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FFAT motif phosphorylation controls formation and lipid transfer function of inter-organelle contacts

ABSTRACT: Organelles are physically connected in membrane contact sites. The endoplasmic reticulum possesses three major receptors, VAP-A, VAP-B and MOSPD2, which interact with proteins at the surface of other organelles to build contacts. VAP-A, VAP-B and MOSPD2 contain an MSP domain, which binds a motif named FFAT [two phenylalanines in an acidic tract]. In this study, we identified a non-conventional FFAT motif where a conserved acidic residue is replaced by a serine/threonine. We show that phosphorylation of this serine/threonine is critical for non-conventional FFAT motifs (named Phospho-FFAT) to be recognized by the MSP domain. Moreover, structural analyses of the MSP domain alone or in complex with conventional and Phospho-FFAT peptides revealed new mechanisms of interaction. Based on these new insights, we produced a novel prediction algorithm, which expands the repertoire of candidate proteins with a Phospho-FFAT that are able to create membrane contact sites. Using a prototypical tethering complex made by STARD3 and VAP, we showed that phosphorylation is instrumental for the formation of ER-endosome contacts, and their sterol transfer function. This study reveals that phosphorylation acts as a general switch for inter-organelle contacts.

SUBMITTER: Dr. Thomas Di Mattia

PROVIDER: S-SCDT-EMBOJ-2019-104369 | biostudies-other |

REPOSITORIES: biostudies-other

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FFAT motif phosphorylation controls formation and lipid transfer function of inter-organelle contacts.

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