A functional myo-inositol catabolism pathway is essential for rhizopine utilization by Sinorhizobium meliloti
A functional myo-inositol catabolism pathway is essential for rhizopine utilization by Sinorhizobium meliloti
复制标题
DOI：
10.1099/00221287-144-10-2915
复制
发表时间：
1998-10-01
期刊：
影响因子：
2.8
通讯作者：
Rossbach, S
中科院分区：
文献类型：
--
作者：
Galbraith, MP;Feng, SF;Rossbach, S
Rhizopine（L-3-O-methyl-scyllo-inosamine）是苜蓿根瘤菌（Sinorhizobium meliloti）诱导产生的一种共生特异性化合物。据推测，根瘤菌菌株能够合成和分解代谢根碱获得竞争优势，在根际。本文分析了Rhizopine的降解途径。由于Rhizopine是肌醇衍生物，因此测试肌醇催化剂是否参与Rhizopine利用。克隆了一个以肌醇为唯一碳源进行酶解所需的基因位点。苜蓿草。通过转座子Tn 5诱变确定了该基因座，并测定了其DNA序列。基于DNA相似性研究和酶分析，该基因区域被证明编码一个S。草木犀肌醇脱氢酶。在肌醇脱氢酶基因（idhA）中携带突变的菌株不显示肌醇脱氢酶活性，不能利用肌醇作为唯一的碳/能源，并且不能分解代谢Rhizopine。因此，肌醇脱氢酶活性对S.苜蓿草。
Rhizopine (L-3-O-methyl-scyllo-inosamine) is a symbiosis-specific compound found in alfalfa nodules induced by specific Sinorhizobium meliloti strains. It has been postulated that rhizobial strains able to synthesize and catabolize rhizopine gain a competitive advantage in the rhizosphere. The pathway of rhizopine degradation is analysed here. Since rhizopine is an inositol derivative, it was tested whether inositol catabolism is involved in rhizopine utilization. A genetic locus required for the catabolism of inositol as sole carbon source was cloned from S. meliloti. This locus was delimited by transposon Tn5 mutagenesis and its DNA sequence was determined. Based on DNA similarity studies and enzyme assays, this genetic region was shown to encode an S. meliloti myo-inositol dehydrogenase. Strains that harboured a mutation in the myo-inositol dehydrogenase gene (idhA) did not display myoinositol dehydrogenase activity, were unable to utilize myo-inositol as sole carbon/energy source, and were unable to catabolize rhizopine. Thus, myoinositol dehydrogenase activity is essential for rhizopine utilization in S. meliloti.