Accumulation of Peptidoglycan O-Acetylation Leads to Altered Cell Wall Biochemistry and Negatively Impacts Pathogenesis Factors of Campylobacter jejuni *

摘要

Campylobacter jejuni is a leading cause of bacterial gastroenteritis in the developed world. Despite its prevalence, its mechanisms of pathogenesis are poorly understood. Peptidoglycan (PG) is important for helical shape, colonization, and host-pathogen interactions in C. jejuni . Therefore, changes in PG greatly impact the physiology of this organism. O - a cetylation of p eptidoglycan (OAP) is a bacterial phenomenon proposed to be important for proper cell growth, characterized by acetylation of the C6 hydroxyl group of N -acetylmuramic acid in the PG glycan backbone. The OAP gene cluster consists of a PG O -acetyltransferase A ( patA ) for translocation of acetate into the periplasm, a PG O -acetyltransferase B ( patB ) for O -acetylation, and an O -acetylpeptidoglycan esterase ( ape1 ) for de- O -acetylation. In this study, reduced OAP in Δ patA and Δ patB had minimal impact on C. jejuni growth and fitness under the conditions tested. However, accumulation of OAP in Δ ape1 resulted in marked differences in PG biochemistry, including O -acetylation, anhydromuropeptide levels, and changes not expected to result directly from Ape1 activity. This suggests that OAP may be a form of substrate level regulation in PG biosynthesis. Ape1 acetylesterase activity was confirmed in vitro using p -nitrophenyl acetate and O -acetylated PG as substrates. In addition, Δ ape1 exhibited defects in pathogenesis-associated phenotypes, including cell shape, motility, biofilm formation, cell surface hydrophobicity, and sodium deoxycholate sensitivity. Δ ape1 was also impaired for chick colonization and adhesion, invasion, intracellular survival, and induction of IL-8 production in INT407 cells in vitro . The importance of Ape1 in C. jejuni biology makes it a good candidate as an antimicrobial target.