Structure and catalytic mechanism of a human triacylglycerol-synthesis enzyme

Sui, Xuewu; Wang, Kun; Gluchowski, Nina L.; Elliott, Shane D.; Liao, Maofu; Walther, Tobias C.; Farese, Robert V.

doi:10.1038/s41586-020-2289-6

Cited by 98 publications

(118 citation statements)

References 47 publications

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“…Therefore, seipin may initially attract TAG molecules in the ER bilayer and foster TAG aggregates to grow into a nascent LD. This is in line with the recently reported DGAT1 structure placing the active TAG-generating site within the ER bilayer (Sui et al., 2020; Wang et al., 2020). In the absence of seipin, efficient TAG phase separation in the ER would be delayed, leading to an increase in the ER TAG concentration, as reported (Cartwright et al., 2015; Gao et al., 2017).…”

Section: Seipin May Sequester Tags At Ld Formation Sitessupporting

confidence: 92%

Seipin-Mediated Contacts as Gatekeepers of Lipid Flux at the Endoplasmic Reticulum–Lipid Droplet Nexus

Salo

Hölttä‐Vuori

Ikonen

2020

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Lipid droplets (LDs) are dynamic cellular hubs of lipid metabolism. While LDs contact a plethora of organelles, they have the most intimate relationship with the endoplasmic reticulum (ER). Indeed, LDs are initially assembled at specialized ER subdomains, and recent work has unraveled an increasing array of proteins regulating ER-LD contacts. Among these, seipin, a highly conserved lipodystrophy protein critical for LD growth and adipogenesis, deserves special attention. Here, we review recent insights into the role of seipin in LD biogenesis and as a regulator of ER-LD contacts. These studies have also highlighted the evolving concept of ER and LDs as a functional continuum for lipid partitioning and pinpointed a role for seipin at the ER-LD nexus in controlling lipid flux between these compartments.

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Section: Seipin May Sequester Tags At Ld Formation Sitessupporting

confidence: 92%

Seipin-Mediated Contacts as Gatekeepers of Lipid Flux at the Endoplasmic Reticulum–Lipid Droplet Nexus

Salo

Hölttä‐Vuori

Ikonen

2020

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“…A possible physiological explanation for the asymmetric distribution of SURF-TG between the luminal leaflet and cytosolic leaflet of the ER bilayer can be found in the recently resolved structure of DGAT1. [92][93] Catalyzing the last step of TG synthesis, DGAT1 intakes DAG and outputs TG. The lateral gate, which is located closer to the luminal leaflet, is anticipated to be a pathway for the flow of the reactant and product.…”

Section: Discussionmentioning

confidence: 99%

Physical Characterization of Triolein and Implications for Its Role in Lipid Droplet Biogenesis

Kim

Voth

2021

Preprint

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Lipid droplets (LDs) are neutral lipid storing organelles surrounded by a phospholipid (PL) monolayer. At present, how LDs are formed in the endoplasmic reticulum (ER) bilayer is poorly understood. In this study, we present a revised triolein (TG) model, the main constituent of the LD core, and characterize its properties in a bilayer membrane to demonstrate the implications of its behavior in LD biogenesis. In all-atom (AA) bilayer simulations, TG resides at the surface, adopting PL-like conformations (denoted in this work as SURF-TG). Free energy sampling simulation results estimate the barrier for TG relocating from the bilayer surface to the bilayer center to be ~2 kcal/mol in the absence of an oil lens. Conical SURF-TG is able to modulate membrane properties by increasing PL ordering, decreasing bending modulus, and creating local negative curvature. The other conical lipid, dioleoyl-glycerol (DAG), also reduces the membrane bending modulus and populates the negative curvature regions. A phenomenological coarse-grained (CG) model is also developed to observe larger scale SURF-TG-mediated membrane deformation. The CG simulations confirm that TG nucleates between the bilayer leaflets at a critical concentration when SURF-TG is evenly distributed. However, when one monolayer contains more SURF-TG, the membrane bends toward the other leaflet. The central conclusion of this study is that SURF-TG is a negative curvature inducer, as well as a membrane modulator. To this end, a model has proposed in which the accumulation of SURF-TG in the luminal leaflet bends the ER bilayer toward the cytosolic side, followed by TG nucleation.

