Peptidoglycan O-acetyltransferase B (PatB) is proposed to catalyze the O-acetylation of the bacterial cell wall polymer, peptidoglycan, at the sixth hydroxyl group of N-acetylmuramic acid (MurNAc). The acetylation modification aids in bacterial survival by preventing the cleavage of the β-1,4-glycosidic bond between MurNAc and N-acetylglucosamine (GlcNAc) of the peptidoglycan by endogenous and exogenous autolysins such as lysozyme. In this study, we exploit PatB’s activity as a tool to incorporate bioorthogonal functionality onto the carbohydrate backbone of peptidoglycan. A range of donors were synthesized in order to probe the promiscuity of PatB. A variety of functional groups were successfully installed on tri-N-acetylglucosamine (GlcNAc)3, a peptidoglycan mimic, including an alkynyl and azido handle. Subsequently, copper (I) catalyzed alkyne azide cycloaddition (CuAAC) was successfully implemented to install a fluorophore at the sixth hydroxyl position. We demonstrate that this methodology can be extended to label intact peptidoglycan and therefore is a useful strategy to identify immunostimulatory cell wall fragments in vitro.

Functionalization of the bacterial cell wall utilizing peptidoglycan O-acetyltransferase B (PatB)

251st National Meeting (2016)

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