Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 3-1, 7-Chome, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Microb Pathog. 2011 Sep;51(3):142-8. doi: 10.1016/j.micpath.2011.04.007. Epub 2011 Apr 27.
Staphylococcus aureus spreads on soft agar surfaces and forms giant colonies. Here, we examined the inhibitory role of extracellular DNA on the colony spreading activity. The double-deletion mutation of nuc1 and nuc2, which encode secretory nucleases, increased extracellular DNA and showed a decreased ability to form giant colonies. The addition of DNase I or micrococcal nuclease to the soft agar restored the ability of the nuc1-nuc2 double mutant to form giant colonies. In addition, the promoter activities of nuc1 and nuc2 in the wild-type strain were elevated in the peripheral region of the giant colony. These findings suggest that the digestion of extracellular DNA by secretory nucleases is required for the colony spreading activity of S. aureus.
金黄色葡萄球菌在软琼脂表面扩散并形成巨型菌落。在这里，我们研究了细胞外 DNA 对菌落扩散活性的抑制作用。编码分泌核酸酶的 nuc1 和 nuc2 的双缺失突变增加了细胞外 DNA，并显示出形成巨型菌落的能力降低。将 DNA 酶 I 或微球菌核酸酶添加到软琼脂中恢复了 nuc1-nuc2 双突变体形成巨型菌落的能力。此外，野生型菌株中 nuc1 和 nuc2 的启动子活性在巨型菌落的外周区域升高。这些发现表明，分泌核酸酶对细胞外 DNA 的消化是金黄色葡萄球菌菌落扩散活性所必需的。
