FemA, a host-mediated factor essential for methicillin resistance in Staphylococcus aureus: Molecular cloning and characterization
FemA, a host-mediated factor essential for methicillin resistance in Staphylococcus aureus: Molecular cloning and characterization
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FemA，金黄色葡萄球菌甲氧西林耐药所必需的宿主介导因子：分子克隆和表征
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发表时间：
1989
期刊：
影响因子：
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通讯作者：
F. Kayser
中科院分区：
文献类型：
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作者：
B. Berger;L. Barberis;A. Strässle;F. Kayser
金黄色葡萄球菌耐甲氧西林决定因子（mec）存在于等基因敏感细胞中不存在的附加DNA上。然而，除了mec外，其他染色体决定因素对甲氧西林耐药性的表达也是必不可少的。我们克隆并鉴定了一个染色体决定的基因，该基因编码一个对金黄色葡萄球菌耐甲氧西林（femA）表达至关重要的因子。femA定位于染色体第18段，遗传上与甲氧西林耐药决定因素（mec）非常遥远。femA产物为表观大小为48 kDa的蛋白。FemA通过插入Ω22003恢复对甲氧西林敏感的金黄色葡萄球菌对甲氧西林的耐药性（FemA::Tn551）。尽管在β-内酰胺类抗生素存在的情况下，FemA是细胞生长所必需的，但它对mec编码的低亲和力、额外的青霉素结合蛋白（PBP2’）的合成没有影响，已知在甲氧西林抑制浓度存在的情况下，该蛋白对细胞壁合成至关重要。核苷酸序列分析、Northern RNA印迹和S1核酸酶RNA定位表明，femA转录在多顺反子mRNA上。该mRNA包含FemA编码区（ORF433）和第二个编码区（ORF419），产生47 kDa的蛋白。FemA的核苷酸和氨基酸序列与ORF419具有同源性，表明这些基因是通过基因复制产生的。此外，我们提出的证据表明，第二染色体因子，femB，参与表达甲氧西林耐药的地图接近femA。
SummaryThe methicillin resistance determinant (mec) in Staphylococcus aureus resides on additional DNA not present in isogenic sensitive cells. However, besides mec, other chromosomally determined factors are essential for expression of methicillin resistance. We cloned and characterized a chromosomally determined gene which encodes a factor essential for the expression of methicillin resistance (femA) in S. aureus. femA mapped in chromosomal segment number 18, genetically very distant from the methicillin resistance determinant (mec). The product of femA was a protein of an apparent size of 48 kDa. FemA restored methicillin resistance in S. aureus that had become sensitive to methicillin by insertion of Ω22003 (femA::Tn551). Although FemA was needed for cell growth in the presence of β-lactam antibiotics, it had no influence on the synthesis of the low affinity, additional penicillin-binding protein (PBP2′) encoded by mec and known to be essential for cell wall synthesis in the presence of inhibitory concentrations of methicillin. Nucleotide sequence analysis, Northern RNA blotting and S1 nuclease RNA mapping suggested that femA was transcribed on a polycistronic mRNA. This mRNA contained the coding region for FemA (ORF433) and a second coding region (ORF419) producing a protein of 47 kDa. The nucleotide and amino acid sequence of FemA showed homologies with ORF419, suggesting that these genes arose by gene duplication. In addition we present evidence for a second chromosomal factor, femB, involved in expression of methicillin resistance which maps close to femA.