Vps60 initiates alternative ESCRT-III filaments

Area of Science:

• Cell Biology
• Molecular Biology
• Evolutionary Biology

Background:

• The Endosomal Sorting Complex Required for Transport-III (ESCRT-III) machinery is crucial for various cellular processes, including cell division and endosome maturation.
• Evolutionary diversification of ESCRT-III subunits may have led to novel cellular functions.

Purpose of the Study:

• To characterize a novel ESCRT-III copolymer initiated by Vps60.
• To investigate the functional distinctness of Vps60- and Snf7-based ESCRT-III polymers.

Main Methods:

• Investigated Vps60 polymerization and recruitment of downstream ESCRT-III subunits (Vps2, Vps24, Did2, Ist1).
• Utilized fibroblast cell models to compare the localization and recruitment dynamics of Vps60/CHMP5 and Snf7/CHMP4 during cellular functions.
• Examined recruitment during endosomal functions, cytokinesis, and nuclear envelope reformation.

Main Results:

• Vps60 forms membrane-bound polymers that recruit specific downstream subunits, similar to Snf7.
• Snf7- and Vps60-based filaments coexist on membranes but remain spatially and biochemically segregated.
• Vps60/CHMP5 and Snf7/CHMP4 exhibit distinct localization and recruitment dynamics during endosomal functions and cytokinesis, with Vps60/CHMP5 not recruited during nuclear envelope reformation.

Conclusions:

• Vps60 and Snf7 initiate functionally distinct ESCRT-III polymers.
• The diversification of ESCRT-III subunits is linked to the acquisition of new cellular functions.