Tran L S, Nagai T, Itoh Y
Division of Applied Microbiology, National Food Research Institute, Ministry of Agriculture, Forestry and Fisheries, Kannondai 2-1-2, Tsukuba 305-8642, Japan.
Mol Microbiol. 2000 Sep;37(5):1159-71. doi: 10.1046/j.1365-2958.2000.02069.x.
In Bacillus subtilis, the ComQXPA quorum-sensing system controls cell density-dependent phenotypes such as the production of degradative enzymes and antibiotics and the development of genetic competence. Bacillus subtilis (natto) NAF12, a mutant defective in poly-gamma-glutamate (gamma-PGA) production, was derived from B. subtilis (natto) NAF4 by Tn917-LTV1 insertional mutagenesis. Determination of the mutant DNA sequences flanking the Tn917-LTV1 insert revealed that the insertion had inactivated comP in this mutant, indicating that gamma-PGA synthesis in B. subtilis (natto) is under the control of the ComP-ComA signal transduction system. A comparison of the amino acid sequences revealed striking variation in the primary structures of ComQ (44% identity), ComX (26%) and the sensor domain of ComP (36%) between B. subtilis (natto) NAF4 and B. subtilis 168. In contrast, the amino acid and nucleotide sequences of the kinase domains of ComP and of the ComA response regulator share 95% and 100% identity respectively. The comP genes of NAF4 and 168 restored the impaired competence of B. subtilis BD1658 (comP:cat) and gamma-PGA production of B. subtilis (natto) NAF12 (comP:Tn917-LTV1) to only 15% of the level achieved by the respective parent comP genes. However, when introduced together with the cognate comQ and comX genes, the comP genes restored the relevant defect of the heterologous comP mutants nearly to wild-type levels. Analogous to the comCDE system of Streptococcus strains and the agrBCDE system of Staphylococcus aureus, the concerted variation in the comQXP genes appears to establish specific intercellular communication between B. subtilis strains sharing the same pheromone system.
在枯草芽孢杆菌中，ComQXPA群体感应系统控制细胞密度依赖性表型，如降解酶和抗生素的产生以及遗传感受态的发育。枯草芽孢杆菌（纳豆芽孢杆菌）NAF12是一株多聚γ-谷氨酸（γ-PGA）产生缺陷的突变体，它是通过Tn917-LTV1插入诱变从枯草芽孢杆菌（纳豆芽孢杆菌）NAF4衍生而来的。对Tn917-LTV1插入位点两侧的突变体DNA序列进行测定，结果显示该插入使此突变体中的comP失活，这表明枯草芽孢杆菌（纳豆芽孢杆菌）中的γ-PGA合成受ComP-ComA信号转导系统的控制。氨基酸序列比较显示，枯草芽孢杆菌（纳豆芽孢杆菌）NAF4和枯草芽孢杆菌168之间的ComQ（44%同一性）、ComX（26%）以及ComP的传感结构域（36%）的一级结构存在显著差异。相比之下，ComP的激酶结构域和ComA应答调节子的氨基酸和核苷酸序列分别具有95%和100%的同一性。NAF4和168的comP基因仅将枯草芽孢杆菌BD1658（comP:cat）受损的感受态以及枯草芽孢杆菌（纳豆芽孢杆菌）NAF12（comP:Tn917-LTV1）的γ-PGA产生恢复至各自亲本comP基因所达到水平的15%。然而，当与同源的comQ和comX基因一起导入时，comP基因几乎将异源comP突变体的相关缺陷恢复至野生型水平。类似于链球菌菌株的comCDE系统和金黄色葡萄球菌的agrBCDE系统，comQXP基因的协同变异似乎在共享相同信息素系统的枯草芽孢杆菌菌株之间建立了特定的细胞间通讯。
