HtrA 对乳牙高致龋性变异链球菌 GTFs 表达及活性的影响

目的：研究乳牙高致龋性变异链球菌（S．mutans）高温需要 A 蛋白（HtrA）基因缺陷株和 HtrA 高毒力株在体外非应激环境中的葡萄糖基转移酶（GTFs）表达能力及其生物学活性的差异。方法：选用前期已获得的乳牙高致龋性 S．mutans HtrA 基因缺陷株和高毒力株（HtrA 高毒力株和 HtrA 基因缺陷株），在 BHI 培养基培养至指数期第10 h 后。以实时逆转录聚合酶链反应（real-time RT-PCR）方法检测2菌株 gtfB，gtfC，gtfD 的表达情况。提取蛋白，以蒽酮硫酸法检测其生物学活性，以蛋白免疫印迹（Western Blot）检测其表达量。结果：GTFs 蛋白和基因在乳牙 S．mutans HtrA 基因缺陷株中的表达高于 HtrA 高毒力株，但其生物学活性低于高毒力株。结论：HtrA 基因在乳牙 S．mutans GTFs 的分泌过程中起重要的调控作用。

The effects of HtrA on the expression and biological activity of GTFs of Streptococcus mutans isolated from children with high cario-susceptibility

Objective:To compare the expression and biological activity of glucosyl transferases (GTFs)of Streptococcus mutans (S.mutans)under normal outside environment between high temperature requirment serine proteinase A(HtrA)-deficient strains and high virulent strains isolated from children with high cario-susceptibility.Methods:The HtrA-deficient strains and high virulent strains of S.mutans were obtained by preliminary study.The strains were reanimated and incubated in BHI medium to exponential phase at tenth hour.The expression of gtfB,gtfC and gtfD were detected by real-time RT-PCR.The biological activity of the GTFs were detected by entong sulfuric acid method and Western Blot.Results:The expression of gtfs and GTFs in the HtrA-deficient strains was higher than those of high virulent strains,but the biological activity of the GTFs was lower.Conclusion:The HtrA gene plays an important regulatory role in the process of the GTFs expression of S.mutans isolated from children with high cario-susceptibility.