title: The putative chitin deacetylase of Encephalitozoon cuniculi: a surface protein implicated in microsporidian spore-wall formation.
abstract: Microsporidia are fungal-like unicellular eukaryotes which develop as obligate intracellular parasites. They differentiate into resistant spores that are protected by a thick cell wall composed of glycoproteins and chitin. Despite an extensive description of the fibrillar structure of this wall, very little is known about its protein components and deposit mechanisms. In this study on the human pathogen Encephalitozoon cuniculi, we identify by mass spectrometry the target of polyclonal antibodies previously raised against a 33-kDa protein located at the outer face of the parasite plasma membrane. This 254-amino acid protein is encoded by the ECU11_0510 open reading frame and presents two isoforms of 33 and 55 kDa. Sequence analysis supports an assignment to the polysaccharide deacetylase family with a suspected chitin deacetylase activity (EcCDA). As demonstrated by TEM studies, EcCDA is present at the plasma membrane of the early stages of E. cuniculi life-cycle. At the sporoblast stage, the enzyme accumulates especially in paramural bodies which are convolutions of the plasma membrane opened to the wall. The identification of an EcCDA homologue in the insect parasite Antonospora locustae (ex Nosema locustae) suggests a widespread distribution of this enzyme among Microsporidia. This characterization of a new microsporidian surface protein creates new perspectives to understand spore wall formation and spore resistance.
authors.affiliation: Equipe Parasitologie Moléculaire et Cellulaire, LBP, UMR CNRS 6023, Université Blaise Pascal, Aubière, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Brosson
authors.forename: Lauriane
authors.initials: L
authors.lastname: Kuhn
authors.forename: Gérard
authors.initials: G
authors.lastname: Prensier
authors.forename: Christian P
authors.initials: CP
authors.lastname: Vivarès
authors.forename: Catherine
authors.initials: C
authors.lastname: Texier
mesh_terms: D000581:Amidohydrolases / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D002473:Cell Wall / Q000201:enzymology / Q000502:physiology*; D009670:Encephalitozoon cuniculi / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D046529:Microscopy, Electron, Transmission; D008970:Molecular Weight; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D033761:Spores, Protozoan / Q000201:enzymology
chemical_list: D007527:Isoenzymes; D000581:Amidohydrolases; C019866:chitin deacetylase