Characterization of A. actinomycetemcomitans leukotoxin mutants

描述（由申请人提供）：a .放线菌comitans是一种革兰氏阴性细菌，是局部侵袭性牙周炎（LAP）的病原体。放线菌也是与有效心内膜炎有关的重要HACECK细菌群的一员。它的一种毒力因子是一种强效的白质毒素，它能特异性地杀死白细胞，也能破坏红细胞。白质毒素是RTX毒素的一员。目前关于放线菌单胞菌白毒素生物合成的大部分知识是基于与其他细菌系统（如大肠杆菌）的相似性，但这些系统与放线菌单胞菌之间存在一些差异。我们建议研究放线菌a .放线菌comitans中白毒素的生物合成，以扩大我们对该生物的生理和发病机制的认识，从而更好地理解白毒素作为毒力因子的作用。更具体地说，我们提出的研究旨在：1。参与白毒素生物合成的新基因的特征。我们已经分离出白质毒素突变体，有几个突变体位于白质毒素操纵子之外。我们提出的实验将识别和表征突变的性质。2. 测定ItxC在白毒素修饰和活性中的作用。我们提出的实验将使我们能够研究ItxC突变体中白毒素的修饰，并确定ItxC对白毒素活性的作用。这项研究将扩大我们对放线菌产生白毒素的遗传学知识。放线菌是一种口腔病原体，可引起牙周病和心脏病。我们正在研究这种细菌产生的一种毒素的合成所涉及的遗传学。我们的目标是了解这种毒素在疾病中的作用，希望提高我们预防或治疗由放线菌引起的疾病的能力。

DESCRIPTION (provided by applicant): A. actinomycetemcomitans, a gram-negative bacterium, is the causative agent of localized aggressive periodontitis (LAP). A. actinomycetemcomitans is also a member of the important HACECK group of bacteria implicated in enfective endocarditis. One of its virulence factors, a potent leukotoxin, kills specifically white blood cells and can also destroy erythrocytes. Leukotoxin is a member of the RTX toxins. Much of the present knowledge in the biosynthesis of leukotoxin in A. actinomycetemcomitans is based on similarity with other bacterial systems, such as E. coli, but some differences exist between those systems and A. actinomycetemcomitans. We propose to study the biosynthesis of leukotoxin in A. actinomycetemcomitans to expand our knowledge of the physiology and pathogenesis of this organism which can lead to a better understanding of the role played by leukotoxin as virulence factor. More specifically, we propose studies that aim to: 1. Characterize of novel genes involved in leukotoxin biosynthersis. We have isolated leukotoxin mutants, and several mutations map somewhere outside of the leukotoxin operon. We propose experiments that will identify and characterize the nature of the mutations. 2. Determine the function of ItxC in the modification and activiy of leukotoxin. We propose experiments that will allow us to study modification of leukotoxin in ItxC mutants and to determine the role of ItxC on the activity of leukotoxin. This study will expand our knowledge of the genetics of leukotoxin production in A. actinomycetemcomitans. A. actinomycetemcomitans, an oral pathogen, causes periodontal and heart disease. We are studying the genetics involved in the synthesis of a toxin produced by this bacterium. It is our goal to understand the role played by this toxin in the disease with the hopes of enhancing our ability to prevent or treat diseases caused by A. actinomycetemcomitans.