Replacing the 238th aspartic acid with an arginine impaired the oligomerization activity and inflammation-inducing property of pyolysin

ABSTRACTTrueperella pyogenes (T. pyogenes) is an important opportunistic pathogen. Pyolysin (PLO) importantly contributes to the pathogenicity of T. pyogenes. However, the relationship between the structure and function and the virulence of PLO is not well documented. In the current study, recombinant PLO (rPLO) and three rPLO mutants were prepared. rPLO D238R, a mutant with the 238th aspartic acid replaced with an arginine, showed impairment in oligomerization activity on cholesterol-containing liposome and pore-forming activity on sheep red blood cell membrane. Further study employing the prepared mutants confirmed that the pore-forming activity of PLO is essential for inducing excessive inflammation responses in mice by upregulating the expression levels of IL-1β, TNF-α, and IL-6. By contrast, rPLO P499F, another mutant with impaired cell membrane binding capacity, elicited an inflammation response that was dependent on pathogen-associated molecular pattern (PAMP) activity, given that the mutant signif...