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首页> 外文期刊>Journal of bacteriology >Penicillin-binding protein 2b of Streptococcus pneumoniae in piperacillin-resistant laboratory mutants.
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Penicillin-binding protein 2b of Streptococcus pneumoniae in piperacillin-resistant laboratory mutants.

机译：耐哌拉西林的实验室突变株中的肺炎链球菌青霉素结合蛋白2b。

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摘要

In Streptococcus pneumoniae, alterations in penicillin-binding protein 2b (PBP 2b) that reduce the affinity for penicillin binding are observed during development of beta-lactam resistance. The development of resistance was now studied in three independently obtained piperacillin-resistant laboratory mutants isolated after several selection steps on increasing concentrations of the antibiotic. The mutants differed from the clinical isolates in major aspects: first-level resistance could not be correlated with alterations in the known PBP genes, and the first PBP altered was PBP 2b. The point mutations occurring in the PBP 2b genes were characterized. Each mutant contained one single point mutation in the PBP 2b gene. In one mutant, this resulted in a mutation of Gly-617 to Ala within one of the homology boxes common to all PBPs, and in the other two cases, the same Gly-to-Asp substitution at the end of the penicillin-binding domain had occurred. The sites affected were homologous to those determined previously in the S. pneumoniae PBP 2x of mutants resistant to cefotaxime, indicating that, in both PBPs, similar sites are important for interaction with the respective beta-lactams.
机译：在肺炎链球菌中，β-内酰胺耐药性的发展过程中观察到青霉素结合蛋白2b（PBP 2b）的变化降低了与青霉素结合的亲和力。现在在增加抗生素浓度的几个选择步骤后分离的三个独立获得的对哌拉西林耐药的实验室突变体中研究了耐药性的发展。突变体在主要方面与临床分离株有所不同：一级耐药与已知的PBP基因的改变不相关，而第一个PBP改变的是PBP 2b。表征了在PBP 2b基因中发生的点突变。每个突变体在PBP 2b基因中都包含一个单点突变。在一个突变体中，这导致在所有PBP共有的同源框之一内Gly-617突变为Ala，在另两个情况下，青霉素结合域末端的Gly-Asp取代相同发生了。受影响的位点与先前在头孢噻肟耐药的肺炎链球菌PBP 2x中确定的位点同源，这表明在两个PBP中，相似的位点对于与各自的β-内酰胺相互作用至关重要。

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