...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Infection and immunity >Identification and characterization of a K88- and CS31A-like operon of a rabbit enteropathogenic Escherichia coli strain which encodes fimbriae involved in the colonization of rabbit intestine.
【24h】

Identification and characterization of a K88- and CS31A-like operon of a rabbit enteropathogenic Escherichia coli strain which encodes fimbriae involved in the colonization of rabbit intestine.

机译：鉴定和鉴定了兔肠道致病性大肠杆菌菌株的K88和CS31A样操纵子，该菌株编码参与兔小肠定殖的菌毛。

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Initiation of attaching-effacing lesions, which characterize infections with rabbit enteropathogenic Escherichia coli (REPEC), requires bacteria to adhere to the intestinal epithelium. This adherence is reflected in vitro by the affinity of these E. coli strains for various types of eukaryotic cells. TnphoA mutants of REPEC 83/39 (O15:H-) which had lost the ability to adhere to HEp-2 epithelial cells, guinea pig ileal brush borders, and mouse erythrocytes were generated. DNA sequencing of the region surrounding the inactivating transposon insertions within a 95-kb plasmid, designated pRAP for REPEC adherence plasmid, revealed extensive homology between that region and the structural genes of enterotoxigenic E. coli operons encoding the K88 and CS31A fimbrial adhesins and the genes for the afr2 adhesin from REPEC B10 (O103:H2). Seven genes of the ral operon (for REPEC adherence locus), including three putative minor fimbrial subunit genes (ralC, ralF, and ralH), a major fimbrial subunit gene (ralG), a gene of unknown function (ralI), and genes for two fimbrial subunit chaperones (ralD and ralE), were sequenced. When inoculated perorally into weanling rabbits, a mutant with a TnphoA insertion in the ralE gene showed a 10-fold reduction in colonizing ability, with only 1 of 10 rabbits excreting bacteria compared to all 5 of those infected with the wild-type parent strain (P = 0.002). The severity of the diarrheal illness caused by the mutant strain was also reduced. Western blotting of surface protein extracts of strain 83/39 with hyperimmune anti-83/39 antiserum, adsorbed with the ralE mutant, revealed a 32-kDa protein which was absent from protein extracts of two nonadherent mutants. The adsorbed antiserum also bound to the surface of strain 83/39 but not to nonadherent mutants, as detected by immunogold labeling. These results indicate that the ral operon of REPEC 83/39 contains genes necessary for the biosynthesis of fine fimbriae which are responsible for in vitro adherence of the bacteria and play a role in their colonization of, and hence virulence for, rabbits. The putative major fimbrial subunit is a protein with an observed molecular size of approximately 32 kDa which, when assembled, appears to form a capsule of fimbriae surrounding the bacterium similar to that described for CS31A.
机译：附着性病变的开始是兔子肠道致病性大肠杆菌（REPEC）感染的特征，它需要细菌粘附在肠上皮上。这些大肠杆菌菌株对各种类型的真核细胞的亲和力在体外反映出这种依从性。产生了REPEC 83/39（O15：H-）的TnphoA突变体，该突变体失去了粘附于HEp-2上皮细胞，豚鼠回肠刷缘和小鼠红细胞的能力。 95 kb质粒中的失活转座子插入区域周围的DNA测序（称为REPEC粘附质粒的pRAP）显示该区域与编码K88和CS31A纤维粘附素的产肠毒素大肠杆菌操纵子的结构基因和这些基因之间具有广泛的同源性REPEC B10（O103：H2）中的afr2粘附素。 ral操纵子的7个基因（用于REPEC粘附位点），包括3个假定的次要纤维亚基基因（ralC，ralF和ralH），主要纤维亚基基因（ralG），功能未知的基因（ralI）和对两个纤维亚基分子伴侣（ralD和ralE）进行了测序。当将其经口接种到断奶的兔子中时，在ralE基因中插入TnphoA的突变体显示出其定殖能力降低了10倍，与之相比，所有5只感染了野生型亲本菌株的兔子中，只有10只兔子排泄细菌（ P = 0.002）。由突变菌株引起的腹泻病的严重性也降低了。用ralE突变体吸附的超免疫性抗83/39抗血清对83/39菌株表面蛋白提取物进行的蛋白质印迹显示，两个非粘附突变体的蛋白提取物中不存在32 kDa蛋白。如通过免疫金标记检测到的，吸附的抗血清也结合至菌株83/39的表面，但不结合至非粘附突变体。这些结果表明，REPEC 83/39的Ral操纵子包含细菌毛的生物合成所必需的基因，这些基因负责细菌的体外粘附，并在其对兔子的定殖以及因此对兔子的毒性中起作用。推定的主要纤维亚基是一种蛋白质，其观察到的分子大小约为32 kDa，组装后似乎形成围绕细菌的菌毛囊，类似于CS31A所述。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号