Interaction between VPS13A and the XK scramblase is required to prevent VPS13A disease in humans
VPS13 family proteins form conduits between the membranes of different organelles through which lipids are transferred. In humans there are four VPS13 paralogs each of which is required to prevent a different inherited disorder. VPS13 proteins contain multiple conserved domains. The VAB domain binds to adaptor proteins to recruit VPS13 to specific membrane contact sites. This work demonstrates the importance of a different domain in VPS13A in preventing VPS13A disease (chorea-acanthocytosis). The Pleckstrin Homology (PH) domain at the C-terminus of VPS13A is required to form a complex with the XK scramblase and for proper localization of VPS13A within the cell. Mutations in the interaction surface between VPS13A and XK predicted by Alphafold modeling disrupt complex formation and colocalization of the two proteins. Mutant VPS13A alleles found in patients with VPS13A disease truncate the PH domain. The phenotypic similarities between VPS13A disease and McLeod syndrome caused by mutations in XK argue that loss of VPS13A-XK complex is the basis of both diseases. Summary StatementVPS13A disease and McLeod syndrome are related disorders caused by mutation of the VPS13A and XK genes, respectively. A pathologic VPS13A mutation disrupts binding of the VPS13A and XK proteins, suggesting a common basis of both diseases.