产河鲀毒素细菌水平转移相关基因的鉴定

多种进化关系并不密切的细菌均能合成河鲀毒素,揭示了产河鲀毒素细菌间可能存在水平基因转移现象,但通过何种途径并不清楚。为调查产河鲀毒素的气单胞菌(Aeromonas sp.)质粒中是否存在与水平基因转移相关的元件,通过PCR扩增分别发现该质粒中存在tra,rum及vird4基因,扩增出的906 bp的tra,681bp的rum及1 319 bp的vird4,分别与多种菌株的转座酶、松弛酶和Ⅳ型分泌系统中的ATP酶基因具有高度的序列同源性,并具有这些酶的保守结构域,结果表明产河鲀毒素的气单胞菌具有通过接合转移和转座方式转移基因的能力,同时具有转移河鲀毒素至宿主的能力。对于进一步了解产河鲀毒素细菌之间以及产河鲀毒素细菌与河鲀之间的关系有重要的帮助。研究亮点:本研究首次在产河鲀毒素的气单胞菌质粒中明确鉴定出与水平转移相关的基因,表明该细菌不但具有通过接合转移和转座方式转移基因的能力,而且具有转移河鲀毒素至宿主的能力。

Identification of HGT related genes in plasmid pNe-1 from tetrodotoxin producing Aeromonas sp.

Many unrelated bacteria in phylogenetic relationship with TTX producing ability were isolated from various animals and environment, reminding us that horizontal gene transfer (HGT) might exist among various TTX producing bacteria, but the exact mechanism is unclear. The objective of this study is to investigate whether HGT related genes exist in the plasmid pNe-1 isolated from tetrodotoxin producing Aeromonas sp. The tra, rum and vird₄ genes were amplified by PCR. The 906 bp length tra fragment, 681 bp length rum fragment and 1 319 bp length vird₄ fragment had significant homology to some transposase, relaxase and vird₄ in sequence and contained conserved domains of these putative proteins respectively. The results indicate that the tetrodotoxin producing Aeromonas sp. has the ability to transfer genes by conjugation and transposition, and also has the ability to transfer TTX to the hosts. The result of research in this study is believed to be significant for the further understanding of the relationship among tetrodotoxin producing bacteria and the relationship between tetrodotoxin producing bacteria and the puffer fish.