Echenique J R, Chapuy-Regaud S, Trombe M C
Laboratoire de Genétique et Physiologie Bactérienne, Centre Hospitalo Universitaire de Rangueil, Université Paul Sabatier 31403 Toulouse cedex, France.
Mol Microbiol. 2000 May;36(3):688-96. doi: 10.1046/j.1365-2958.2000.01891.x.
Anaerobic aerotolerant Streptococcus pneumoniae modulates its genetic transformability and its virulence in response to the oxygen concentration. The activity of a single protein encoded by nox and showing NADH oxidase activity is involved in these adaptive responses to O2. Northern blot analysis of wild-type cultures grown under aerobic and microaerobic conditions indicated transcriptional control of comCDE by O2. An O2-independent mutant strain carrying the gain-of-function mutation comE38KE was isolated and its analysis showed that ComE is a key point in competence stimulation by O2. Plasmid insertion mutations in ciaRH revealed that this two component signal-transducing system negatively regulates comCDE transcription. The level of comCDE transcripts appears as a major control point in competence regulation by O2 and also by growth phase and cell density.
耐氧厌氧的肺炎链球菌会根据氧气浓度调节其遗传转化能力和毒力。由nox编码的具有NADH氧化酶活性的单一蛋白质的活性参与了这些对氧气的适应性反应。对在需氧和微需氧条件下生长的野生型培养物进行Northern印迹分析表明，comCDE受氧气的转录调控。分离出携带功能获得性突变comE38KE的不依赖氧气的突变菌株，其分析表明ComE是氧气刺激感受态的关键点。ciaRH中的质粒插入突变表明，这个双组分信号转导系统负向调节comCDE转录。comCDE转录本的水平似乎是氧气、生长阶段和细胞密度调节感受态的主要控制点。
