MAGNESIUM TRANSPORT IN SALMONELLA-TYPHIMURIUM - THE INFLUENCE OF NEW MUTATIONS CONFERRING CO2+ RESISTANCE ON THE CORA MG2+ TRANSPORT-SYSTEM
MAGNESIUM TRANSPORT IN SALMONELLA-TYPHIMURIUM - THE INFLUENCE OF NEW MUTATIONS CONFERRING CO2+ RESISTANCE ON THE CORA MG2+ TRANSPORT-SYSTEM
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DOI：
10.1111/j.1365-2958.1991.tb01984.x
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发表时间：
1991-11-01
影响因子：
3.6
通讯作者：
MAGUIRE, ME
中科院分区：
文献类型：
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作者：
GIBSON, MM;BAGGA, DA;MAGUIRE, ME
鼠伤寒沙门氏菌的CorA Mg 2+转运系统介导Mg 2+的流入和流出。corA位点的突变（83.5 min）赋予对Co2+的抗性。利用转座子诱变技术，在S.鼠伤寒杆菌染色体在大肠杆菌中，在95分钟时没有获得对应于所报道的corB位点的突变。corB，corC和corD突变赋予的水平之间的野生型和corA mutations.Isogenic菌株的Co2+抗性的中间体构建含有转座子插入突变的组合在每个三个Co2+抗性位点，以评估其对CorA Mg 2+转运系统的影响。Mg-28（2+）或Co-57（2+）和Ni-63（2+）内流的V（max）和K（m）值（由CorA系统转运的Mg 2+的类似物）与野生型值相比变化不到两倍，无论是否存在突变。然而，虽然流出的Mg-28（2+）通过CorA系统减少了三倍，在菌株携带一个或两个突变等位基因之间的corB，corC，或corD，流出被完全废除，无论是corA或corBCD菌株。因此，虽然corA基因产物是必要的，足以介导Mg 2+流入，Mg 2+流出需要存在的野生型等位基因的corB，corC或corD基因座中的至少一个。
The CorA Mg2+ transport system of Salmonella typhimurium mediates both influx and efflux of Mg2+. Mutations at the corA locus (83.5 min) confer resistance to Co2+. Using transposon mutagenesis, three additional Co2+ resistance loci (corB, corC, and corD) were found and mapped to 55, 15, and 3 min, respectively, on the S. typhimurium chromosome. No mutations corresponding to the reported corB locus at 95 min in Escherichia coli were obtained. The corB, corC, and corD mutations confer levels of Co2+ resistance intermediate between those of the wild-type and corA mutations.Isogenic strains were constructed containing combinations of transposon insertion mutations in each of the three Co2+-resistance loci to assess their influence on the CorA Mg2+ transport system. The V(max) and K(m) values for Mg-28(2+) or for Co-57(2+) and Ni-63(2+) influx, analogues of Mg2+ transported by the CorA system, were changed less than twofold compared with the wild-type values, regardless of the mutation(s) present. However, while efflux of Mg-28(2+) through the CorA system was decreased threefold in strains carrying one or two mutant alleles among corB, corC, or corD, efflux was completely abolished in either a corA or a corBCD strain. Thus, although the corA gene product is necessary and sufficient to mediate Mg2+ influx, Mg2+ efflux requires the presence of a wild-type allele of at least one of the corB, corC or corD loci.