STRUCTURE-FUNCTION ASPECTS OF ACTINOBACILLUS-ACTINOMYCETEMCOMITANS LEUKOTOXIN

ACTINOBACILLUS ACTINOMYCETEMCOMITANS has been implicated as a causativ e organism in early-onset periodontitis. The mechanisms by which A. ac tinomycetemcomitans is pathogenic are not known, but the organism prod uces several potential virulence factors, one of which is a leukotoxin . As a group, bacterial protein toxins are made up of structural domai ns which control various aspects of toxic activity, such as target cel l recognition, membrane insertion, and killing. The purpose of this ar ticle is to review the structure of RTX, with special emphasis to its relation to toxin function. In addition, we will propose a model based upon other bacterial proteins whereby the water-soluble A. actinomyce temcomitans leukotoxin is able to achieve insertion into a biological membrane.