Characterization of a mutationally altered dihydropteroate synthase contributing to sulfathiazole resistance in Escherichia coli.
Characterization of a mutationally altered dihydropteroate synthase contributing to sulfathiazole resistance in Escherichia coli.
复制标题
导致大肠杆菌中磺胺噻唑耐药的突变二氢叶酸合酶的表征。
DOI：
10.1089/mdr.1998.4.91
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Nichols,BP
中科院分区：
文献类型：
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作者：
Vedantam,G;Nichols,BP
筛选出一系列对磺胺噻唑耐药的大肠杆菌菌株。耐药发生在7个增量，表明积累了几个突变，有助于整体磺胺噻唑耐药。所有的耐药菌株都有一个磺胺噻唑耐药二氢蝶酸合酶与Pro到Ser取代的氨基酸位置64。野生型酶的过度生产没有导致磺胺噻唑抗性，然而突变酶的过度生产导致显著的抗性。相反，过量生产的野生型酶在磺胺噻唑耐药的背景下，导致电阻下降。虽然DHPS在粗提物中的比活性与野生型没有显着差异，但氨基酸取代导致酶的Km为对氨基苯甲酸酯增加10倍，Ki为磺胺噻唑增加100倍。
A series ofEscherichia colistrains were selected for increasing resistance to sulfathiazole. Resistance occurred in seven increments, suggesting the accumulation of several mutations that contributed to overall sulfathiazole resistance. All of the resistant strains had a sulfathiazole-resistant dihydropteroate synthase with a Pro to Ser substitution at amino acid position 64. Overproduction of the wild-type enzyme did not result in sulfathiazole resistance, however overproduction of the mutant enzyme resulted in significant resistance. Conversely, overproduction of the wild-type enzyme in a sulfathiazole-resistant background resulted in a decrease in resistance. Although the specific activity of DHPS in crude extracts was not significantly different from the wild type, the amino acid substitution resulted in an enzyme with a tenfold increase in the Km forp-aminobenzoate, and a 100-fold increase in the Ki for sulfathiazole.