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，确定其最小功能单位。通过与大肠埃希菌Tat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转运系统的基因构成和最小功能单位。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功能，但同时缺失导致菌株Tat功能丧失。结果提示，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。

The 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 Vibrio cholerae (V. cholerae) N16961. Tat mutant strains were constructed by deleting tat genes of the N16961 reference strain either individually or double genes combined together. Tat transport system minimum functional unit were then analyzed by comparing the phenotypes among Tat mutant strain, complement strain and wild 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 located in the chromosomeⅠand tatA₂ gene located in the chromosome Ⅱ. The tatB and tatC genes were indispensable for Tat system functions, while tatA₂ might play a role similar to tatE 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.