Stack Helena M, Sleator Roy D, Bowers Megan, Hill Colin, Gahan Cormac G M
Department of Microbiology and Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland.
Appl Environ Microbiol. 2005 Aug;71(8):4241-7. doi: 10.1128/AEM.71.8.4241-4247.2005.
In silico analysis of the Listeria monocytogenes genome revealed lmo0292, a gene predicted to encode a HtrA-like serine protease. A stable insertion mutant was constructed, revealing a requirement for htrA in the listerial response to heat, acid, and penicillin stress. Transcriptional analysis revealed that htrA is not induced in response to heat shock but is induced in response to low pH and penicillin G stress. Furthermore, htrA expression was shown to be dependent upon the LisRK two-component sensor-kinase, a system known to respond to changes in integrity of the cell envelope. In addition, we demonstrated that a second in-frame start codon, upstream of that previously annotated for L. monocytogenes htrA, incorporating a putative signal sequence appears to influence virulence potential. Finally, a significant virulence defect was observed for the htrA mutant, indicating that this gene is required for full virulence in mice. Our findings suggest that L. monocytogenes lmo0292 encodes an HtrA-like serine protease that is not part of the classical heat shock response but is involved in stress responses and virulence.
对单核细胞增生李斯特菌基因组进行的计算机分析揭示了lmo0292基因，该基因被预测编码一种类似HtrA的丝氨酸蛋白酶。构建了一个稳定的插入突变体，结果显示在李斯特菌对热、酸和青霉素应激的反应中htrA是必需的。转录分析表明，htrA不会因热休克而被诱导，但会因低pH值和青霉素G应激而被诱导。此外，已证明htrA的表达依赖于LisRK双组分传感激酶，该系统已知对细胞膜完整性的变化作出反应。此外，我们证明，在先前注释的单核细胞增生李斯特菌htrA上游的第二个读码框起始密码子，包含一个假定的信号序列，似乎会影响毒力潜力。最后，观察到htrA突变体存在显著的毒力缺陷，表明该基因是小鼠完全毒力所必需的。我们的研究结果表明，单核细胞增生李斯特菌lmo0292编码一种类似HtrA的丝氨酸蛋白酶，它不是经典热休克反应的一部分，但参与应激反应和毒力。
