Reconstruction of the Phenotypes of Methicillin-Resistant Staphylococcus aureus by Replacement of the Staphylococcal Cassette Chromosome mec with a Plasmid-Borne Copy of Staphylococcus sciuri pbpD Gene
Reconstruction of the Phenotypes of Methicillin-Resistant Staphylococcus aureus by Replacement of the Staphylococcal Cassette Chromosome mec with a Plasmid-Borne Copy of Staphylococcus sciuri pbpD Gene
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DOI：
10.1128/aac.01099-08
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发表时间：
2009-02-01
影响因子：
4.9
通讯作者：
Tomasz, Alexander
中科院分区：
文献类型：
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作者：
Antignac, Aude;Tomasz, Alexander
mecA 基因是耐甲氧西林金黄色葡萄球菌 (MRSA) 的核心决定因子，它不是该细菌物种的原生基因，但可能起源于动物共生物种松鼠葡萄球菌。所有松鼠链球菌菌株均携带 pbpD 形式的 mecA 密切同源物，pbpD 是松鼠链球菌青霉素结合蛋白 4 (PBP 4) 的遗传决定因子。在这里，我们描述了一个实验系统，可用于对该命题进行额外的测试。将松鼠链球菌pbpD基因克隆到穿梭质粒中，并导入甲氧西林敏感的金黄色葡萄球菌菌株COL-S，该菌株衍生自亲本MRSA菌株COL，从亲本MRSA菌株COL中切除了抗性盒葡萄球菌盒染色体mec。 Sciuri pbpD 决定簇在金黄色葡萄球菌转导子中转录和翻译，产生大量 84-kDa Sciuri PBP 4，然后沉积在宿主细菌的质膜中。携带异源松鼠链球菌pbpD基因的转导子表现出亲本MRSA菌株COL的典型特性，包括对结构不同的β-内酰胺的广谱、高水平和同质抗性。抗生素耐药性依赖于金黄色葡萄球菌 PBP 2 的功能，并受到特定调节基因 mecI 和 mecR 以及细胞壁生物合成早期步骤抑制剂的抑制。松鼠链球菌 PBP 4 还能够取代金黄色葡萄球菌天然 PBP 2 的基本生理功能，并产生亲本 MRSA 菌株 COL 的典型肽聚糖。我们的结果进一步支持了以下观点：MRSA 菌株的耐药决定簇 mecA 是从 Sciuri pbpD 进化而来的。
The mecA gene, the central determinant of methicillin (meticillin)-resistant Staphylococcus aureus (MRSA), is not native to this bacterial species but may have originated in the animal commensal species Staphylococcus sciuri. All S. sciuri strains carry a close homologue of mecA in the form of pbpD, the genetic determinant of penicillin binding protein 4 (PBP 4) of S. sciuri. Here we describe an experimental system that could be used for additional tests for this proposition. The S. sciuri pbpD gene was cloned into a shuttle plasmid and introduced into methicillin-susceptible S. aureus strain COL-S derived from parental MRSA strain COL from which the resistance cassette staphylococcal cassette chromosome mec was excised. The S. sciuri pbpD determinant was transcribed and translated in the S. aureus transductants producing large amounts of the 84-kDa S. sciuri PBP 4 and was then deposited in the plasma membrane of the host bacterium. Transductants carrying the heterologous S. sciuri pbpD gene exhibited properties typical of those of parental MRSA strain COL, including broad-spectrum, high-level, and homogeneous resistance to structurally different beta-lactams. Antibiotic resistance was dependent on the functioning of S. aureus PBP 2 and was suppressed by the specific regulatory genes mecI and mecR and by inhibitors of an early step in cell wall biosynthesis. S. sciuri PBP 4 was also able to replace the essential physiological function(s) of the native PBP 2 of S. aureus and produce peptidoglycan typical of that of parental MRSA strain COL. Our results provide further support for the proposition that the resistance determinant mecA of MRSA strains has evolved from S. sciuri pbpD.