Functional Characterization of the Site Specific Residues in Mutacin 1140

说明(申请人提供)：抗菌素耐药性是世界范围内一个日益令人担忧的问题，而新的抗菌剂产品的数量不多，加剧了这种情况的严重性。许多医学上重要的细菌菌株对临床感染治疗中使用的抗生素产生了越来越多的抗药性。这个问题将随着时间的推移继续恶化，除非很快开发出新的抗生素。变形链球菌生产的一种抗生素--突变素1140的初步表征表明，它有很大的前景。它是一种称为抗生素的新型小抗生素的成员。它在低浓度下对所有已测试的革兰氏阳性细菌具有杀菌作用，包括耐多药金黄色葡萄球菌和粪肠球菌。它对一些革兰氏阴性病原体也有活性。使突变蛋白1140成为抗生素的其他特征之一是，在测试的几种病原体中没有发现自发的抗药性突变。本文描述了一种新的粘附素活性机制，即它与脂类II结合，将脂类II从细菌生长区中剥离出来，将脂类II捕获在一个大的粘附素单体复合体中。这些生长区发生在细胞分裂的部位，在那里脂II携带合成新细胞壁所需的肽聚糖亚基。我们的团队已经解决了突变蛋白1140的三维结构，为定点突变提供了一个“智力选择”的机会。因此，本应用的目标是确定抗生素的结构成分，这些结构成分对于脂类II结合、复合体的形成以及它们与翻译后修饰机制相关的功能是重要的。有趣的是，设计含有脂类II结合能力但已失去形成复合体能力的类似物，以及可形成复合体但已失去与脂类II结合能力的类似物。这些类型的类似物将进一步加深我们对突变体1140的活性机制的理解，因为它与抗生素中的特定区域有关。在这项提案中，每个突变体都将被评分，因为它们与脂类II结合、复合体形成、杀菌活性以及它们与修饰机制相关的功能有关。公共卫生相关性该提案涉及到需要进一步了解一种名为MUTACIN 1140的抗微生物化合物的功能。更好地了解这种抗生素的结构元素的功能可能有助于开发一类新的抗生素。

DESCRIPTION (provided by applicant): Antimicrobial resistance is a growing concern worldwide, and the severity of the situation is compounded by the modest pipeline of new antimicrobial products. Many strains of medically important bacteria have become increasingly resistant to antibiotics used in the treatment of clinical infections. This problem will continue to worsen over time, unless new antibiotics are developed soon. Preliminary characterization of mutacin 1140, an antibiotic made by a strain of Streptococcus mutans, suggests that it holds great promise. It is a member of the small, novel class of antibiotics called lantibiotics. It is bactericidal at low concentrations against all Gram positive bacteria which it has been tested, including multidrug resistant Staphylococcus aureus and Enterococcus faecalis. It is also active against some Gram negative pathogens. Among other features that make mutacin 1140 desirable for use as an antibiotic, is that spontaneous mutations to resistance have not been found among several pathogens tested. A novel mechanism of activity for mutacin has been described, in which it binds to lipid II trapping lipid II in a large complex of mutacin monomers that abduct lipid II from bacterial growth zones. These growth zones occur at the site of cell division where lipid II carries the peptidoglycan subunits required for the synthesis of new cell wall. The three dimensional structure of mutacin 1140 has been solved by our group providing an opportunity to make "intellectual choices" for site-directed mutagenesis. Thus the goal of this application is to identify the structural components of the antibiotic that are important for lipid II binding, complex formation, and their associated functions with the post-translational modification machinery. Of interest, would be the design of analogs that contain lipid II binding capability, but have lost the ability to form complexes, as well as analogs that can form complexes, but have lost the ability to bind to lipid II. These types of analogs would further our understanding of the mechanism of activity of mutacin 1140 as it pertains to specific regions in the antibiotic. Each mutant will be scored in this proposal, as they relate to lipid II binding, complex formation, bactericidal activity, and their associated function with the modification machinery. PUBLIC HEALTH RELEVANCE The proposal addresses the need for furthering our understanding of the function of an antimicrobial compound called mutacin 1140. A better understanding of the function of the structural elements of this antibiotic may aid in the development of a new class of antibiotics.