乳酸乳球菌质粒pAG712的特性研究

Characterisation of the Lactococcal Plasmid pAG712

乳酸乳球菌质粒pAG712(15.5kb)赋予乳酸乳球菌细胞凝聚表型,它是以θ模式进行复制,复制蛋白与其它以θ模式进行复制的质粒的复制蛋白具有极高的同源性。复制区上的BglII(4.2kb)片段决定质粒可以在乳酸乳球菌中进行复制。在本研究中,将抗生素抗性基因插入到质粒pAG712中,给予它选择性的标记,在研究中发现凝聚基因(aggregationgene)的存在导致了乳酸乳球菌质粒pAG712的分离不稳定性。

The lactococcal plasmid pAG712 （15.5kb） confers an aggregation phenotype on the cells. It replicates by a theta mechanism, the replication protein has homology with other theta replication proteins. A BghI fragment （4.2kb） which spans the location of the replication protein allows replication in Lactococcus. In this study, the pAG712 plasmid has been marked with an antibiotic resistance gene to give a selectable marker. And we have demonstrated that the presence of aggregation gene resulted in the segregational instability ofpAG712 plasmid.