Leukotoxin production by A. actinomycetemcomitans

描述：放线菌是一种细菌，是局部侵袭性牙周炎（LAP）的病原。LAP是一种影响青少年的破坏性和侵袭性口腔疾病。LAP的发病率因人口群体而异，但少数民族和弱势群体的发病率更高。不治疗LAP会导致牙齿脱落和其他健康相关问题。此外，放线菌是HACEK细菌群的一部分，可引起感染性心内膜炎，这是一种心脏瓣膜和组织疾病。

DESCRIPTION: Actinobacillus actinomycetemcomitans is a bacterium that is the etiologic agent for localized aggressive periodontitis (LAP). LAP is a destructive and aggressive disease of the oral cavity that affects adolescents. The incidence of LAP varies among population groups, but afflicts minorities and the underprivileged at a higher frequency. Failure to treat LAP results in the loss of teeth and other health-related problems. In addition, A. actinomycetemcomitans is part of the HACEK group of bacteria that causes infective endocarditis, a disease of heart valves and tissue. A. actinomycetemcomitans secretes a protein toxin known as leukotoxin. Leukotoxin destroys leukocytes of humans, and likely plays a significant role in the pathogenesis of A. actinomycetemcomitans by helping the bacterium evade the immune response. Leukotoxin is an RTX (repeats in toxin) toxin that includes other important toxins such as E. coil alpha-hemolysin, M. haemolytica leukotoxin, B. pertussis adenylate cyclase, and V. cholerae RTX toxin. To date, little is known about how A. actinomycetemcomitans leukotoxin is produced, activated, and secreted from bacterial cells. In addition, none of the RTX toxins have been crystallized to have their three-dimensional structures solved. Proposed here are experiments that will (1) identify the genes that are required for production of active leukotoxin, (2) study the genes and proteins using genetic and biochemical approaches, and (3) grow crystals of leukotoxin and solve its three-dimensional structure at the atomic level. We expect this work to lead to a better understanding of leukotoxin production and how the toxin contributes to disease. The structural information gained through these experiments will shed more light on the mechanism of action of this important class of toxins. This new information may lead to the design of therapeutic agents that can disrupt leukotoxin activity and ultimately treat or prevent disease.