Gygi D, Bailey M J, Allison C, Hughes C
Cambridge University Department of Pathology, UK.
Mol Microbiol. 1995 Feb;15(4):761-9. doi: 10.1111/j.1365-2958.1995.tb02383.x.
Swarming by Proteus mirabilis is characterized by cycles of rapid population migration across surfaces, following differentiation of typical rods into long, aseptate swarm cells that overexpress flagella and virulence factors, particularly haemolysin. A non-swarming Tn5phoA mutant was unable to synthesize flagella, to fully elongate or to induce high levels of the toxin. The mutation lay within a 2091 bp gene encoding a homologue of the Escherichia coli FlhA belonging to a family of proteins that are required for assembly of flagella or virulence proteins and that are suggested to act either directly in membrane translocation and/or in regulating synthesis of the export apparatus. In trans expression of multicopy flhA restored cell elongation and migration and generated differentiation-specific hyperexpression of flagellin and toxin genes to levels above those seen in the wild-type strain. Transcription of flhA was strongly induced during differentiation, from its own putative sigma 28 promoter. The results suggest a mechanistic coupling of flagella assembly and swarm-cell differentiation.
奇异变形杆菌的群游运动特征为典型杆菌分化成长而无隔膜的群游细胞，这些细胞过度表达鞭毛和毒力因子，尤其是溶血素，随后群体迅速在表面迁移。一个非群游的Tn5phoA突变体无法合成鞭毛、完全伸长或诱导产生高水平毒素。该突变位于一个2091 bp的基因内，该基因编码大肠杆菌FlhA的同源物，FlhA属于鞭毛或毒力蛋白组装所需的蛋白质家族，据推测其直接作用于膜转运和/或调节输出装置的合成。多拷贝flhA的反式表达恢复了细胞伸长和迁移，并使鞭毛蛋白和毒素基因产生分化特异性的过度表达，表达水平高于野生型菌株。flhA的转录在分化过程中由其自身假定的σ28启动子强烈诱导。结果表明鞭毛组装与群游细胞分化存在机制上的耦合。
