Identification of the amidotransferase AsnB1 as being responsible for meso-diaminopimelic acid amidation in lactobacillus plantarum peptidoglycan

Bernard , Elvis
        INRA
        , Jouy-En-Josas .
         UMR 1319 MICrobiologie de l'ALImentation au Service de la Santé Humaine; Rolain , Thomas
        . Biochimie et Génétique Moléculaire Bactérienne, Institut des Sciences de la Vie; Courtin , Pascal
        INRA
        , Jouy-En-Josas .
         UMR 1319 MICrobiologie de l'ALImentation au Service de la Santé Humaine; Hols , Pascal
        . Biochimie et Génétique Moléculaire Bactérienne, Institut des Sciences de la Vie; Chapot-Chartier , Marie-Pierre
        INRA
        , Jouy-En-Josas .
         UMR 1319 MICrobiologie de l'ALImentation au Service de la Santé Humaine

Identification of the amidotransferase AsnB1 as being responsible for meso-diaminopimelic acid amidation in lactobacillus plantarum peptidoglycan

2011

Bernard , Elvis (INRA , Jouy-En-Josas (France). UMR 1319 MICrobiologie de l'ALImentation au Service de la Santé Humaine) | Rolain , Thomas (Université Catholique de Louvain, Louvain-la-Neuve(Belgique). Biochimie et Génétique Moléculaire Bactérienne, Institut des Sciences de la Vie) | Courtin , Pascal (INRA , Jouy-En-Josas (France). UMR 1319 MICrobiologie de l'ALImentation au Service de la Santé Humaine) | Hols , Pascal (Université Catholique de Louvain, Louvain-la-Neuve(Belgique). Biochimie et Génétique Moléculaire Bactérienne, Institut des Sciences de la Vie) | Chapot-Chartier , Marie-Pierre(auteur de correspondance) (INRA , Jouy-En-Josas (France). UMR 1319 MICrobiologie de l'ALImentation au Service de la Santé Humaine)

The peptidoglycan (PG) of Lactobacillus plantarum contains amidated meso-diaminopimelic acid (mDAP). The functional role of this PG modification has never been characterized in any bacterial species, except for its impact on PG recognition by receptors of the innate immune system. In silico analysis of loci carrying PG biosynthesis genes in the L. plantarum genome revealed the colocalization of the murE gene, which encodes the ligase catalyzing the addition of mDAP to UDP-N-muramoyl-D-glutamate PG precursors, with asnB1, which encodes a putative asparagine synthase with an N-terminal amidotransferase domain. By gene disruption and complementation experiments, we showed that asnB1 is the amidotransferase involved in mDAP amidation. PG structural analysis revealed that mDAP amidation plays a key role in the control of the L,D-carboxypeptidase DacB activity. In addition, a mutant strain with a defect in mDAP amidation is strongly affected in growth and cell morphology, with filamentation and cell chaining, while a DacB-negative strain displays a phenotype very similar to that of a wild-type strain. These results suggest that mDAP amidation may play a critical role in the control of the septation process.

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