The toxin-antitoxin system of Staphylococcus aureus.

TA系统在细菌中很常见。TA系统有八个家族，它们都在类似的原理下工作，具有稳定的毒素和易受应激诱导的蛋白酶影响的不稳定的抗毒素。在TA对中，MazEF和RelBE系统是研究得最好的。基因组分析显示MazEF和RelBE旁系同源物在许多革兰氏阳性细菌。初步研究表明，S.金黄色葡萄球菌是特异性内切核糖核酸酶，其在VUUV'位点切割，其中V或V'可以是A、C或G。我们推测，这可能是可行的破坏毒素的结合，抗毒素MazE与小的合成化合物释放的毒性MazF，从而代表了一种新的方法，用于开发新的抗菌化合物。我们还检查了MazF对mRNA切割的特异性，发现一些管家和毒力调节mRNA被保留，而其他如hla、spa和sigB则容易被切割。我们怀疑RNA结合蛋白可能保护这些mRNA中的一些。由于我们已经从我们的试点筛选中获得了一些“推定化合物”，因此我们建议在测定中使用新型荧光DNA-RNA杂交底物筛选针对抗MazE的小合成化合物。为了满足上述目标，我们开发了以下目标：I）鉴定保护选择性mRNA（例如选择性管家基因和sarA）免受MazFsa切割的RNA结合蛋白; II）开发筛选干扰MazEsa与MazFsa的功能或结合的小分子的测定。总的来说，这些数据将突出革兰氏阳性菌中TA系统的独特性。作为抗多药耐药沙门氏菌的治疗选择。金黄色葡萄球菌的能力有限，我们的筛选试验将为开发针对金黄色葡萄球菌的新型抗菌治疗提供针对迷宫的初始化合物。金黄色

TA systems are common in bacteria. There are eight families of TA systems all of which operate under a similar principle, with a stable toxin and a labile antitoxin prone to proteases that are induced upon stress. Among the TA pair, the MazEF and RelBE systems are the best studied. Genomic analysis revealed MazEF and RelBE paralogs in many Gram+ bacteria. Preliminary studies indicated that the MazF toxin in S. aureus is a specific endoribonuclease that cuts at a VUUV’ site where V or V’ can be A, C or G. We speculate that it may be feasible to disrupt the binding of the toxin to the antitoxin MazE with small synthetic compounds to unleash the toxicity of MazF, thus representing a new approach for the development of novel antimicrobial compounds. We also examined the specificity of MazF on Mrna cleavage and found that some housekeeping and virulence regulator mRNAs are spared while others such as hla, spa and sigB are easily cleaved. We suspect RNA-binding protein may protect some of these mRNAs. As we already have a few “putative compounds” from our pilot screen, we propose to screen for small synthetic compounds against anti-MazE, using a novel fluorescent DNA-RNA hybrid substrate in the assay. To satisfy the above goal, we have developed the following aims: I) Identification of RNA binding protein(s) that protects selective mRNA (e.g. selective housekeeping gene and sarA) from MazFsa cleavage; II) developing an assay to screen for small molecule(s) that interferes with function or binding of MazEsa to MazFsa. Collectively, these data will highlight the uniqueness of the TA systems in Gram+ bacteria. As therapy options against multidrug resistant S. aureus are limited, our screening assays will provide the initial compounds against MazE for the development of novel antimicrobial therapy against S. aureus