7OXP

Cryo-EM structure of yeast Sei1

This is a non-PDB format compatible entry.

Summary for 7OXP

• Entry DOI: 10.2210/pdb7oxp/pdb
• EMDB information: 13103
• Descriptor: BJ4_G0032880.mRNA.1.CDS.1,BJ4_G0032880.mRNA.1.CDS.1 (1 entity in total)
• Functional Keywords: lipid droplet formation, lipid binding, seipin, membrane protein
• Biological source: Saccharomyces cerevisiae (Baker's yeast); More
• Total number of polymer chains: 10
• Total formula weight: 366641.25

Authors

Deme, J.C.,Lea, S.M. (deposition date: 2021-06-22, release date: 2021-10-13, Last modification date: 2021-10-20)

Primary citation

Klug, Y.A.,Deme, J.C.,Corey, R.A.,Renne, M.F.,Stansfeld, P.J.,Lea, S.M.,Carvalho, P.
Mechanism of lipid droplet formation by the yeast Sei1/Ldb16 Seipin complex.
Nat Commun, 12:5892-5892, 2021

PubMed Abstract: Lipid droplets (LDs) are universal lipid storage organelles with a core of neutral lipids, such as triacylglycerols, surrounded by a phospholipid monolayer. This unique architecture is generated during LD biogenesis at endoplasmic reticulum (ER) sites marked by Seipin, a conserved membrane protein mutated in lipodystrophy. Here structural, biochemical and molecular dynamics simulation approaches reveal the mechanism of LD formation by the yeast Seipin Sei1 and its membrane partner Ldb16. We show that Sei1 luminal domain assembles a homooligomeric ring, which, in contrast to other Seipins, is unable to concentrate triacylglycerol. Instead, Sei1 positions Ldb16, which concentrates triacylglycerol within the Sei1 ring through critical hydroxyl residues. Triacylglycerol recruitment to the complex is further promoted by Sei1 transmembrane segments, which also control Ldb16 stability. Thus, we propose that LD assembly by the Sei1/Ldb16 complex, and likely other Seipins, requires sequential triacylglycerol-concentrating steps via distinct elements in the ER membrane and lumen.

PubMed: 34625558
DOI: 10.1038/s41467-021-26162-6

Experimental method

ELECTRON MICROSCOPY (2.7 Å)