The light chain subunit is required for clathrin function in Saccharomyces cerevisiae

Area of Science:

• Cell Biology
• Molecular Biology
• Protein Biochemistry

Background:

• Clathrin, a protein complex vital for intracellular trafficking, consists of heavy (Chc) and light (Clc) chains.
• Disruption of the yeast CLC1 gene (clc1Δ) leads to a significant decrease in Chc levels, complicating the study of Clc function.
• Phenotypic changes in clc1Δ cells might be due to reduced Chc rather than the absence of Clc.

Purpose of the Study:

• To directly investigate the specific functions of clathrin light chains (Clc).
• To determine the role of Clc in clathrin heavy chain (Chc) assembly and vesicle formation.
• To elucidate the necessity of Clc for cellular processes dependent on clathrin-coated vesicles.

Main Methods:

• Generation of yeast clc1Δ strains with elevated Chc expression using a multicopy plasmid.
• Analysis of growth, receptor-mediated endocytosis, and alpha-factor maturation in modified yeast strains.
• Biochemical assays to assess Chc trimerization, coat assembly, and vesicle production.

Main Results:

• Elevated Chc levels partially rescued growth and alpha-factor maturation defects in clc1Δ cells.
• Absence of Clc impaired Chc trimerization and clathrin coat assembly.
• Clathrin coat assembly defects in clc1Δ cells led to impaired vesiculation.

Conclusions:

• Clathrin light chain is indispensable for efficient Chc trimerization.
• Proper formation of clathrin coats and the generation of clathrin-coated vesicles require Clc.
• Clc plays a critical role in intracellular protein trafficking and cellular functions dependent on vesicle formation.