Molecular analysis of fusidic acid resistance in Staphylococcus aureus
Molecular analysis of fusidic acid resistance in Staphylococcus aureus
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DOI：
10.1046/j.1365-2958.2003.03307.x
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发表时间：
2003-01-01
影响因子：
3.6
通讯作者：
Wichelhaus, TA
中科院分区：
文献类型：
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作者：
Besier, S;Ludwig, A;Wichelhaus, TA
夫西地酸是一种针对严重革兰氏阳性感染的强效抗生素，可干扰延伸因子 G (EF-G) 的功能，从而抑制细菌蛋白质的合成。在这项研究中，我们证明金黄色葡萄球菌中的夫西地酸耐药性是由编码 EF-G 的染色体 fusA 基因内的点突变引起的。 FusA 的序列分析揭示了突变变化，导致 10 种耐夫西地酸临床金黄色葡萄球菌菌株以及在体外在夫西地酸选择压力下分离的 10 种耐夫西地酸金黄色葡萄球菌突变体中发生氨基酸取代。鉴定出 14 个不同的氨基酸交换，仅限于 EF-G 内的 13 个氨基酸残基。为了证实在 EF-G 中观察到的氨基酸交换对于金黄色葡萄球菌中夫西地酸抗性的产生的重要性，通过定点诱变构建了编码具有 P406L、H457Y 和 L461 K 交换的 EF-G 衍生物的三个突变体 fusA 等位基因。在每种情况下，将质粒上的突变体fusA等位基因引入夫西地酸敏感的金黄色葡萄球菌菌株RN4220中引起夫西地酸抗性表型。对重组细菌测定的夫西地酸升高的最低抑制浓度与对夫西地酸抗性临床金黄色葡萄球菌分离株和含有相同染色体突变的体外突变体观察到的浓度类似。因此，所提供的数据提供了证据，证明 EF-G 内的单个氨基酸交换对于金黄色葡萄球菌中夫西地酸抗性的产生至关重要。
Fusidic acid is a potent antibiotic against severe Gram-positive infections that interferes with the function of elongation factor G (EF-G), thereby leading to the inhibition of bacterial protein synthesis. In this study, we demonstrate that fusidic acid resistance in Staphylococcus aureus results from point mutations within the chromosomal fusA gene encoding EF-G. Sequence analysis of fusA revealed mutational changes that,cause amino acid substitutions in 10 fusidic acid-resistant clinical S. aureus strains as well as in 10 fusidic acid-resistant S. aureus mutants isolated under fusidic acid selective pressure in vitro. Fourteen different amino acid exchanges were identified that were restricted to 13 amino acid residues within EF-G. To confirm the importance of observed amino acid exchanges in EF-G for the generation of fusidic acid resistance in S. aureus, three mutant fusA alleles encoding EF-G derivatives with the exchanges P406L, H457Y and L461 K were constructed by site-directed mutagenesis. In each case, introduction of the mutant fusA alleles on plasmids into the fusidic acid-susceptible S. aureus strain RN4220 caused a fusidic acid-resistant phenotype. The elevated minimal inhibitory concentrations of fusidic acid determined for the recombinant bacteria were analogous to those observed for the fusidic acid-resistant clinical S. aureus isolates and the in vitro mutants containing the same chromosomal mutations. Thus, the data presented provide evidence for the crucial importance of individual amino acid exchanges within EF-G for the generation of fusidic acid resistance in S. aureus.