Mutations of putP that alter the lithium sensitivity of Salmonella typhimurium.
Mutations of putP that alter the lithium sensitivity of Salmonella typhimurium.
复制标题
putP 的突变改变了鼠伤寒沙门氏菌的锂敏感性。
DOI：
10.1111/j.1365-2958.1988.tb00086.x
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发表时间：
1988
影响因子：
3.6
通讯作者：
Maloy,SR
中科院分区：
文献类型：
--
作者：
Myers,RS;Maloy,SR
putP基因编码鼠伤寒沙门氏菌中的主要脯氨酸通透酶，该酶将脯氨酸转运与钠电化学梯度偶联。为了确定参与阳离子结合位点的残基，我们已经分离出了在脯氨酸生长过程中赋予对锂抗性的Pmutants。野生型鼠伤寒沙门氏菌可以在补充有NaCl的培养基中以脯氨酸作为唯一碳源生长良好，但当LiCl取代NaCl时生长较差。与生长表型相反，脯氨酸通透酶能够通过Na+/脯氨酸或Li+/脯氨酸同向转运脯氨酸。因此，我们选择了在锂离子存在下在含有脯氨酸作为唯一碳源的培养基上生长良好的突变体。相对于野生型，所有测定的突变体均表现出Li+脯氨酸和Na+/脯氨酸共转运速率降低。每个突变的位置通过缺失作图确定：突变聚集在putP基因的5′和3′末端的两个小的缺失间隔中。这些锂抗性突变的图谱位置与先前分离的底物特异性突变的位置不同。这些结果表明，Lirmutations可能定义的结构域的蛋白质折叠，形成阳离子结合位点的脯氨酸通透酶。
TheputPgene encodes the major proline permease inSalmonella typhimuriumthat couples transport of proline to the sodium electrochemical gradient. To identify residues involved in the cation binding site, we have isolatedputPmutants that confer resistance to lithium during growth on proline. Wild‐type S.typhimuriumcan grow well on proline as the sole carbon source in media supplemented with NaCl, but grows poorly when LiCl is substituted for NaCl. In contrast to the growth phenotype, proline permease is capable of transporting proline via Na+/proline or Li+/proline symport. Therefore, we selected mutants that grow well on media containing proline as the sole carbon source in the presence of lithium ions. All of the mutants assayed exhibit decreased rates of Li+pro‐line and Na+/proline cotransport relative to wild type. The location of each mutation was determined by deletion mapping: the mutations cluster in two small deletion intervals at the 5′ and 3′ termini of theputPgene. The map positions of these lithium resistance mutations are different from the locations of the previously isolated substrate specificity mutations. These results suggest that Lirmutations may define domains of the protein that fold to form the cation binding site of proline permease.