Expression of a Clostridium perfringens type IV pilin by Neisseria gonorrhoeae mediates adherence to muscle cells.

Clostridium perfringens is an anaerobic, Gram-positive bacterium that causes a range of diseases in humans, including lethal gas gangrene. We have recently shown that strains of C. perfringens move across the surface of agar plates by a unique type IV pilus (TFP)-mediated social motility that had not been previously described. Based on sequence homology to pilins in Gram-negative bacteria, C. perfringens appears to have two pilin subunits, PilA1 and PilA2. Structural prediction analysis indicated PilA1 is similar to the pseudopilin found in Klebsiella oxytoca, while PilA2 is more similar to true pilins found in the Gram-negative pathogens Pseudomonas aeruginosa and Neisseria gonorrhoeae. Strains of N. gonorrhoeae that were genetically deficient in the native pilin, PilE, but supplemented with inducible expression of PilA1 and PilA2 of C. perfringens were constructed. Genetic competence, wild-type twitching motility, and attachment to human urogenital epithelial cells were not restored by expression of either pilin. However, attachment to mouse and rat myoblast (muscle) cell lines was observed with the N. gonorrhoeae strain expressing PilA2. Significantly, wild-type C. perfringens cells adhered to mouse myoblasts under anaerobic conditions, and adherence was 10-fold lower in a pilT mutant that lacked functional TFP. These findings implicate C. perfringens TFP in the ability of C. perfringens to adhere to and move along muscle fibers in vivo, which may provide a therapeutic approach to limiting this rapidly spreading and highly lethal infection.

Type IV pili-dependent gliding motility in the Gram-positive pathogen Clostridium perfringens and other Clostridia.

Bacteria can swim in liquid media by flagellar rotation and can move on surfaces via gliding or twitching motility. One type of gliding motility involves the extension, attachment and retraction of type IV pili (TFP), which pull the bacterium towards the site of attachment. TFP-dependent gliding motility has been seen in many Gram-negative bacteria but not in Gram-positive bacteria. Recently, the genome sequences of three strains of Clostridium perfringens have been completed and we identified gene products involved in producing TFP in each strain. Here we show that C. perfringens produces TFP and moves with an unusual form of gliding motility involving groups of densely packed cells moving away from the edge of a colony in curvilinear flares. Mutations introduced into the pilT and pilC genes of C. perfringens abolished motility and surface localization of TFP. Genes encoding TFP are also found in the genomes of all nine Clostridium species sequenced thus far and we demonstrated that Clostridium beijerinckii can move via gliding motility. It has recently been proposed that the Clostridia are the oldest Eubacterial class and the ubiquity of TFP in this class suggests that a Clostridia-like ancestor possessed TFP, which evolved into the forms seen in many Gram-negative species.