A novel protease from yeast with specificity towards paired basic residues.

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• Prohormone processing in eukaryotes frequently involves cleavage at paired basic residues.
• Specific proteases responsible for these cleavages have remained unidentified.
• Yeast Saccharomyces cerevisiae alpha-cells process alpha-mating factor precursor at paired basic residues (Lys-Arg).

Purpose of the Study:

• To identify and characterize novel proteases involved in prohormone processing.
• To investigate the enzyme responsible for cleaving paired basic residues in yeast alpha-mating factor precursor.
• To understand the substrate specificity of candidate prohormone processing enzymes.

Main Methods:

• Protease identification in yeast cell lysates.
• Enzyme purification and molecular weight determination.
• Substrate specificity analysis using various peptide substrates.

Main Results:

• A novel protease, named propheromone-convertase Y, was identified and purified from yeast.
• The enzyme has a molecular weight of approximately 43,000 Da.
• Propheromone-convertase Y specifically cleaves peptide bonds at paired basic residues, but not at single basic residues, distinguishing it from trypsin-like proteases.

Conclusions:

• Propheromone-convertase Y is a novel protease with unique specificity for paired basic residues.
• This enzyme is likely involved in the in vivo processing of yeast propheromone.
• The findings provide a candidate enzyme for prohormone processing and open avenues for studying similar enzymes in other species.