Functional Characterization of the Site Specific Residues in Mutacin 1140

描述（由申请人提供）：抗菌药物耐药性是全球日益关注的问题，新抗菌产品的适度管道加剧了情况的严重性。许多医学上重要的细菌菌株对用于治疗临床感染的抗生素的耐药性越来越强。随着时间的推移，这个问题将继续恶化，除非很快开发出新的抗生素。变形链球菌1140是一种由变形链球菌菌株制成的抗生素，其初步特性表明它具有很大的前景。它是一个小的，新的抗生素类称为lantibiotics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，包括多重耐药金黄色葡萄球菌和粪肠球菌。它还对一些革兰氏阴性病原体具有活性。在使突变蛋白1140理想地用作抗生素的其他特征中，在测试的几种病原体中尚未发现对抗性的自发突变。已经描述了一种新的突变蛋白活性机制，其中它与脂质II结合，将脂质II捕获在突变蛋白单体的大复合物中，所述突变蛋白单体从细菌生长区绑架脂质II。这些生长区出现在细胞分裂的位点，在那里脂质II携带合成新细胞壁所需的肽聚糖亚基。我们的小组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，本申请的目的是鉴定对脂质II结合、复合物形成及其与翻译后修饰机制相关功能重要的抗生素结构组分。感兴趣的是设计含有脂质II结合能力但失去形成复合物的能力的类似物，以及可以形成复合物但失去结合脂质II的能力的类似物。这些类型的类似物将使我们进一步理解突变蛋白1140的活性机制，因为它涉及抗生素中的特定区域。每个突变体将在本提案中进行评分，因为它们与脂质II结合、复合物形成、杀菌活性及其与修饰机制的相关功能有关。公共卫生相关性该提案提出了进一步了解一种名为mutacin 1140的抗菌化合物功能的必要性。更好地了解这种抗生素的结构元件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.