Vps68 cooperates with ESCRT-III in intraluminal vesicle formation

Area of Science:

• Cell Biology
• Molecular Biology
• Protein Interactions

Background:

• The endosomal sorting complex required for transport (ESCRT)-III machinery is crucial for forming intraluminal vesicles (ILVs) within multivesicular endosomes.
• Mos10 (Vps60) is an ESCRT-III-associated protein involved in ILV formation.

Purpose of the Study:

• To investigate the function of the newly identified Vps68 protein in ILV formation.
• To elucidate the interaction between Vps68 and the ESCRT-III complex.

Main Methods:

• Stable isotope labeling of amino acids in cell culture (SILAC) coupled with mass spectrometry to identify Vps68 interaction partners.
• Analysis of VPS68 deletion strains to assess ILV formation and ESCRT-III composition.

Main Results:

• Vps68 was identified as a novel interaction partner of the ESCRT-III pathway.
• VPS68 deletion resulted in sorting defects similar to SNF7 deletion under high cargo load.
• ESCRT-III composition was altered in VPS68 deletion strains, with increased core components and decreased associated proteins.
• Vps68 exhibits an unusual membrane topology with amphipathic helices on the luminal side of the endosomal membrane.

Conclusions:

• Vps68 cooperates with ESCRT-III in ILV formation, potentially by weakening membrane leaflets during abscission.
• The findings suggest a role for Vps68 in regulating ESCRT-III function and membrane remodeling during ILV biogenesis.