Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv 69978, Israel.
Cell. 2012 Aug 17;150(4):792-802. doi: 10.1016/j.cell.2012.06.036.
The DNA uptake competence (Com) system of the intracellular bacterial pathogen Listeria monocytogenes is considered nonfunctional. There are no known conditions for DNA transformation, and the Com master activator gene, comK, is interrupted by a temperate prophage. Here, we show that the L. monocytogenes Com system is required during infection to promote bacterial escape from macrophage phagosomes in a manner that is independent of DNA uptake. Further, we find that regulation of the Com system relies on the formation of a functional comK gene via prophage excision. Prophage excision is specifically induced during intracellular growth, primarily within phagosomes, yet, in contrast to classic prophage induction, progeny virions are not produced. This study presents the characterization of an active prophage that serves as a genetic switch to modulate the virulence of its bacterial host in the course of infection.
胞内细菌病原体李斯特菌的 DNA 摄取能力（Com）系统被认为是不起作用的。目前还没有已知的 DNA 转化条件，而且 Com 主激活基因 comK 被温和噬菌体中断。在这里，我们表明李斯特菌的 Com 系统在感染过程中是必需的，以促进细菌以一种不依赖于 DNA 摄取的方式从巨噬细胞吞噬体中逃逸。此外，我们发现 Com 系统的调节依赖于通过噬菌体切除形成功能正常的 comK 基因。噬菌体切除在细胞内生长过程中特异性诱导，主要在吞噬体中，但与经典噬菌体诱导相反，不产生子代病毒粒子。本研究描述了一种活性噬菌体的特征，它作为一种遗传开关，在感染过程中调节其细菌宿主的毒力。
