Insights into the genome of the enteric bacterium Escherichia blattae:: Cobalamin (B12) biosynthesis, B12-dependent reactions, and inactivation of the gene region encoding B12-dependent glycerol dehydratase by a new Mu-like prophage
Insights into the genome of the enteric bacterium Escherichia blattae:: Cobalamin (B12) biosynthesis, B12-dependent reactions, and inactivation of the gene region encoding B12-dependent glycerol dehydratase by a new Mu-like prophage
复制标题
DOI：
10.1159/000085788
复制
发表时间：
2004-01-01
影响因子：
1.2
通讯作者：
Daniel, R
中科院分区：
文献类型：
--
作者：
Andres, S;Wiezer, A;Daniel, R
已经分析了肠道细菌芽孢杆菌是否存在钴胺素（B-12）生物合成和B-12依赖途径。生化研究表明，芽孢杆菌可通过好氧和厌氧方式重新合成B-12。blattae E. DSM 4481基因组中存在与enterica serovar Typhimurium所有基因具有高度相似性的基因，这些基因参与B-12生物合成的氧不依赖途径。dha调控子编码甘油厌氧转化为1,3-丙二醇的关键酶，包括辅酶b -12依赖的甘油脱水酶。小蠊DSM 4481缺乏甘油脱水酶活性，在甘油作用下无厌氧生长，但其基因组中含有dha调控子。棘球绦虫的dha调控是不寻常的，因为它含有两种二羟丙酮激酶的基因。与其他肠道细菌的dha调控的主要区别是通过插入一个33,339 bp的前噬菌体（MuEb）使脱水酶编码基因区域失活。序列分析显示MuEb属于噬菌体Mu家族。株ATCC 33429和ATCC 33430不含MuEb。因此，这两种菌株都含有一个完整的脱水酶编码基因区域和发酵甘油。这两株菌株的甘油脱水酶和相关基因（dhaBCE）的性质与其他b -12依赖的甘油和二醇脱水酶相似，但这两种脱水酶对甘油的亲和力是迄今所鉴定的所有b -12依赖的脱水酶中最高的。除了编码b -12依赖性甘油脱水酶的非功能基因外，bladee . DSM 4481基因组中只含有另一种b -12依赖性酶的基因，即甲基钴胺依赖性蛋氨酸合成酶。版权所有(C) 2004 S. Karger AG，巴塞尔。
The enteric bacterium Escherichia blattae has been analyzed for the presence of cobalamin (B-12) biosynthesis and B-12-dependent pathways. Biochemical studies revealed that E blattae synthesizes B-12 de novo aerobically and anaerobically. Genes exhibiting high similarity to all genes of Salmonella enterica serovar Typhimurium, which are involved in the oxygen-independent route of B-12 biosynthesis, were present in the genome of E. blattae DSM 4481. The dha regulon encodes the key enzymes for the anaerobic conversion of glycerol to 1,3-propanediol, including coenzyme B-12-dependent glycerol dehydratase. E. blattae DSM 4481 lacked glycerol dehydratase activity and showed no anaerobic growth with glycerol, but the genome of E. blattae DSM 4481 contained a dha regulon. The E. blattae dha regulon is unusual, since it harbors genes for two types of dihydroxyacetone kinases. The major difference to dha regulons of other enteric bacteria is the inactivation of the dehydratase-encoding gene region by insertion of a 33,339-bp prophage (MuEb). Sequence analysis revealed that MuEb belongs to the Mu family of bacteriophages. The E. blattae strains ATCC 33429 and ATCC 33430 did not contain MuEb. Accordingly, both strains harbored an intact dehydratase-encoding gene region and fermented glycerol. The properties of the glycerol dehydratases and the correlating genes (dhaBCE) of both strains were similar to other B-12-dependent glycerol and diol dehydratases, but both dehydratases exhibited the highest affinity for glycerol of all B-12-dependent dehydratases characterized so far. In addition to the non-functional genes encoding B-12-dependent glycerol dehydratase, the genome of E. blattae DSM 4481 contained the genes for only one other B-12-dependent enzyme, the methylcobalamin-dependent methionine synthase. Copyright (C) 2004 S. Karger AG, Basel.