Role of Vibrio cholerae exochitinase ChiA2 in horizontal gene transfer
Role of Vibrio cholerae exochitinase ChiA2 in horizontal gene transfer
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DOI：
10.1139/cjm-2015-0556
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发表时间：
2016-03-01
影响因子：
2.8
通讯作者：
Chatterjee, Nabendu Sekhar
中科院分区：
文献类型：
--
作者：
Mondal, Moumita;Chatterjee, Nabendu Sekhar
霍乱弧菌几丁质外切酶ChiA 2在自然环境中通过几丁质水解获得营养物质以及在肠道环境中的致病中起关键作用。在这项研究中，我们证明了ChiA 2在自然环境中水平基因转移的重要性。我们发现，表达的ChiA 2和TfoX，霍乱弧菌水平基因转移的中央调节器，随着环境条件的变化而变化。ChiA 2的活性也依赖于这些条件。在这里测试的3种不同的环境条件下，我们观察到ChiA 2的最大表达和活性的支持环境条件是20 ℃，pH 5.5，和100 mmol/L的盐度在几丁质的存在下。同样的条件也诱导TfoX表达，有利于霍乱弧菌的水平基因转移。高效液相色谱分析表明，在适宜的条件下，ChiA 2能从甲壳素水解中释放出大量的（GlcNAc）2。我们推测，在有利的环境条件下，ChiA 2被上调，并最大限度地从几丁质中产生大量的（GlcNAc）2。相同的环境条件也诱导tfoX表达，随后通过产生的（GlcNAc）2对其进行翻译激活，从而导致有效的水平基因转移。
Vibrio cholerae exochitinase ChiA2 plays a key role in acquisition of nutrients by chitin hydrolysis in the natural environment as well as in pathogenesis in the intestinal milieu. In this study we demonstrate the importance of ChiA2 in horizontal gene transfer in the natural environment. We found that the expression of ChiA2 and TfoX, the central regulator of V. cholerae horizontal gene transfer, varied with changes in environmental conditions. The activity of ChiA2 was also dependent on these conditions. In 3 different environmental conditions tested here, we observed that the supporting environmental condition for maximum expression and activity of ChiA2 was 20 degrees C, pH 5.5, and 100 mmol/L salinity in the presence of chitin. The same condition also induced TfoX expression and was favorable for horizontal gene transfer in V. cholerae. High-performance liquid chromatography analysis showed that ChiA2 released a significant amount of (GlcNAc) 2 from chitin hydrolysis under the favorable condition. We hypothesized that under the favorable environmental condition, ChiA2 was upregulated and maximally active to produce a significant amount of (GlcNAc) 2 from chitin. The same environmental condition also induced tfoX expression, followed by its translational activation by the (GlcNAc) 2 produced, leading to efficient horizontal gene transfer.