The Pseudomonas aeruginosa 1244 pilin glycan increases susceptibility to human beta defensin 2 but enhances twitching motility.

Abstract

SHANIA DAVIS & JOSEPH HORZEMPA, Department of Biomedical Sciences, West LibertyUniversity, West Liberty, WV USA. The Pseudomonas aeruginosa 1244 pilin glycan increasessusceptibility to human beta defensin 2 but enhances twitching motility. Pseudomonas aeruginosa is an ESKAPE (highly drug resistant) pathogen that is commonlyacquired during hospital stays. This bacterium produces type IV pili which are adhesins andmotor appendages that mediate a surface motility referred to as “twitching.” These pili arepolymers of protein subunits referred to as pilin. The pilin subunit of P. aeruginosa 1244 isglycosylated. Previous studies have shown that the pilin glycan affects the efficiency oftwitching motility under certain conditions and the surface polarity of these fibers. Becausemodulation of the bacterial surface charge has been shown to mediate defensin resistance inother organisms, we tested whether pilin glycosylation affected sensitivity to human betadefensin 2 (HBD-2). Interestingly, the isogenic mutant strain lacking the pilin glycan (1244G7)showed increased resistance to HBD-2 compared to wild type bacteria and those completelylacking a type IV pilus (1244.47). This increased resistance to HBD-2 could explain data from arecent study in which various P. aeruginosa clinical strains were isolated that had pilinglycosylation defects. We also confirmed and extended previous findings that indicated that the1244 pilin glycan enhances twitching motility and we showed that this is especially true onpositively charged surfaces (poly L-lysine coated plastic). However, the positively chargedsurface was also capable of enhancing twitching of strains producing non-glycosylated pili or piliwith an incomplete glycan (1244.2.1).