Structure of a CGI-58 motif provides the molecular basis of lipid droplet anchoring.
Triacylglycerols (TGs) stored in lipid droplets (LDs) are hydrolyzed in a highly regulated metabolic process called lipolysis to free fatty acids that serve as energy substrates for β-oxidation, precursors for membrane lipids and signaling molecules. Comparative gene identification-58 (CGI-58) stimulates the enzymatic activity of adipose triglyceride lipase (ATGL), which catalyzes the hydrolysis of TGs to diacylglycerols and free fatty acids. In adipose tissue, protein-protein interactions between CGI-58 and the LD coating protein perilipin 1 restrain the ability of CGI-58 to activate ATGL under basal conditions. Phosphorylation of perilipin 1 disrupts these interactions and mobilizes CGI-58 for the activation of ATGL. We have previously demonstrated that the removal of a peptide at the N terminus (residues 10-31) of CGI-58 abrogates CGI-58 localization to LDs and CGI-58-mediated activation of ATGL. Here, we show that this tryptophan-rich N-terminal peptide serves as an independent LD anchor, with its three tryptophans serving as focal points of the left (harboring Trp(21) and Trp(25)) and right (harboring Trp(29)) anchor arms. The solution state NMR structure of a peptide comprising the LD anchor bound to dodecylphosphocholine micelles as LD mimic reveals that the left arm forms a concise hydrophobic core comprising tryptophans Trp(21) and Trp(25) and two adjacent leucines. Trp(29) serves as the core of a functionally independent anchor arm. Consequently, simultaneous tryptophan alanine permutations in both arms abolish localization and activity of CGI-58 as opposed to tryptophan substitutions that occur in only one arm.
From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria, the Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115.
Andras
A
Boeszoermenyi
From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria.
Harald Manuel
HM
Nagy
the Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115.
Haribabu
H
Arthanari
From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria.
Christoph Jens
CJ
Pillip
From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria, the Institute of Biophysics, Medical University of Graz, 8010 Graz, Austria.
Hanna
H
Lindermuth
the Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115.
Rafael Eulogio
RE
Luna
the Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115.
Gerhard
G
Wagner
From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria.
Rudolf
R
Zechner
the Institute of Chemistry, University of Graz, 8010 Graz, Austria, and.
Klaus
K
Zangger
From the Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria, m.oberer@uni-graz.at.
Monika
M
Oberer
D051103:1-Acylglycerol-3-Phosphate O-Acyltransferase / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D004789:Enzyme Activation; D006801:Humans; D008049:Lipase / Q000235:genetics / Q000378:metabolism*; D066292:Lipid Droplets / Q000378:metabolism*; D017384:Sequence Deletion; D014280:Triglycerides / Q000235:genetics / Q000378:metabolism; D000217:Acyltransferases
D051103:1-Acylglycerol-3-Phosphate O-Acyltransferase; D008049:Lipase; D014280:Triglycerides; C439972:ABHD5 protein, human; C494794:PNPLA2 protein, human; D000217:Acyltransferases
ABHD5; CGI-58; DPC; adipose triglyceride lipase (ATGL); lipid droplet; micelle; nuclear magnetic resonance (NMR); paramagnetic relaxation enhancement; peptide; peptides