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Phospholipid transfer function of PTPIP51 at mitochondria-associated ER membranes

ABSTRACT: In eukaryotic cells, mitochondria are closely tethered to the endoplasmic reticulum (ER) at sites called mitochondria-associated ER membranes (MAMs). Ca2+ ion and phospholipid transfer occurs at MAMs to support diverse cellular functions. Unlike those in yeast, the protein complexes involved in phospholipid transfer at MAMs in humans have not been identified. Here, we determined the crystal structure of the tetratricopeptide repeat domain of PTPIP51 (PTPIP51_TPR), a mitochondrial protein that interacts with the ER-anchored VAPB protein at MAMs. The structure of PTPIP51_TPR showed an archetypal TPR fold, and an electron density corresponding to an unidentified lipid-like molecule probably derived from the protein expression host was found in the structure. We revealed functions of PTPIP51 in phospholipid binding/transfer, particularly of phosphatidic acid, in vitro. Depletion of PTPIP51 in cells reduced the mitochondrial cardiolipin level. Additionally, we confirmed that the PTPIP51–VAPB interaction is mediated by the FFAT-like motif of PTPIP51 and the MSP domain of VAPB. Our findings suggest that PTPIP51 is a phospholipid transfer protein with a MAM-tethering function similar to the ERMES complex in yeast.

ORGANISM(S): Human Homo Sapiens

TISSUE(S): Hela Cells

SUBMITTER: Jueun Lee

PROVIDER: ST001717 | MetabolomicsWorkbench | Thu Mar 04 00:00:00 GMT 2021

REPOSITORIES: MetabolomicsWorkbench

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