Identification of the L,D-Transpeptidases for Peptidoglycan Cross-linking in Escherichia coli

INSERM, U872, LRMA, Centre de Recherche des Cordeliers, Equipe 12, Paris, F-75006 France; Université Pierre et Marie Curie – Paris 6, UMR S 872, Paris, F-75006 France; Université Paris Descartes, UMR S 872, Paris, F-75006 France; Muséum National d'Histoire Naturelle, Plateforme de Spectrométrie de Masse et de Protéomique; AP-HP, Hôpital Européen Georges Pompidou, Paris, F-75015 France

	Abstract

Three active site cysteine L,D-transpeptidases can individually anchor the Braun lipoprotein to the Escherichia coli peptidoglycan. Here, we show that two additional enzymes of the same family form peptide bonds between the third residues of peptidoglycan stems generating meso-DAP³meso-DAP³ unusual cross-links. This activity partially replaces the D,D-transpeptidase activity of penicillin-binding proteins.