Modulation of Ras and a-factor function by carboxyl-terminal proteolysis

Area of Science:

• Molecular Biology
• Proteomics
• Yeast Genetics

Background:

• Prenylated proteins are essential for cellular functions, with maturation involving carboxyl-terminal processing.
• This processing is critical for the proper localization and signaling of key proteins like Ras.
• Understanding the enzymes involved is key to deciphering protein maturation pathways.

Purpose of the Study:

• To identify the genes responsible for the proteolytic processing of prenylated proteins in Saccharomyces cerevisiae.
• To elucidate the specific roles of the identified genes, RCE1 and AFC1, in protein maturation.
• To investigate the functional consequences of impaired prenylated protein processing on cellular signaling.

Main Methods:

• Gene identification and deletion in Saccharomyces cerevisiae.
• Biochemical assays to assess proteolytic processing of prenylated proteins.
• Analysis of protein localization and signaling pathways, including Ras protein function.

Main Results:

• Two genes, RCE1 and AFC1, were identified as essential for prenylated protein processing.
• Afc1 functions as a zinc protease involved in yeast a-factor processing.
• Rce1 is involved in processing both Ras protein and a-factor; its disruption affects Ras localization, signaling, and suppresses specific RAS2 mutations.

Conclusions:

• RCE1 and AFC1 are the primary genes responsible for the proteolytic maturation of prenylated proteins in yeast.
• The identified proteases play distinct yet overlapping roles in processing critical signaling proteins.
• Impaired processing of prenylated proteins leads to significant defects in cellular localization and signal transduction pathways.