htrA和clpP基因缺失对变异链球菌铁代谢的影响

摘要

目的 探讨高温需要蛋白A (htrA)和酪蛋白裂解酶P(clpP)单基因缺失对变异链球菌铁代谢的影响.方法 采用浊度法测定变异链球菌标准株、htrA缺陷株和clpP缺陷株在0.1、0.2及0.3 mmol/L铁限制条件培养基中培养24h的吸光度(A)值,并测定加入外源性铁或标准株分别与2种缺陷株在0.3 mmol/L铁限制培养基中混合培养24h后的A值.结果 与标准株相比,htrA缺陷株在浓度0.3 mmol/L时A值差异有统计学意义(P＜ 0.01)；clpP缺陷株在0.2mmol/L时A值差异即有统计学意义(P＜0.05),并且其值随铁螯合剂浓度的增加而减小.加入FeSO4培养24 h,htrA缺陷株与标准株A值差异无统计学意义(P＞0.05)；clpP缺陷株的A值低于标准株(1.002±0.014 vs1.325±0.010,P＜0.05).与标准株按1∶1比例混合培养24 h,htrA缺陷株与其单独生长时的A值的差异无统计学意义(P＞0.05)；clpP缺陷株的A值高于其单独培养时的A值(10.878±0.005 vs 0.664±0.006),差异有统计学意义(P＜0.05).结论 htrA和clpP基因分别在一定程度上影响变异链球菌的铁代谢.%Objective To study the effect of inactivation of high temperature requirement A (htrA) or caseinolytic protease P (clpP) on the iron metabolism of Streptococcus mutans.Methods The nephelometer method was used to measure the absorbance of iron-limited defined medium in which Streptococcus mutans standard strains or htrA, clpP mutant strains were cultured for 24 hours.And the absorbance of all three strains was also measured and analyzed in the iron-limited defined medium with exogenous iron added or mutant and standard strains co-cultured in proportion to 1: 1 for 24 hours.Results Compared to the standard strains, the growth of htrA mutant strains was not significantly affected until the concentration of iron chelator increased to 0.3 mmol/L (P < 0.05).The growth of clpP mutant strains was significantly affected in medium containing 0.2 mmol/L iron chelator (P < 0.05).The growth inhibition of mutant strains showed varying degrees of reversal when added exogenous iron to the iron-limited medium or 1:1 co-cultured with standard strains.Conclusion htrA gene or clpP gene plays an important role in iron metabolism of Streptococcus mutans.