Deconstructing the DGAT1 Enzyme: Membrane Interactions at Substrate Binding Sites

Author(s)

Lopes, Jose L. S. ^[1] ; Beltramini, Leila M. ^[1] ; Wallace, Bonnie A. ^[2] ; Araujo, Ana P. U. ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Fis Sao Carlos, Sao Carlos, SP - Brazil

^[2] Univ London, Birkbeck Coll, Inst Struct & Mol Biol, London - England

• Document type: Journal article
• Source: PLoS One; v. 10, n. 2 FEB 26 2015.
• Web of Science Citations: 8

Abstract

Diacylglycerol acyltransferase 1 (DGAT1) is a key enzyme in the triacylglyceride synthesis pathway. Bovine DGAT1 is an endoplasmic reticulum membrane-bound protein associated with the regulation of fat content in milk and meat. The aim of this study was to evaluate the interaction of DGAT1 peptides corresponding to putative substrate binding sites with different types of model membranes. Whilst these peptides are predicted to be located in an extramembranous loop of the membrane-bound protein, their hydrophobic substrates are membrane-bound molecules. In this study, peptides corresponding to the binding sites of the two substrates involved in the reaction were examined in the presence of model membranes in order to probe potential interactions between them that might influence the subsequent binding of the substrates. Whilst the conformation of one of the peptides changed upon binding several types of micelles regardless of their surface charge, suggesting binding to hydrophobic domains, the other peptide bound strongly to negatively-charged model membranes. This binding was accompanied by a change in conformation, and produced leakage of the liposome-entrapped dye calcein. The different hydrophobic and electrostatic interactions observed suggest the peptides may be involved in the interactions of the enzyme with membrane surfaces, facilitating access of the catalytic histidine to the triacylglycerol substrates. (AU)

• FAPESP's process: 09/17698-5 - Structural investigation of the bovine enzyme diacylglyceroltransferase1 (DGAT1) and its interaction with lipid systems
• Grantee: Jose Luiz de Souza Lopes
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 10/13036-5 - Study of the interaction between internal peptides from the bovine diacylglycerol acyltransferase 1 (DGAT1) and membrane models
• Grantee: Nádia de Cássia Noronha
• Support Opportunities: Scholarships in Brazil - Scientific Initiation