Functional Characterization of the <i>N</i>-Acetylmuramyl-<span style="font-variant: small-caps">l</span>-Alanine Amidase, Ami1, from <i>Mycobacterium abscessus</i>
Tanja Küssau,
Niël Van Wyk,
Matt D. Johansen,
Husam M. A. B. Alsarraf,
Aymeric Neyret,
Claire Hamela,
Kasper K. Sørensen,
Mikkel B. Thygesen,
Claire Beauvineau,
Laurent Kremer,
Mickaël Blaise
Affiliations
Tanja Küssau
Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS UMR 9004, CEDEX 5, 34293 Montpellier, France
Niël Van Wyk
Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS UMR 9004, CEDEX 5, 34293 Montpellier, France
Matt D. Johansen
Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS UMR 9004, CEDEX 5, 34293 Montpellier, France
Husam M. A. B. Alsarraf
Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS UMR 9004, CEDEX 5, 34293 Montpellier, France
Aymeric Neyret
CEMIPAI CNRS UM UMS3725, CEDEX 5, 34293 Montpellier, France
Claire Hamela
Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS UMR 9004, CEDEX 5, 34293 Montpellier, France
Kasper K. Sørensen
Department of Chemistry, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
Mikkel B. Thygesen
Department of Chemistry, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
Claire Beauvineau
Chemical Library Institut Curie/CNRS, CNRS UMR9187, INSERM U1196 and CNRS UMR3666, INSERM U1193, Université Paris-Saclay, F-91405 Orsay, France
Laurent Kremer
Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS UMR 9004, CEDEX 5, 34293 Montpellier, France
Mickaël Blaise
Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS UMR 9004, CEDEX 5, 34293 Montpellier, France
Peptidoglycan (PG) is made of a polymer of disaccharides organized as a three-dimensional mesh-like network connected together by peptidic cross-links. PG is a dynamic structure that is essential for resistance to environmental stressors. Remodeling of PG occurs throughout the bacterial life cycle, particularly during bacterial division and separation into daughter cells. Numerous autolysins with various substrate specificities participate in PG remodeling. Expression of these enzymes must be tightly regulated, as an excess of hydrolytic activity can be detrimental for the bacteria. In non-tuberculous mycobacteria such as Mycobacterium abscessus, the function of PG-modifying enzymes has been poorly investigated. In this study, we characterized the function of the PG amidase, Ami1 from M. abscessus. An ami1 deletion mutant was generated and the phenotypes of the mutant were evaluated with respect to susceptibility to antibiotics and virulence in human macrophages and zebrafish. The capacity of purified Ami1 to hydrolyze muramyl-dipeptide was demonstrated in vitro. In addition, the screening of a 9200 compounds library led to the selection of three compounds inhibiting Ami1 in vitro. We also report the structural characterization of Ami1 which, combined with in silico docking studies, allows us to propose a mode of action for these inhibitors.