirming a central role for IPS in S. mutans-induccd caries formation. We propose that the increased cariogenic potential of SMS202 is due to constitutive expression of genes which encode glycogen biosynthesis in this oral pathogen. The coordinate expression of GlgC and GlgA along with the results of ongoing nucleotide sequence analysis and Northern hybridization experiments support an operon-like arrangement for the glg genes of this oral pathogen.