Characterization of two putative mechanosensitive channel proteins of Campylobacter jejuni involved in protection against osmotic downshock
Characterization of two putative mechanosensitive channel proteins of Campylobacter jejuni involved in protection against osmotic downshock
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DOI：
10.1016/j.vetmic.2012.04.044
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发表时间：
2012-11-09
影响因子：
3.3
通讯作者：
Takai, Shinji
中科院分区：
文献类型：
--
作者：
Kakuda, Tsutomu;Koide, Yuuki;Takai, Shinji
急性低渗应激成为环境中细菌生存的威胁。机械敏感性通道在低渗休克期间维持细菌细胞完整性中起重要作用。数据库检索表明，空肠弯曲杆菌是全球范围内引起人类细菌性胃肠炎的主要原因，在C.空肠菌株81-176。低渗休克实验表明，缺乏Cjj 0263的突变体表现出严重的缺陷，在低渗休克的生存，而缺乏Cjj 1025的突变体表现出相同的生存能力，野生型。我们使用一日龄小鸡模型进一步检查了每个突变体的定殖能力。Cjj 0263或Cjj 1025突变体能够以与野生型相同的水平定殖鸡盲肠，但Cjj 0263 Cjj 1025双突变体显示定殖鸡盲肠的能力显著降低。检验C.已经在雏鸡消化道中生长的空肠被保护免受急性低渗应激，盲肠中的细菌直接暴露于水。野生型是能够生存的急性渗透压下调，但Cjj 0263突变体遭受了重大损失的活力时，受到一个快速的渗透压下调。免疫印迹分析表明，Cjj 0263和Cjj 1025都是通过N-连接的蛋白质糖基化途径糖基化的，但这些蛋白质的聚糖修饰不太可能对其功能和稳定性产生重大影响。我们的数据表明，Cjj 0263，机械敏感通道，在保护环境传输过程中经历的低渗应激具有举足轻重的作用。(C)2012爱思唯尔有限公司版权所有。
Acute hypotonic stress becomes a threat to the survival of bacteria in the environment. Mechanosensitive channels play an essential role in the maintenance of bacterial cell integrity during hypoosmotic shock. A database search suggested that Campylobacter jejuni, a major worldwide cause of bacterial gastroenteritis in humans, possesses two putative mechanosensitive channels, designated Cjj0263 and Cjj1025, in C. jejuni strain 81-176. Osmotic downshock experiments demonstrated that a mutant lacking Cjj0263 showed a severe defect in survival of hypoosmotic shock, while a mutant lacking Cjj1025 exhibited the same survival capacity as the wild type. We further examined the colonization ability of each mutant using the one-day old chick model. Cjj0263 or Cjj1025 mutants were able to colonize chick ceca at the same level as the wild type, but a Cjj0263 Cjj1025 double mutant revealed significantly reduced ability to colonize chick ceca. To examine whether C. jejuni that have grown in the digestive tract of chicks are protected against acute hypotonic stress, bacteria in ceca were directly exposed to water. The wild type was able to survive acute osmotic downshift, but the Cjj0263 mutant suffered a substantial loss of viability when subjected to a rapid osmotic downshock. Immunoblot analysis suggested that both Cjj0263 and Cjj1025 were glycosylated via the N-linked protein glycosylation pathway, but glycan modification of these proteins was unlikely to have a major effect on their function and stability. Our data suggest that Cjj0263, a mechanosensitive channel, has a pivotal role in protection against hypoosmotic stress experienced during environmental transmission. (C) 2012 Elsevier B.V. All rights reserved.