An N-end rule pathway that recognizes proline and destroys gluconeogenic enzymes

Area of Science:

• Cellular biology
• Biochemistry
• Molecular mechanisms of protein degradation

Background:

• Cells regulate glucose metabolism by synthesizing glucose when deprived and degrading gluconeogenic enzymes when glucose is abundant.
• Understanding the precise mechanisms of enzyme degradation is crucial for metabolic control.

Purpose of the Study:

• To identify the molecular players and recognition motifs involved in the targeted degradation of gluconeogenic enzymes in Saccharomyces cerevisiae.
• To elucidate the role of the GID ubiquitin ligase complex in this process.

Main Methods:

• Investigated the function of the Gid4 subunit of the GID ubiquitin ligase complex.
• Analyzed the recognition of specific amino acid sequences and positions within gluconeogenic enzymes.
• Utilized yeast (Saccharomyces cerevisiae) as a model organism.

Main Results:

• The Gid4 subunit targets key gluconeogenic enzymes (Fbp1, Icl1, Mdh2) for degradation.
• Gid4 recognizes N-terminal proline residues and adjacent sequence motifs.
• Gid4 also recognizes proline at position 2 of Pck1, contributing to its degradation.
• Identified Gid4 as the recognition component of the Pro/N-end rule pathway.

Conclusions:

• Gid4 acts as a crucial recognition factor in the GID-mediated proteolytic pathway.
• The Pro/N-end rule pathway degrades gluconeogenic enzymes based on specific proline-containing motifs.
• This pathway plays a significant role in regulating glucose metabolism in yeast.