Fader R C, Duffy L K, Davis C P, Kurosky A
J Biol Chem. 1982 Mar 25;257(6):3301-5.
Type 1 pili were purified from a Klebsiella pneumoniae strain isolated from a human urinary tract infection. The pili were removed from the bacteria by mechanical shearing, precipitated out of solution by ammonium sulfate, solubilized in a deoxycholate-containing buffer, and finally purified by gel filtration. Chemical characterization of the isolated pili revealed a single protein subunit (pilin) which had a Mr = 21,500. Amino acid compositional analysis revealed a high content of residues that contribute significantly to secondary structure. Automated sequence analysis of the NH2-terminal region revealed a striking homology (79% identity) with type 1 pili of Escherichia coli. In contrast, NH2-terminal sequence comparison of K. pneumoniae pilin with other previously reported bacterial pilins showed no significant homology. No immunological cross-reactivity was detectable between E. coli and K. pneumoniae pili when tested by Ouchterlony double immunodiffusion or by rocket immunoelectrophoresis. The results of this study, when compared to other studies of bacterial pili, indicate that type 1 pili from members of the Enterobacteriaceae share morphological similarities and that their monomeric subunits are chemically similar. In addition, these results give strong evidence that the type 1 pilins of the enteric bacteria represent a separate class of homologous pilins.
1型菌毛从一株从人类尿路感染中分离出的肺炎克雷伯菌中纯化得到。通过机械剪切将菌毛从细菌中去除，用硫酸铵使其从溶液中沉淀出来，溶解于含脱氧胆酸盐的缓冲液中，最后通过凝胶过滤进行纯化。对分离得到的菌毛进行化学表征，发现其含有一种单一的蛋白质亚基（菌毛蛋白），其相对分子质量为21,500。氨基酸组成分析显示，对二级结构有显著贡献的残基含量很高。对氨基末端区域进行自动序列分析，发现其与大肠杆菌的1型菌毛有显著的同源性（79%的同一性）。相比之下，肺炎克雷伯菌菌毛蛋白的氨基末端序列与其他先前报道的细菌菌毛蛋白的序列比较未显示出显著的同源性。当通过双向免疫扩散或火箭免疫电泳进行检测时，未检测到大肠杆菌和肺炎克雷伯菌菌毛之间的免疫交叉反应。与其他关于细菌菌毛的研究相比，本研究结果表明，肠杆菌科成员的1型菌毛在形态上具有相似性，并且它们的单体亚基在化学上也相似。此外，这些结果有力地证明，肠道细菌的1型菌毛蛋白代表了一类单独的同源菌毛蛋白。