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“…Wei et al (2017) detected that NoDGAT1A expression in C. reinhardtii UVM4 had no effect on TAG accumulation under nitrogen-replete condition but TAG enhancement was observed under nitrogen-depleted condition has been detected using AutoDock [64,65]. However, compare to the presence of cryo-electron microscopy structure of human DGAT1 in complex with an oleoyl-CoA substrate [66,67], the absence 3D structures of DGAT2s hampers the accuracy of AudoDock results.…”

Section: Discussionmentioning

confidence: 99%

Characterization of type-2 diacylglycerol acyltransferases in Haematococcus lacustris reveals their functions and engineering potential in triacylglycerol biosynthesis and possible roles in astaxanthin esterification

Cui¹,

Zhao²,

Xu³

et al. 2020

Preprint

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Background: Haematococcus lacustris is an ideal source of astaxanthin (AST) which is stored at oil bodies containing esterified AST (EAST) and triacylglycerol (TAG). Diacylglycerol acyltransferases (DGATs) catalyze the last step of the acyl-CoA-dependent TAG biosynthesis and are also considered as the crucial enzymes involving in EAST biosynthesis in H. lacustris. Previous studies have identified four putative DGAT2 encoding genes in H. lacustris and only the HpDGAT2D allowed the recovery of TAG biosynthesis, but the engineering potential of HpDGAT2s in TAG biosynthesis, especially possible roles in AST esterification, remains ambiguous.Results: Five putative DGAT2 genes (HpDGAT2A, 2B, 2C, 2D, and 2E) were identified in H. lacustris. Transcription analysis showed that the expression levels of HpDGAT2A, 2B, and 2E genes markedly increased under high light and nitrogen deficient conditions with distinct patterns, which led to significant TAG and EAST accumulation. Functional complementation demonstrated HpDGAT2A, 2B, 2D, and 2E had the capability to restore TAG synthesis in a TAG-deficient yeast strain (H1246) with the large difference in enzymatic activity. Fatty acids (FAs) profiles assays revealed that HpDGAT2A, 2D, and 2E except for 2B preferred monounsaturated fatty acyl-CoA (MUFA) for TAG synthesis in yeast cells, and also showed polyunsaturated fatty acyl-CoA (PUFA) preference by feeding strategy. The over-expression of HpDGAT2D in Arabidopsis thaliana and Chlamydomonas reinhardtii significantly increased the TAG content and obviously promoted the MUFA and PUFA contents. Interestingly, molecular docking analysis implied that HpDGAT2s structures contained AST binding sites, which provides strong evidence for AST esterification function in H. lacustris.Conclusions: Our study represents a pioneering work on the characterization of HpDGAT2s by systematically integrating expression pattern, AST/TAG accumulation, functional complementation, molecular docking, and over-expression in yeast, plants, and algae. These results (1) update the gene models of HpDGAT2s, (2) prove TAG biosynthesis capacity of HpDGAT2s, (3) show the strong preference for MUFA and PUFA, (4) offer target genes to modulate TAG biosynthesis by genetic engineering method, and (5) provide new evidence for HpDGAT2s roles in AST esterification.

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Structure and catalytic mechanism of a human triacylglycerol-synthesis enzyme

Cited by 98 publications

References 47 publications

Seipin-Mediated Contacts as Gatekeepers of Lipid Flux at the Endoplasmic Reticulum–Lipid Droplet Nexus

Seipin-Mediated Contacts as Gatekeepers of Lipid Flux at the Endoplasmic Reticulum–Lipid Droplet Nexus

Physical Characterization of Triolein and Implications for Its Role in Lipid Droplet Biogenesis

Characterization of type-2 diacylglycerol acyltransferases in Haematococcus lacustris reveals their functions and engineering potential in triacylglycerol biosynthesis and possible roles in astaxanthin esterification

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