Centre of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20, 3001 Leuven, Belgium.
BMC Microbiol. 2010 Nov 2;10:276. doi: 10.1186/1471-2180-10-276.
LuxS is the synthase enzyme of the quorum sensing signal AI-2. In Salmonella Typhimurium, it was previously shown that a luxS deletion mutant is impaired in biofilm formation. However, this phenotype could not be complemented by extracellular addition of quorum sensing signal molecules.
Analysis of additional S. Typhimurium luxS mutants indicated that the LuxS enzyme itself is not a prerequisite for a wild type mature biofilm. However, in close proximity of the luxS coding sequence, a small RNA molecule, MicA, is encoded on the opposite DNA strand. Interference with the MicA expression level showed that a balanced MicA level is essential for mature Salmonella biofilm formation. Several MicA targets known to date have previously been reported to be implicated in biofilm formation in Salmonella or in other bacterial species. Additionally, we showed by RT-qPCR analysis that MicA levels are indeed altered in some luxS mutants, corresponding to their biofilm formation phenotype.
We show that the S. Typhimurium biofilm formation phenotype of a luxS mutant in which the complete coding region is deleted, is dependent on the sRNA molecule MicA, encoded in the luxS adjacent genomic region, rather than on LuxS itself. Future studies are required to fully elucidate the role of MicA in Salmonella biofilm formation.
LuxS 是群体感应信号 AI-2 的合成酶。先前在鼠伤寒沙门氏菌中表明，luxS 缺失突变体在生物膜形成方面受损。然而，这种表型不能通过细胞外添加群体感应信号分子来弥补。
对额外的 S. Typhimurium luxS 突变体的分析表明，LuxS 酶本身不是野生型成熟生物膜的先决条件。然而，在 luxS 编码序列的附近，在相反的 DNA 链上编码了一个小 RNA 分子 MicA。干扰 MicA 的表达水平表明，平衡的 MicA 水平对于成熟的沙门氏菌生物膜形成是必不可少的。迄今为止，已经报道了几个 MicA 靶标与沙门氏菌或其他细菌物种中的生物膜形成有关。此外，我们通过 RT-qPCR 分析表明，在一些 luxS 突变体中，MicA 水平确实发生了改变，这与它们的生物膜形成表型相对应。
我们表明，完全缺失编码区域的 luxS 突变体的 S. Typhimurium 生物膜形成表型依赖于编码在 luxS 相邻基因组区域的 sRNA 分子 MicA，而不是依赖于 LuxS 本身。需要进一步的研究来充分阐明 MicA 在沙门氏菌生物膜形成中的作用。
