乳酸链球菌nisk基因与细菌性双成分调节子的研究

THE STUDY ON NISK GENE AND BACTERIAL DOUBLE-COMPONENT REGULATORS IN LACTOCOCCUs LACTIS

本研究通过对乳酸链球菌亚种Ｎ８的Ｎｉｓｉｎｚ结构基因下游部分基因区的分子克隆、序列分析和ＯＲＦ的检测，揭示出一个属于细菌性双成份调节于系统的基因，ｎｉＳＫ，其起始区略与ｎｉｓＲ末端重叠，并发现ｎｉｓＲ和ｎｉｓｋ同被转录一个多顺反子ｍＲＮＡ。在ｎｉｓＫ编码区后，有一个ρ非依赖性终止子（Ｇ°＝－４．７Ｋａｌ／ｍｏｌ）。推导出的含４４７个氮基酸的ｎｉｓｋ蛋白在其Ｎ末端区有两个过膜序列。其Ｃ末端区与细菌性双成份调节子系统的若干组氦酸激酶Ｃ末端同源。

In this study,partial area downstream from tbe structural gene ofNisin Z in the strain lactococcus lactis subsp,lactis N8 was cloned andsequenced.EYamination of open reading frames revealed a gene, Nisk,which is belnog to bacteial double-component system of regulators,Thegene start slightly overlaps theend of NisR. These two genes are co-transcribed to a polycistronic mRNA,in which aLputative p-independentterminator(△℃=-4.7 kcal/mol)follows the coding region of NisK. The deduced 447 amino acid NisK protein has two transmembrane sequ-ences in N-terminal domain,The C-terminal hydrophilic domain ishomologous to the C-terminal of several histidine kinases of bacterialtwo-component regulator systems.