5UZL

Brassica napus DGAT1 exosite

Summary for 5UZL

• Entry DOI: 10.2210/pdb5uzl/pdb
• NMR Information: BMRB: 30256
• Descriptor: O-acyltransferase (1 entity in total)
• Functional Keywords: o-acyltransferase, transferase
• Biological source: Brassica napus (Rape)
• Cellular location: Endoplasmic reticulum membrane ; Multi-pass membrane protein : A0A078JH28
• Total number of polymer chains: 1
• Total formula weight: 3877.33

Authors

Acedo, J.Z.,Vederas, J.C. (deposition date: 2017-02-26, release date: 2018-01-03, Last modification date: 2024-05-15)

Primary citation

Caldo, K.M.P.,Acedo, J.Z.,Panigrahi, R.,Vederas, J.C.,Weselake, R.J.,Lemieux, M.J.
Diacylglycerol Acyltransferase 1 Is Regulated by Its N-Terminal Domain in Response to Allosteric Effectors.
Plant Physiol., 175:667-680, 2017

PubMed Abstract: Diacylglycerol acyltransferase 1 (DGAT1) is an integral membrane enzyme catalyzing the final and committed step in the acyl-coenzyme A (CoA)-dependent biosynthesis of triacylglycerol (TAG). The biochemical regulation of TAG assembly remains one of the least understood areas of primary metabolism to date. Here, we report that the hydrophilic N-terminal domain of DGAT1 (BnaDGAT1) regulates activity based on acyl-CoA/CoA levels. The N-terminal domain is not necessary for acyltransferase activity and is composed of an intrinsically disordered region and a folded segment. We show that the disordered region has an autoinhibitory function and a dimerization interface, which appears to mediate positive cooperativity, whereas the folded segment of the cytosolic region was found to have an allosteric site for acyl-CoA/CoA. Under increasing acyl-CoA levels, the binding of acyl-CoA with this noncatalytic site facilitates homotropic allosteric activation. Enzyme activation, on the other hand, is prevented under limiting acyl-CoA conditions (low acyl-CoA-to-CoA ratio), whereby CoA acts as a noncompetitive feedback inhibitor through interaction with the same folded segment. The three-dimensional NMR solution structure of the allosteric site revealed an α-helix with a loop connecting a coil fragment. The conserved amino acid residues in the loop interacting with CoA were identified, revealing details of this important regulatory element for allosteric regulation. Based on these results, a model is proposed illustrating the role of the N-terminal domain of BnaDGAT1 as a positive and negative modulator of TAG biosynthesis.

PubMed: 28827454
DOI: 10.1104/pp.17.00934

Experimental method

SOLUTION NMR