El Tor霍乱弧菌双精氨酸转运系统功能单位的分析研究

摘要

This paper aims to determine the minimum functional unit of twin-arginine translocation (Tat) system by analyzing the Tat system gene cluster composition, which was deduced by homology comparison between Tat gene cluster of Escherichia coli (,E. coli) K12 and Vibriocholerae ( V. cholerae) N16961. Tat mutant strains were constructed by deletion. Tat system minimum functional unit was then defined by comparing the phenotypes of Tat deletion strains, complement strains and wild type strain. The data showed that the Tat system gene cluster of V. cholerae N16961 consisted of tatA, tatB, tatC and tatA2, among which, tatA, tatB and tatC were located in the chromosome I and tatA2 gene was located in the chromosome II. The tatB and tatC genes were indispensable for Tat system functions, while tatA2 might play a role similar to talE in E. coli. The tatB and tatC combined together constitutes the minimum functional unit of V. cholera Tat system. tatA and tatA2 have similar functions and may share the same functional role in the Tat system.%本文旨在分析El Tor霍乱弧菌双精氨酸转运(Tat)系统的基因簇构成,对其功能进行分析,确定其最小功能单位.通过与大肠埃希菌Tat系统基因簇的基因同源性比较,推测霍乱国际测序标准株N16961的Tat系统基因簇构成；分别对霍乱弧菌Tat系统的基因簇进行单基因缺失、双基因缺失和全基因缺失,建立缺失株和回补株,并与野生株进行表型比较,进一步分析霍乱弧菌Tat系统的基因构成和最小功能单位.结果 显示,霍乱弧菌Tat系统基因簇由tatA、tatB、tatC、tatA2 4个基因构成,其中tatA、tatB和tatC基因位于霍乱弧菌Ⅰ号染色体,tatA2基因位于霍乱弧菌Ⅱ号染色体.tatB和tatC基因缺失影响霍乱弧菌Tat系统功能,tatA或tatA2单基因缺失后均可基本保持Tat系统功能,但同时缺失则导致菌株Tat系统功能丧失.提示霍乱弧菌Tat系统最小功能单位是tatA-tatB-tatC或tatA2 -tatB-tatC,tatA与tatA2功能重复.