Lancero Hope, Caberoy Nora B, Castaneda Schryl, Li Yinuo, Lu Ann, Dutton David, Duan Xue-yan, Kaplan Heidi B, Shi Wenyuan, Garza Anthony G
Molecular Biology Institute, University of California, Los Angeles, CA 90095-1668, USA.
Microbiology (Reading). 2004 Dec;150(Pt 12):4085-93. doi: 10.1099/mic.0.27381-0.
Myxococcus xanthus is a gliding bacterium that possesses two motility systems, the adventurous (A-motility) and social (S-motility) systems. A-motility is used for individual cell gliding, while S-motility is used for gliding in multicellular groups. Video microscopy studies showed that nla24 cells are non-motile on agar surfaces, suggesting that the nla24 gene product is absolutely required for both A-motility and S-motility under these assay conditions. S-motility requires functional type IV pili, wild-type LPS O-antigen, and an extracellular matrix of exopolysaccharide (EPS) and protein called fibrils. The results of expression studies and tethering assays indicate that the nla24 mutant has functional type IV pili. The nla24 mutant also produces wild-type LPS. However, several lines of evidence suggest that the nla24 mutant is defective for production of the EPS portion of the fibril matrix. The nla24 mutant is also defective for transcription of two genes (aglU and cglB) known to be required for A-motility, which is consistent with the idea that nla24 cells are defective for A-motility. Based on these findings, it is proposed that the putative transcriptional activator Nla24 regulates a subset of genes that are important for A-motility and S-motility in M. xanthus.
黄色粘球菌是一种具有两种运动系统的滑行细菌，即冒险性（A 运动性）和社会性（S 运动性）系统。A 运动性用于单个细胞的滑行，而 S 运动性用于多细胞群体中的滑行。视频显微镜研究表明，nla24 细胞在琼脂表面上不运动，这表明在这些检测条件下，nla24 基因产物对于 A 运动性和 S 运动性都是绝对必需的。S 运动性需要功能性的 IV 型菌毛、野生型脂多糖 O 抗原以及一种由胞外多糖（EPS）和称为纤丝的蛋白质组成的细胞外基质。表达研究和系留试验的结果表明，nla24 突变体具有功能性的 IV 型菌毛。nla24 突变体也产生野生型脂多糖。然而，几条证据表明，nla24 突变体在纤丝基质的 EPS 部分的产生方面存在缺陷。nla24 突变体在已知 A 运动性所需的两个基因（aglU 和 cglB）的转录方面也存在缺陷，这与 nla24 细胞在 A 运动性方面存在缺陷的观点一致。基于这些发现，有人提出推定的转录激活因子 Nla24 调节黄色粘球菌中对 A 运动性和 S 运动性重要的一部分基因。
