Activation of a new proline transport system in Salmonella typhimurium.
Activation of a new proline transport system in Salmonella typhimurium.
复制标题
鼠伤寒沙门氏菌中新脯氨酸转运系统的激活。
DOI：
10.1128/jb.172.6.2940-2945.1990
复制
发表时间：
1990
影响因子：
3.2
通讯作者：
Maloy,S
中科院分区：
文献类型：
--
作者：
Ekena,K;Liao,MK;Maloy,S
脯氨酸摄取可以介导的野生型鼠伤寒沙门氏菌的三种不同的运输系统：一个高亲和力的脯氨酸运输系统编码的putP基因和两个甘氨酸甜菜碱运输系统与低亲和力的脯氨酸编码的proP和proU基因。然而，只有PutP通透酶运输脯氨酸足够好，以允许脯氨酸作为唯一的碳源或氮源的增长。通过选择允许putP突变体在脯氨酸作为唯一氮源上生长的突变，我们分离出似乎激活隐蔽的脯氨酸转运系统的突变体（指定为proZ）。这些突变体增强了脯氨酸和脯氨酸类似物的转运，但不需要任何已知的脯氨酸转运基因的功能。突变定位在S.鼠伤寒连锁图谱脯氨酸转运的proZ突变体竞争性抑制异亮氨酸和亮氨酸，这表明ProZ表型可能是由于不寻常的突变，改变了底物特异性的支链氨基酸转运系统编码的liv基因。
Proline uptake can be mediated by three different transport systems in wild-type Salmonella typhimurium: a high-affinity proline transport system encoded by the putP gene and two glycine-betaine transport systems with a low affinity for proline encoded by the proP and proU genes. However, only the PutP permease transports proline well enough t allow growth on proline as a sole carbon or nitrogen source. By selecting for mutations that allow a putP mutant to grow on proline as a sole nitrogen source, we isolated mutants (designated proZ) that appeared to activate a cryptic proline transport system. These mutants enhanced the transport of proline and proline analogs but did not require the function of any of the known proline transport genes. The mutations mapped between 75 and 77.5 min on the S. typhimurium linkage map. Proline transport by the proZ mutants was competitively inhibited by isoleucine and leucine, which suggests that the ProZ phenotype may be due to unusual mutations that alter the substrate specificity of the branched-chain amino acid transport system encoded by the liv genes.