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 Liberty
University, West Liberty, WV USA. The Pseudomonas aeruginosa 1244 pilin glycan increases
susceptibility to human beta defensin 2 but enhances twitching motility.

Pseudomonas aeruginosa is an ESKAPE (highly drug resistant) pathogen that is commonly
acquired during hospital stays. This bacterium produces type IV pili which are adhesins and
motor appendages that mediate a surface motility referred to as “twitching.” These pili are
polymers of protein subunits referred to as pilin. The pilin subunit of P. aeruginosa 1244 is
glycosylated. Previous studies have shown that the pilin glycan affects the efficiency of
twitching motility under certain conditions and the surface polarity of these fibers. Because
modulation of the bacterial surface charge has been shown to mediate defensin resistance in
other organisms, we tested whether pilin glycosylation affected sensitivity to human beta
defensin 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 completely
lacking a type IV pilus (1244.47). This increased resistance to HBD-2 could explain data from a
recent study in which various P. aeruginosa clinical strains were isolated that had pilin
glycosylation defects. We also confirmed and extended previous findings that indicated that the
1244 pilin glycan enhances twitching motility and we showed that this is especially true on
positively charged surfaces (poly L-lysine coated plastic). However, the positively charged
surface was also capable of enhancing twitching of strains producing non-glycosylated pili or pili
with an incomplete glycan (1244.2.1).