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AoS28D, a proline-Xaa carboxypeptidase secreted by Aspergillus oryzae

Karine Salamin1, Philippe J Eugster2, Olivier Jousson3

  • 1Service de Dermatologie, Laboratoire de Mycologie, BT422, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.

Applied Microbiology and Biotechnology
|February 24, 2017
PubMed

Insights

Aspergillus oryzae protease AoS28D, a distinct S28 family member, cleaves C-terminal Pro-Xaa bonds. This enzyme may work with other proteases for sequential peptide degradation.

Area of Science:

  • Enzymology
  • Molecular Biology
  • Fungal Proteases

Background:

  • Prolyl peptidases (MEROPS S28 family) are crucial for proline-rich peptide digestion.
  • The Aspergillus oryzae genome encodes four S28 family proteases.
  • Three known proteases (AoS28A, AoS28B, AoS28C) are acidic prolyl endopeptidases.

Purpose of the Study:

  • To characterize the substrate specificity and activity of the divergent Aspergillus oryzae S28 protease, AoS28D.
  • Investigate the unique enzymatic properties of AoS28D compared to other S28 proteases.

Main Methods:

  • BLAST analysis of the Aspergillus oryzae genome to identify S28 family proteases.
  • Gene overexpression in Aspergillus oryzae and Pichia pastoris to produce AoS28D.
  • Enzymatic assays to determine substrate specificity and cleavage sites.

Main Results:

  • AoS28D is a 70-kDa glycoprotein with a 10-kDa sugar moiety.
  • Unlike other S28 proteases, AoS28D does not cleave internal Pro-Xaa bonds.
  • AoS28D selectively cleaves C-terminal Pro-Xaa bonds, similar to human lysosomal Pro-Xaa carboxypeptidase.

Conclusions:

  • AoS28D exhibits unique C-terminal carboxypeptidase activity within the S28 prolyl peptidase family.
  • AoS28D's substrate specificity suggests a role in synergistic peptide degradation with other secreted enzymes.
  • This finding expands our understanding of fungal protease functions in sequential protein catabolism.
Keywords:
Angiotensin IAspergillus oryzaeBradykininProline-Xaa carboxypeptidaseProlyl peptidase

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