title: Protein O-mannosyltransferase A of Aspergillus awamori is involved in O-mannosylation of glucoamylase I.
abstract: Industrially important extracellular enzymes from filamentous fungi are often O-mannosylated. The structure and function of the pmtA (AapmtA) gene encoding the protein O-D-mannosyltransferase of Aspergillus awamori were characterized. The AapmtA disruptant, designated AaPMTA, was constructed by homologous recombination. The strain AaPMTA exhibited fragile cell morphology with respect to hyphal extension, as well as swollen hyphae formation and conidia formation in potato dextrose medium. Moreover, the AapmtA disruptant showed increased sensitivity to high temperature and Congo red. Thus, the AaPmtA protein is involved in the formation of the normal cell wall. The strain AaPMTA could grow well in liquid synthetic medium and secrete glucoamylase I (GAI-AaPMTA) to a similar extent to the wild-type strain (GAI-WT). Matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis of the GAIs revealed that approximately 33 mannose moieties of GAI were absent in strain AaPMTA. This result indicates that the AaPmtA protein is responsible for the transfer of mannose to GAI. Structural analysis of the O-linked oligosaccharides of GAI also demonstrated that the AapmtA disruption resulted in a reduction of the amounts of O-linked oligosaccharides, such as D-mannose and alpha-1,2-mannotriose, in GAI-AaPMTA. However, the amount of alpha-1,2-mannobiose was comparable between GAI-WT and GAI-AaPMTA. The result suggests the presence of a compensatory mechanism in the synthetic pathway of O-mannosylation in A. awamori.
authors.affiliation: Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Fukuoka 812-8581, Japan.
authors.forename: Takuji
authors.initials: T
authors.lastname: Oka
authors.affiliation: Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Fukuoka 812-8581, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Sameshima
authors.affiliation: Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Fukuoka 812-8581, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Koga
authors.affiliation: Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Fukuoka 812-8581, Japan.
authors.forename: Hoon
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Fukuoka 812-8581, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Goto
authors.affiliation: Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Fukuoka 812-8581, Japan.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Furukawa
mesh_terms: D001230:Aspergillus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D002473:Cell Wall; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D005816:Genetic Complementation Test; D005087:Glucan 1,4-alpha-Glucosidase / Q000378:metabolism*; D006031:Glycosylation; D008364:Mannosyltransferases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D005656:Fungal Proteins; D009844:Oligosaccharides; C499685:PmtA protein, Aspergillus nidulans; D008364:Mannosyltransferases; C082696:protein O-mannosyltransferase; D005087:Glucan 1,4-alpha-Glucosidase