GENETIC-CHARACTERIZATION OF A HIGHLY EFFICIENT ALTERNATE PATHWAY OF SERINE BIOSYNTHESIS IN ESCHERICHIA-COLI
GENETIC-CHARACTERIZATION OF A HIGHLY EFFICIENT ALTERNATE PATHWAY OF SERINE BIOSYNTHESIS IN ESCHERICHIA-COLI
复制标题
DOI：
10.1128/jb.169.6.2611-2617.1987
复制
发表时间：
1987-06-01
影响因子：
3.2
通讯作者：
SOMERVILLE, RL
中科院分区：
文献类型：
--
作者：
RAVNIKAR, PD;SOMERVILLE, RL
在大肠杆菌中存在一组已知的酶，它们被证明以一种有效和协调的方式将苏氨酸转化为丝氨酸。由这些酶催化的反应序列被称为图腾循环(苏氨酸利用)。为了证明相关基因及其蛋白产物在丝氨酸生物合成中起重要作用，对一些突变体进行了分析。在血清、Serb、SERC或GlyA中有病变的大肠杆菌菌株在添加高水平的亮氨酸、精氨酸、赖氨酸、苏氨酸和蛋氨酸的最低限度的培养基上很容易生长。用已知的Ser基因中的一个损伤加上GlyA(丝氨酸羟甲基转移酶)、GCV(甘氨酸裂解系统)或TdH(苏氨酸脱氢酶)的第二个损伤的双重突变体在该培养基上没有观察到生长。分离到了能够在未添加微量或添加低水平亮氨酸、精氨酸、赖氨酸、苏氨酸和蛋氨酸的基础上生长的SERs突变体的假逆转株。至少有两个非连锁突变与这些表型相关。
There exists in Escherichia coli a known set of enzymes that were shown to function in an efficient and concerted way to convert threonine to serine. The sequence of reactions catalyzed by these enzymes is designated the Tut cycle (threonine utilization). To demonstrate that the relevant genes and their protein products play essential roles in serine biosynthesis, a number of mutants were analyzed. Strains of E. coli with lesions in serA, serB, serC, or glyA grew readily on minimal medium supplemented with elevated levels of leucine, arginine, lysine, threonine, and methionine. No growth on this medium was observed upon testing double mutants with lesions in one of the known ser genes plus a second lesion in glyA (serine hydroxymethyltransferase), gcv (the glycine cleavage system), or tdh (threonine dehydrogenase). Pseudorevertants of ser mutants capable of growth on either unsupplemented minimal medium or medium supplemented with low levels of leucine, arginine, lysine, threonine, and methionine were isolated. At least two unlinked mutations were associated with such phenotypes.