Candida parapsilosis expresses and secretes two aspartic proteinases

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M Fusek1, E A Smith, M Monod

  • 1Laboratory of Protein Crystallography, Oklahoma Medical Research Foundation, Oklahoma City 73104.

FEBS Letters
|July 19, 1993
PubMed

Insights

Candida parapsilosis secretes two distinct aspartic proteinases. A newly identified minor proteinase, previously thought to be a pseudogene, is actively expressed and secreted by the CHUV E-18 strain.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Candida parapsilosis is a fungal pathogen known to secrete aspartic proteinases.
  • Previous research identified a primary aspartic proteinase from the CHUV E-18 strain.
  • A potential secondary aspartic proteinase gene was previously identified but considered a pseudogene.

Purpose of the Study:

  • To isolate and characterize a second aspartic proteinase from Candida parapsilosis CHUV E-18.
  • To compare the properties of this minor proteinase with the previously identified major proteinase.
  • To determine the identity and expression status of the minor aspartic proteinase.

Main Methods:

  • Isolation and characterization of secreted proteinases.
  • Biochemical analysis including molecular weight and pH optimum determination.
  • Isoelectric focusing and substrate specificity assays.
  • Amino-terminal amino acid sequencing.

Main Results:

  • A second aspartic proteinase was isolated and characterized from C. parapsilosis CHUV E-18.
  • This minor proteinase constitutes approximately 25% of the total secreted proteinase production.
  • It shares a similar molecular weight and pH optimum with the major proteinase but differs in isoelectric point and substrate specificity.
  • Amino-terminal sequencing confirmed this proteinase corresponds to the sequence previously annotated as a pseudogene.

Conclusions:

  • The CHUV E-18 strain of Candida parapsilosis expresses and secretes two distinct aspartic proteinases.
  • The previously identified pseudogene is actively transcribed and translated into a functional, secreted proteinase.
  • This finding expands our understanding of the proteinase repertoire in Candida parapsilosis.

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