SKIP controls lysosome positioning using a composite kinesin-1 heavy and light chain-binding domain

Area of Science:

• Cellular Biology
• Molecular Motors
• Protein Interactions

Background:

• The regulation of kinesin-1 microtubule motor activity by cargo recognition is poorly understood.
• Kinesin-1 motors transport various cellular components, including lysosomes, along microtubules.

Purpose of the Study:

• To elucidate the molecular mechanisms governing the interaction between the kinesin-1 motor and its cargo, using the lysosome adaptor SKIP as a model.
• To investigate the roles of kinesin heavy chains (KHCs) and kinesin light chains (KLCs) in cargo binding and motor activation.

Main Methods:

• Utilized SKIP (PLEKHM2) as a model lysosome adaptor.
• Employed mutational analysis to separate KHC and KLC binding sites.
• Investigated SKIP-kinesin-1 interactions in vitro and lysosome transport in vivo.

Main Results:

• Both KHCs and KLCs can recognize cargo binding determinants.
• KHC binding is crucial for SKIP-kinesin-1 interaction in vitro and lysosome transport in vivo.
• KLCs act as gatekeepers, regulating KHC accessibility and relieving motor autoinhibition.

Conclusions:

• A hierarchical, stepwise model for cargo recognition and kinesin-1 activation is proposed.
• Cargo recognition involves initial binding to KLCs, leading to KHC autoinhibition release.
• Dynamic inter- and intra-molecular interactions drive cargo recognition and motor activation.