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Dual binding motifs underpin the hierarchical association of perilipins1-3 with lipid droplets.

Accepted version
Peer-reviewed

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Authors

Ajjaji, Dalila 
Ben M'barek, Kalthoum 
Mimmack, Michael L 
England, Cheryl 
Herscovitz, Haya 

Abstract

Lipid droplets (LDs) in all eukaryotic cells are coated with at least one of the perilipin (Plin) family of proteins. They all regulate key intracellular lipases but do so to significantly different extents. Where more than one Plin is expressed in a cell, they associate with LDs in a hierarchical manner. In vivo, this means that lipid flux control in a particular cell or tissue type is heavily influenced by the specific Plins present on its LDs. Despite their early discovery, exactly how Plins target LDs and why they displace each other in a "hierarchical" manner remains unclear. They all share an amino-terminal 11-mer repeat (11mr) amphipathic region suggested to be involved in LD targeting. Here, we show that, in vivo, this domain functions as a primary highly reversible LD targeting motif in Plin1-3, and, in vitro, we document reversible and competitive binding between a wild-type purified Plin1 11mr peptide and a mutant with reduced binding affinity to both "naked" and phospholipid-coated oil-water interfaces. We also present data suggesting that a second carboxy-terminal 4-helix bundle domain stabilizes LD binding in Plin1 more effectively than in Plin2, whereas it weakens binding in Plin3. These findings suggest that dual amphipathic helical regions mediate LD targeting and underpin the hierarchical binding of Plin1-3 to LDs.

Description

Keywords

Amino Acid Motifs, Cell Line, Tumor, Humans, Lipid Droplets, Mutant Proteins, Oils, Perilipins, Phospholipids, Protein Binding, Protein Domains, Water

Journal Title

Mol Biol Cell

Conference Name

Journal ISSN

1059-1524
1939-4586

Volume Title

30

Publisher

American Society for Cell Biology (ASCB)
Sponsorship
Wellcome Trust (107064/Z/15/Z)
Cambridge University Hospitals NHS Foundation Trust (CUH) (146281)
Medical Research Council (MC_UU_12012/1)
Medical Research Council (MC_UU_12012/5)
MRC (MC_UU_00014/5)
Medical Research Council (MC_PC_12012)