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Updated: Oct 4, 2026

Production and Visualization of Bacterial Spheroplasts and Protoplasts to Characterize Antimicrobial Peptide Localization
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Production and Visualization of Bacterial Spheroplasts and Protoplasts to Characterize Antimicrobial Peptide Localization

Published on: August 11, 2018

Intracellular localization of two molecular forms of membrane acid protease in Aspergillus oryzae

Y Tsujita, A Endo

    Journal of Biochemistry
    |July 1, 1980
    PubMed

    Insights

    This study investigated the location of two Aspergillus oryzae acid proteases (M1 and M2). Most M2 was released from cells, while M1 and M2 were found in cellular membranes, likely on the cytoplasmic surface.

    Area of Science:

    • Biochemistry
    • Molecular Biology
    • Enzymology

    Background:

    • Aspergillus oryzae produces membrane-bound acid proteases (M1 and M2) with EC 3.4.23.6.
    • Understanding enzyme localization is crucial for elucidating cellular functions.

    Purpose of the Study:

    • To determine the intracellular localization of Aspergillus oryzae membrane-bound acid proteases M1 and M2.
    • To investigate the distribution of these proteases within cellular compartments.

    Main Methods:

    • Treatment of Aspergillus oryzae mycelia with wall-lytic enzymes.
    • Mechanical disruption of mycelia to obtain cell wall fractions.
    • Subcellular fractionation of membranes from burst spheroplasts.
    • Analysis of acid protease activity in different cellular fractions.

    Main Results:

    • Most M2 protease was solubilized and released from mycelia treated with wall-lytic enzymes.
    • Cell wall fractions contained less than 5% of total acid protease activity.
    • Acid proteases M1 and M2 were found in both rough and smooth microsomes.
    • M1 was predominant in rough microsomes, and M2 in smooth microsomes, suggesting localization on cytoplasmic membranes.

    Conclusions:

    • Aspergillus oryzae acid proteases M1 and M2 are primarily associated with intracellular membranes, not the cell wall.
    • M1 and M2 exhibit differential localization within microsomal fractions, potentially on the cytoplasmic membrane surface.

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