The induction of Sinorhizobium meliloti C4-dicarboxylate transport system （Dct） is regulated by oxygen concentration

作     者：WEN Jin1, NAN Beiyan1, Fergal O’Gara2 & WANG Yiping1 1. National Laboratory of Protein Engineering and Plant Genetic Engi-neering, College of Life Sciences, Peking University, Beijing 100871, China 2. Microbiology Department, University College Cork, National Univer-sity Ireland, Cork, Ireland 

出 版 物：《Science Bulletin》 (科学通报(英文版))

年 卷 期：2005年第17期

页      面：77-81页

学科分类：081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 070303[理学-有机化学] 0703[理学-化学] 

主　　题：Sinorhizobium meliloti Dct system oxygen concentration. 

摘      要：The Sinorhizobium meliloti C4-dicarboxylate transport (Dct) system is essential for symbiotic nitrogen fixation. The dctA gene, encoding the C4-dicarboxylate per-mease, is expressed in both free living and symbiotic cells. But in free living cells expression of dctD and dctB is abso-lutely required for the expression of dctA. In this study, in order to investigate the effect of oxygen concentration on the induction of Dct system, E. coli DH5α strain which carries the plasmid-encoded dctABD operon was used in tube assays. It was found that the specific induction of Dct system oc-curred only at a certain depth under the surface of M63- 0.6% agar media, suggesting that Dct system could respond to oxygen concentration during succinate-induced expression. Furthermore, when measured at different oxygen concentra-tions, the highest expression level was observed at oxygen concentration of 2%. Thus, we predict that in addition to dicarboxylates, the induction of Dct system may also regu-lated by oxygen concentration.