mprF基因内多个单核苷酸多态性对金黄色葡萄球菌达托霉素耐药性的影响
Impact of Multiple Single-Nucleotide Polymorphisms Within mprF on Daptomycin Resistance in Staphylococcus aureus.
作者信息
Yang Soo-Jin, Mishra Nagendra N, Kang Kyoung-Mi, Lee Gi-Yong, Park Jong-Hwan, Bayer Arnold S
机构信息
1 Department of Animal Science and Technology, Chung-Ang University , Anseong-si, Republic of Korea.
2 Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center , Torrance, California.
出版信息
Microb Drug Resist. 2018 Oct;24(8):1075-1081. doi: 10.1089/mdr.2017.0156. Epub 2018 Jan 30.
A number of single nucleotide polymorphisms (SNPs) within the mprF open reading frame (ORF) have been associated with daptomycin-resistance (DAP-R) in Staphylococcus aureus. Such SNPs have been found throughout the mprF ORF, although there are clearly preferred "hot spots" within this gene frequently linked to DAP-R phenotype. These mprF SNPs are often correlated with a gain-in-function phenotype, either in terms of increased production (synthase activity) and/or enhanced translocation (translocase activity) of lysyl-phosphatidylglycerol (L-PG) within its cell membrane. However, it is unclear if multiple hot spot mprF SNPs can accumulate within mprF ORFs and cause additive elevations of DAP minimum inhibitory concentrations (MICs). In this study, we used a previously well-characterized plasmid complementation system in S. aureus Newman ΔmprF mutant to express: (1) single point-mutated forms of mprF ORFs cloned from two DAP-R S. aureus strains (mprF or mprF) and (2) dual point-mutated forms of mprF ORFs simultaneously harboring SNPs in the central bifunctional domain and synthase domain in MprF, respectively (mprF or mprF). The current study revealed that, although individual hot spot point mutations within mprF ORF can recapitulate signature DAP-R-associated phenotypes (i.e., increased DAP MICs, enhanced surface positive charge, and increased L-PG synthesis), accumulation of such hot spot point mutations paradoxically caused reduction in these latter three metrics.
金黄色葡萄球菌中,多聚磷酸核糖基转移酶F(mprF)开放阅读框(ORF)内的一些单核苷酸多态性(SNP)与达托霉素耐药性(DAP-R)相关。尽管在该基因内明显存在与DAP-R表型频繁相关的优选“热点”,但在整个mprF ORF中都发现了此类SNP。这些mprF SNP通常与功能获得型表型相关,无论是就其细胞膜内赖氨酰磷脂酰甘油(L-PG)产量增加(合酶活性)和/或转运增强(转位酶活性)而言。然而,尚不清楚多个热点mprF SNP是否会在mprF ORF内累积并导致达托霉素最低抑菌浓度(MIC)的累加升高。在本研究中,我们在金黄色葡萄球菌Newman ΔmprF突变体中使用了先前充分表征的质粒互补系统来表达:(1)从两株DAP-R金黄色葡萄球菌菌株克隆的mprF ORF的单点突变形式(mprF 或mprF),以及(2)mprF ORF的双点突变形式,分别在MprF的中央双功能结构域和合酶结构域中同时含有SNP(mprF 或mprF)。当前研究表明,尽管mprF ORF内的单个热点点突变可重现与DAP-R相关的标志性表型(即,达托霉素MIC增加、表面正电荷增强和L-PG合成增加),但这些热点点突变的累积却反常地导致了后三项指标的降低。