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The cloning and physical map of glnBA genes of Rhodobacter sphaeroides

Han Tao, Wu Yongqiang, Song Hongyu

Shanghai Institute of Plant Physiology,The Chinese Academy of Scienese.Shanghai 200032

Abstract

The purple non-suphur photosynthetic bacterium Rhodobacter sphaeroides fixes nitrogen microaerobically or anaerobically when the level of intracellular fixed nirogen is limited.Using the glnA gene of R. capsulata as probe, three positive clones from the gene libray of R.sphaeroides,named pHT3,pHT10 and pH35 were obtained.When they were conjugated into G29(Gln-mutant of R. capsulata),the strains with pHT10 and pHT35 could grow on RCVB minimal medium and restore the activity of glutamine synthetase and nitrogenase of G29.The results showed that the plasmids pHT10 and pH35 included the complete glnA gene of R.sphaeroides.Then two glnA homologous fragments of plasmid pHT10,3.5kb-BamH Ⅰand 2.7 kb-Pst I fragments were subdoned.By restriction analysis and Southern hybhridization,the sites of glnBA genes on the two fragments were found .The results showed that the special structure of glnB and glnA on one cluster maight be related to the characteristics of nitrogen fixation of this kind of bacterumm.

Key words: R. sphaeroides;Glutomine synthetase;Nitrogen fixation;GlnA gene;GlnB gene

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Citing This Article：

Han Tao, Wu Yongqiang, Song Hongyu. The cloning and physical map of glnBA genes of Rhodobacter sphaeroides. Acta Physiol Sin 1996; 48 (2): (in Chinese with English abstract).