title: α-(1,4)-Amylase, but not α- and β-(1,3)-glucanases, may be responsible for the impaired growth and morphogenesis of Paracoccidioides brasiliensis induced by N-glycosylation inhibition.
abstract: The cell wall of Paracoccidioides brasiliensis, which consists of a network of polysaccharides and glycoproteins, is essential for fungal pathogenesis. We have previously reported that N-glycosylation of proteins such as N-acetyl-β-D-glucosaminidase is required for the growth and morphogenesis of P. brasiliensis. In the present study, we investigated the influence of tunycamicin (TM)-mediated inhibition of N-linked glycosylation on α- and β-(1,3)-glucanases and on α-(1,4)-amylase in P. brasiliensis yeast and mycelium cells. The addition of 15 µg/ml TM to the fungal cultures did not interfere with either α- or β-(1,3)-glucanase production and secretion. Moreover, incubation with TM did not alter α- and β-(1,3)-glucanase activity in yeast and mycelium cell extracts. In contrast, α-(1,4)-amylase activity was significantly reduced in underglycosylated yeast and mycelium extracts after exposure to TM. In spite of its importance for fungal growth and morphogenesis, N-glycosylation was not required for glucanase activities. This is surprising because these activities are directed to wall components that are crucial for fungal morphogenesis. On the other hand, N-glycans were essential for α-(1,4)-amylase activity involved in the production of malto-oligosaccharides that act as primer molecules for the biosynthesis of α-(1,3)-glucan. Our results suggest that reduced fungal α-(1,4)-amylase activity affects cell wall composition and may account for the impaired growth of underglycosylated yeast and mycelium cells.
authors.affiliation: Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900, Ribeirão Preto, SP, 14049-900, Brasil.
authors.forename: Fausto Bruno
authors.initials: FB
authors.lastname: Dos Reis Almeida
authors.forename: Laurine Lacerda
authors.initials: LL
authors.lastname: Pigosso
authors.forename: André Ricardo
authors.initials: AR
authors.lastname: de Lima Damásio
authors.forename: Valdirene Neves
authors.initials: VN
authors.lastname: Monteiro
authors.forename: Célia Maria
authors.initials: CM
authors.lastname: de Almeida Soares
authors.forename: Roberto Nascimento
authors.initials: RN
authors.lastname: Silva
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Roque-Barreira
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D043326:Glucan 1,3-beta-Glucosidase / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006031:Glycosylation / Q000187:drug effects*; D010228:Paracoccidioides / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development*; D014415:Tunicamycin / Q000494:pharmacology*; D000516:alpha-Amylases / Q000378:metabolism*
chemical_list: D000890:Anti-Infective Agents; D014415:Tunicamycin; D006026:Glycoside Hydrolases; D000516:alpha-Amylases; D043326:Glucan 1,3-beta-Glucosidase; C021780:exo-1,3-alpha-glucanase
keywords: N-glycan; Paracoccidioides brasiliensis; amylase; cell wall; glucanase