温度对假单胞菌rsmA突变株M-18R合成Plt和PCA的区别性影响  

Differential Effect of Temperature on Plt and PCA Synthesis in A rsmA Inactivated Mutant Strain of Pseudomonas sp . M-18

作　　者：王震[1] 何幸[1] 王素莲[1] 张雪洪[1] 许煜泉[1] 

机构地区：[1]上海交通大学生命科学技术学院，上海200240

出　　处：《生物工程学报》2005年第1期118-122,共5页Chinese Journal of Biotechnology

基　　金：上海交通大学PRP项目 (No .0 80 411);唐氏基金资助。~~

摘　　要：次生代谢物阻遏蛋白 (Repressorofsecondarymetabolite ,Rsm)A是一种全局性调控因子 ,与mRNA的RBS结合 ,转录后水平上抑制基因翻译。运用同源重组技术 ,构建了假单胞菌 (Pseudomonassp .)M_18的rsmA突变菌株M_18R。在 37℃、2 8℃恒温和短期升温 (37℃、4h培养 ,转 2 8℃继续培养 )条件下 ,比较野生株M_18和突变株M_18R生物合成藤黄绿菌素 (Plt)和吩嗪_1_羧酸 (PCA)的量。在 37℃条件下 ,M_18和M_18R合成这两种抗生物质的能力几乎受到完全抑制。在 2 8℃条件下 ,M_18R合成Plt的量约为野生型M_18的 10倍 ,达到 2 70 μg mL ,但是合成PCA的量仅为野生型的 5 0 %。经短期升温培养 ,M_18的Plt合成量明显下降 ,PCA产量降低不显著 ;相反 ,M_18R合成Plt的量达到 4 0 0 μg mL ,但PCA产量的变化仍不明显。推测 ,M_18菌株细胞内存在着某种与RsmA相关联的温度敏感因子 ,在RsmA缺失条件下 ,作为专一性激活剂促进Plt的生物合成 ,但是 ,并不参与对PCA合成的调控。Rsm (repressor of secondary metabolite) A is an mRNA binding protein which functions as a global repressor to control multiple genes at the posttranscriptional level. Using homologous recombination technique a chromosomal rsmA inactivated mutant strain M_18R was constructed in Pseudomonas sp . M_18, a strain of plant_growth_promoting rhizobacteria, which could inhibit several soilborn phytopathogens by producing secondary metabolites including phenazine_1_carboxylic acid(PCA)and pyoluteorin (Plt) in one single strain. To further study the effect of RsmA on the synthesis of Plt and PCA in the wild type strain M_18, the dynamic curves of Plt and PCA produced respectively by M_18 and M_18R were measured in KMB medium under different temperature conditions such as 37℃ constant, 28℃ constant and nonconstant(37℃ 4 hours at first and then 28℃ constant)cultivation. The synthesis of both Plt and PCA were almost inhibited in the cultures under the condition of 37℃. At 28℃, however, compared with the wild type strain M_18, the mutant strain produced tenfold amount of Plt, while the production of PCA decreased only about 50%. When cultivated under the nonconstant condition, the amount of Plt produced by M_18R could reach 400 μg/mL while the PCA production was not significantly affected, but in the wild type strain M_18, the amount of Plt production decreased obviously while the PCA production was not affected in comparison with the results at 28℃ constant. These results suggest that a temperature sensitive factor exists to function as an activator independent of RsmA to promote the synthesis of Plt in the rsmA mutant strain M_18R while it may bind with RsmA to repress the synthesis of Plt in the wild type strain M_18 But this factor did not exert any affect on the synthesis of PCA.

关 键 词：假单胞菌M-18 RSMA 吩嗪-1-羧酸 藤黄绿菌素 温度 

分 类 号：TQ92[轻工技术与工程—发酵工程]