Bile‐induced peptidoglycan remodelling in S almonella enterica

Abstract

Summary Changes in the peptidoglycan ( PG ) structure of S almonella enterica are detected in the presence of a sublethal concentration of sodium deoxycholate ( DOC ): (i) lower proportions of B raun lipoprotein ( Lpp )‐bound muropeptides; (ii) reduced levels of muropeptides cross‐linked by L (meso)‐diaminopimelyl‐ D (meso)‐diaminopimelic acid ( L ‐ D ) peptide bridges (3‐3 cross‐links). Similar structural changes are found in S . enterica cultures adapted to grow in the presence of a lethal concentration of DOC , suggesting that reduced anchoring of B raun protein to PG and low occurrence of 3‐3 cross‐links may increase S . enterica resistance to bile. This view is further supported by additional observations: (i) A triple mutant lacking L , D ‐transpeptidases YbiS , ErfK , and YcfS , which does not contain Lpp anchored to PG , is hyper‐resistant to bile; (ii) enhanced 3‐3 cross‐linking upon overexpression of YnhG transpeptidase causes a decrease in bile resistance. These observations suggest that remodelling of the cell wall may be added to the list of adaptive responses that permit survival of S . enterica in the presence of bile.

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