Maher D, Sherburne R, Taylor D E
Department of Medical Microbiology and Infectious Diseases, University of Alberta, Edmonton, Canada.
J Bacteriol. 1993 Apr;175(8):2175-83. doi: 10.1128/jb.175.8.2175-2183.1993.
The kinetics of pilus outgrowth were examined for Escherichia coli containing pDT1942, a TnlacZ insertion derivative of the IncHI1 plasmid R27, which was derepressed for transfer. IncHI1 plasmids are thermosensitive for transfer. The pili specified by pDT1942 were examined by transmission electron microscopy after the pilus had been labeled with the H-pilus-specific bacteriophage Hgal, which had been inactivated with RNase A. H pili were extended by extrusion from the cell surface and not by the addition of pilin subunits to the pilus tip. After pili were removed by vortexing, the outgrowth of full-length pili (2 microns long) required 20 min. H pili expressed at the transfer optimal temperature (27 degrees C) remained stable after incubation at the transfer inhibitory temperature (37 degrees C), but the formation of mating aggregates was inhibited at 37 degrees C. Within 1 min of exposure of the host cell to a heat stimulus of 50 degrees C, pili vanished. Pili were observed in straight and flexible forms with a field emission scanning electron microscope, which may indicate a dynamic role for the pilus in conjugation.
对含有pDT1942的大肠杆菌的菌毛生长动力学进行了研究，pDT1942是IncHI1质粒R27的TnlacZ插入衍生物，其转移被去阻遏。IncHI1质粒对转移具有温度敏感性。在用经核糖核酸酶A灭活的H菌毛特异性噬菌体Hgal标记菌毛后，通过透射电子显微镜检查由pDT1942指定的菌毛。H菌毛通过从细胞表面挤出而延伸，而不是通过向菌毛尖端添加菌毛亚基。通过涡旋去除菌毛后，全长菌毛（2微米长）的生长需要20分钟。在转移最佳温度（27℃）下表达的H菌毛在转移抑制温度（37℃）下孵育后仍保持稳定，但在37℃下交配聚集体的形成受到抑制。在宿主细胞暴露于50℃热刺激的1分钟内，菌毛消失。用场发射扫描电子显微镜观察到菌毛呈直的和柔性的形式，这可能表明菌毛在接合中具有动态作用。
