Principles of Protein Mimicry of DNA

描述（由申请人提供）：这一新提案的修订申请描述了对最近发现的五肽重复蛋白（PRP）蛋白质家族成员的“DNA模拟”的全面生物化学和生物物理学研究。来自结核分枝杆菌的MfpA PRP的原子分辨率结构揭示了一种新的蛋白质折叠; MfpA的右手2-螺旋线圈产生一种伸长的结构，该结构是DNA的大小、形状和静电表面的显著模仿。DNA模拟对于MfpA的生物学作用是重要的，这通过其通过结合DNA促旋酶从而抑制其功能而赋予对氟喹诺酮类的抗性的能力来表明。我们将测试的假设，MfpA的物理特性DNA的模仿是其赋予耐药性的能力的核心。我们的长期目标是了解MfpA和其他PRP介导抗生素耐药性的分子机制，并可能调节DNA的酶促加工。MfpA将被开发为探索这种新发现的广泛分布的蛋白质类的DNA模拟的模型系统。氟喹诺酮类抗生素是非常重要的抗生素，因为它们对革兰氏阳性菌、革兰氏阴性菌和分枝杆菌有效。氟喹诺酮类药物以独特的作用机制作用于DNA促旋酶。他们是显着的无毒性和治疗指数是目前所有处方抗生素中最高的。由于质粒编码的蛋白质的表达而导致的可传播形式的氟喹诺酮耐药性的快速出现和传播威胁到这些抗生素的临床效用。拟议的研究旨在了解肽重复蛋白MfpA和Qnr的物理性质如何产生对氟喹诺酮类药物的耐药性。这种理解将为氟喹诺酮的补充治疗提供新的靶点，以对抗PRP介导的耐药性。相反，了解这些蛋白质的功能机制可能会允许PRP折叠用作开发新蛋白质或肽治疗剂的平台。

DESCRIPTION (provided by applicant): This revised application of a new proposal describes a comprehensive biochemical and biophysical investigation into the `DNA mimicry' of a recently discovered member of the Pentapeptide Repeat Protein (PRP) family of proteins. The atomic resolution structure of the MfpA PRP from Mycobacterium tuberculosis revealed a new protein fold; MfpA's right-handed 2-helical coils yield an elongated structure that is a remarkable mimic of the size, shape and electrostatic surface of DNA. That DNA mimicry is important to the biological role of MfpA is suggested by its ability to confer resistance to fluoro- quinolones by binding DNA gyrase thereby inhibiting its function. We will test the hypothesis that mimicry of the physical properties DNA by MfpA is the heart of its ability to confer drug resistance. Our long term goal is to understand the molecular mechanism by which MfpA and other PRP mediate antibiotic resistance and potentially regulate the enzymatic processing of DNA. MfpA will be developed as a model system for the exploration of DNA mimicry by this newly-discovered and widely-distributed class of proteins. Fluoroquinolones are extremely important antibiotics due to their efficacy against Gram- positive, Gram-negative and mycobacteria. Fluoroquinolones act on DNA gyrase with a unique mechanism of action. They are remarkable for their absence of toxicity and a therapeutic index that is the highest of all currently prescribed antibiotics. The rapid emergence, and spread, of transmissible forms of fluoroquinolone resistance due to the expression of the plasmid-encoded proteins threatens the clinical utility of these antibiotics. The proposed studies seek to understand how the physical properties of the Peptapeptide Repeat Proteins MfpA and Qnr generate resistance to fluoroquinolones. This understanding would provide new targets for therapeutics complementary to fluoroquinolone that would counter the PRP-mediated resistance. Conversely, an understanding of the mechanism by which these proteins function may allow the PRP fold to be used as a platform for the development of novel protein or peptide therapeutics.