期刊
PLANT PHYSIOLOGY
卷 175, 期 2, 页码 667-680出版社
AMER SOC PLANT BIOLOGISTS
DOI: 10.1104/pp.17.00934
关键词
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资金
- Canada Research Chairs
- Natural Sciences and Engineering Research Council of Canada (NSERC) [RGPIN-2015-05163, RGPIN-2016-06478, RGPIN-2014-04585]
- Alberta Innovates Bio Solutions
- Deutsche Forschungsgemeinschaft of the International Research Training Group 1830
- Alberta Innovates Health Solutions Scholar Program
- Alberta Innovates Technology Futures Graduate Scholarship
- Alberta Canola Producers Commission Graduate Award
- NSERC-International Research Training Group in Membrane Biology Postdoctoral Fellowship
- Canadian Foundation for Innovation
- Alberta Innovates [201500143] Funding Source: researchfish
Diacylglycerol acyltransferase 1 (DGAT1) is an integral membrane enzyme catalyzing the final and committed step in the acylcoenzyme 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 Brassica napus DGAT1 (BnaDGAT11-113) 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 a-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.
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