comE基因缺陷影响肺炎链球菌体内诱导基因的表达

【目的】筛选受comE调控的肺炎链球菌(Streptococcus pneumoniae,S.pn)体内诱导基因。【方法】通过插入失活构建基因comE缺陷的S.pn菌株,与野生菌株分别腹腔注射BALB/c小鼠,经过体内诱导后取小鼠血,分离细菌提取RNA,用RT-PCR法检测13个体内诱导基因mRNA水平差异。【结果】将RT-PCR结果通过Quantity-one灰度分析,进行配对t检验,显示8个体内诱导基因在缺陷菌株和野生菌株中mRNA表达水平具有统计学差异(P0.05),其中spd-0300、spd-0414、spd-0622、spd-1663、spd-1719、spd-0235、spd-0873受转化上调,spd-1672受转化下调。【结论】筛选出受转化调控的体内诱导基因spd-0300、spd-0414、spd-0622、spd-1663、spd-1719、spd-0235、spd-0873、spd-1672,它们可能参与生长调节、温度感应、糖脂代谢等环节,表明细菌转化可通过调节某些体内诱导基因的表达来增强细菌的毒力。

comE-deficient mutant affects in vivo-induced genes expression in Streptococcus pneumoniae

Abstract: Objective] To screen in vivo genes of Streptococcus pneumoniae controlled by comE gene. Methods] The comE-deficient strain was constructed by using insertion inactivation and identified by PCR and sequencing. The BALB/c mouse was used as test animal and injected with D39 wild type and D39 comE-deficient strain via intraperitoneal injection. The mice blood was obtained about 24 hours after the injection through posterior orbital venous plexus approach. Then the bacteria induced in vivo were collected from the blood and their RNA were extracted to measure the mRNA expression levels of each in vivo-induced gene by RT-PCR. Results] The differences of the expressions of 8 in vivo-induced genes in D39 and D39 comE-deficient strain were statistically significant (P<0.05) and in which spd_0300, spd_0414, spd_0622, spd_1663, spd_1719, spd_0235, spd_0873 were up-regulated by transformation and meanwhile spd_1672 was down-regulated. Conclusion] In vivo-induced genes spd_0300, spd_0414, spd_0622, spd_1663, spd_1719, spd_0235, spd_0873, spd_1672 regulated by transformation were screened out and they may participate in the processes such as growth regulation, temperature reception, carbohydrate metabolism, and lipoids metabolism. The bacterial transformation may enhance the virulence via regulating some in vivo-induced genes expression.