title: Analysis of secreted proteins during conidial germination of Aspergillus oryzae RIB40.
abstract: To broaden our understanding of extracellular proteins of Aspergillus oryzae at the conidial germination stage, analyses of the secreted proteins during germination were carried out. Taka-amylase A (TAA), glucoamylase (GLAA), and aspergillopepsin A (PEPA) were identified as the main products by peptide mass fingerprinting. TAA and PEPA were detected simultaneously with the formation of germ tubes. With the development of germination, the pH of the medium fell from 5.5 to 3.5. The secreted PEPA had a pro-sequence and likely shifted from 42 kDa to 41 kDa below pH 4.6, indicating that the precursor of PEPA was secreted and underwent pH-dependent processing. Furthermore, the 41 kDa protein was trapped by the addition of pepstatin A, the specific inhibitor of PEPA, suggesting that the maturation of pro-PEPA was a stepwise autoprocessing upon acidification of the medium and itself was an intermediate of the processing. It was implied that PEPA plays an important role at the early germination stage.
authors.affiliation: Department of Agriscience and Bioscience, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan.
authors.forename: Li Ying
authors.initials: LY
authors.lastname: Zhu
authors.forename: Cong Ha
authors.initials: CH
authors.lastname: Nguyen
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Sato
authors.forename: Michio
authors.initials: M
authors.lastname: Takeuchi
mesh_terms: D016282:Aspartic Acid Endopeptidases / Q000032:analysis / Q000378:metabolism; D001236:Aspergillus oryzae / Q000737:chemistry* / Q000254:growth & development; D004591:Electrophoresis, Polyacrylamide Gel; D005656:Fungal Proteins / Q000032:analysis / Q000378:metabolism*; D005087:Glucan 1,4-alpha-Glucosidase / Q000032:analysis / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D010449:Peptide Mapping; D011498:Protein Precursors; D011499:Protein Processing, Post-Translational; D016622:Silver Staining; D000516:alpha-Amylases / Q000032:analysis / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D011498:Protein Precursors; D000516:alpha-Amylases; D005087:Glucan 1,4-alpha-Glucosidase; D016282:Aspartic Acid Endopeptidases; C029094:aspergillopepsin I