植物细菌天山根瘤菌调控基因mrtR在群体感应中的作用  

ROLE OF REGULATORY GENE mrtR OF PLANT BACTERIUM MESORHIZOBIUM TIANSHANENSE IN QUORUM SENSING

作　　者：赖欣[1] 戴俊[1] 郑会明[1] 钟增涛[1] 朱军[1] 

机构地区：[1]南京农业大学生命科学学院农业部农业环境微生物工程重点开放实验室,南京210095

出　　处：《土壤学报》2008年第4期705-709,共5页Acta Pedologica Sinica

基　　金：国家杰出青年基金项目(30325004);国家自然科学基金项目(30570011);973项目(001CB1089)联合资助

摘　　要：在许多种类的细菌中均发现了luxR/luxI类型的群体感应调控系统,其中luxR是调节基因,对luxI合成自体诱导物(AI,autoinducer)起着正调控作用。通过建库筛选后,测序比对发现天山根瘤菌中存在mrtR/mrtI系统。通过基因敲除和转录水平基因表达对mrtR进行研究,发现mrtR严格调控着mrtI的表达,同时mrtR的表达也受到AI影响,这表明mrtR表达的调控是一种自调控,同时根毛吸附实验显示该基因对根瘤菌与宿主间相互作用密切相关。The ability of rhizobia to symbiotically fix nitrogen from the atmosphere when forming nodules on their host plant roots requires signal transduction pathways. LuxR/LuxI family proteins are a unique quorum-sensing system, found in many bacteria, LuxR is a regulatory protein which regulates LuxI-type proteins in synthesizing autoinducer （AI）. In this study, sequence analysis was conducted finding a LuxI-type synthase gene, mrtI, and a regulatory gene mrtR present in M. tianshanense, which are homologic to the LuxR/LuxI type of protein. Using gene knock-out, mrtR was found regulating the expression of tutti. Furthermore, and using lacZ transcriptional fusion, AHL molecule demonstrating a key role in mrtR expression, which proves that mrtR is auto-regulated. The root hair adherence experiment showed that mrtR affected plant-bacteria interaction. These data show that it is necessary to have MrtR bonded with AHLs for mrtI expression and the gene plays a key role in regulating the quorum sensing system of M. tianshanense.

关 键 词：群体感应 天山根瘤菌 mrtR 自调控 

分 类 号：Q933[生物学—微生物学]