浑球红细菌（R．srhaeroides）glnBA基因克隆及其物理图谱  

The Cloning and Physical Map of glnBA Genes of Rhodobacter sphaeroides

作　　者：韩涛 吴永强[1] 宋鸿遇[1] 

机构地区：[1]中国科学院上海植物生理研究所

出　　处：《植物生理学报（0257-4829)》1996年第2期177-183,共7页Acta Phytophysiologica Sinica

摘　　要：从浑球红细菌的基因文库中筛选到ｐＨＴ３、ｐＨＴ１０及ｐＨＴ３５三个阳性克隆，其中质粒ｐＨＴ１０与ｐＨＴ３５能遗传互补英膜红细菌的谷氨酰胺缺陷型Ｇ２９，使其ＧＳ酶及固氮酶活性得到恢复。对质粒ｐＨＴ１０上的ｇｌｎＡ同源片段进行了亚克隆和限制性内切酶图谱分析，确定了浑球红细菌ｇｌｎＢ与ｇｌｎＡ之间存在连锁关系。The purple non-sulphur photosynthetic bacterium Rhodobacter sphaeroides fixes nitrogen microaerobically oranaerobically when the level of intracellular fixed nitrogen is limited. Glutamine synthetase (GS: EC 6. 3. 1. 2 )plays a key role in nitrogen assimilation. In enteric bacteria, the glnA gene isa member of the glnAntrBC operon and iscontrolled by a complex nitrogenregulatory system (ntr ) that coordinatelyregulates a number of genes involved innitrogen metabolism. In other bacteria,such as Rhodobacter capsulata, ,the glnA is amember of the glnBA operon and is regulated in a manner fundamentally different from that in the Enterobacteriaceae.Using the glnA gene of R. capsulata asprobe, we got three positive clones fromthe gene library of R. spieroides, namedpHT3, pHT10 and pHT35. When theywere conjugated into G29 (Gln- mutantof R. capsulata), the strains with PHT10and pHT35 could grow on RCVB minimal medium and restore the activity ofglutumine synthetase and nitrogenase ofG29 (Table 2). The results showed thatthe plasmids pHT10 and pHT35 included the complete glnA gene of R.sphaeroides. Then we subeloned two glnAhomologous fragments of plasmidpHT10, 3. 5 kb-BamH I and 2. 7 kb-PstI fragments. By restriction analysisand Southern hybridization,we locatedthe sites of glnBA genes on the two fragments (Fig. 3). The results showed thatthe special structure of glnB and glnA onone cluster maight be related to thecharacteristics of nitrogen fixation ofthis kind of bacterium.

关 键 词：浑球红细菌 光合细菌 基因克隆 物理图谱 

分 类 号：Q939.105[生物学—微生物学]