Dataset Information

New Crystallographic Snapshots of Large Domain Movements in Bacterial 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase.

ABSTRACT: The enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (HMGR) catalyzes the first committed step of the mevalonate pathway, which is used across biology in the biosynthesis of countless metabolites. HMGR consumes 2 equiv of the cofactor NAD(P)H to perform the four-electron reduction of HMG-CoA to mevalonate toward the production of steroids and isoprenoids, the largest class of natural products. Recent structural data have shown that HMGR contains a highly mobile C-terminal domain (CTD) that is believed to adopt many different conformations to permit binding and dissociation of the substrate, cofactors, and products at specific points during the reaction cycle. Here, we have characterized the HMGR from Delftia acidovorans as an NADH-specific enzyme and determined crystal structures of the enzyme in unbound, mevalonate-bound, and NADH- and citrate-bound states. Together, these structures depict ligand binding in both the active site and the cofactor-binding site while illustrating how a conserved helical motif confers NAD(P)H cofactor specificity. Unexpectedly, the NADH-bound structure also reveals a new conformation of the CTD, in which the domain has "flipped" upside-down, while directly binding the cofactor. By capturing these structural snapshots, this work not only expands the known range of HMGR domain movement but also provides valuable insight into the catalytic mechanism of this biologically important enzyme.

SUBMITTER: Ragwan ER

PROVIDER: S-EPMC6319916 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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New Crystallographic Snapshots of Large Domain Movements in Bacterial 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase.

Ragwan Edwin R ER Arai Eri E Kung Yan Y

Biochemistry 20180919 39

The enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (HMGR) catalyzes the first committed step of the mevalonate pathway, which is used across biology in the biosynthesis of countless metabolites. HMGR consumes 2 equiv of the cofactor NAD(P)H to perform the four-electron reduction of HMG-CoA to mevalonate toward the production of steroids and isoprenoids, the largest class of natural products. Recent structural data have shown that HMGR contains a highly mobile C-terminal domain ...[more]

PMID: 30199631

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Project description:In addition to inducing a self-limited myopathy, statin use is associated with an immune-mediated necrotizing myopathy (IMNM), with autoantibodies that recognize ?200-kd and ?100-kd autoantigens. The purpose of this study was to identify these molecules to help clarify the disease mechanism and facilitate diagnosis.The effect of statin treatment on autoantigen expression was addressed by immunoprecipitation using sera from patients. The identity of the ?100-kd autoantigen was confirmed by immunoprecipitation of in vitro-translated 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) protein. HMGCR expression in muscle was analyzed by immunofluorescence. A cohort of myopathy patients was screened for anti-HMGCR autoantibodies by enzyme-linked immunosorbent assay and genotyped for the rs4149056 C allele, a predictor of self-limited statin myopathy.Statin exposure induced expression of the ?200-kd/?100-kd autoantigens in cultured cells. HMGCR was identified as the ?100-kd autoantigen. Competition experiments demonstrated no distinct autoantibodies recognizing the ?200-kd protein. In muscle biopsy tissues from anti-HMGCR-positive patients, HMGCR expression was up-regulated in cells expressing neural cell adhesion molecule, a marker of muscle regeneration. Anti-HMGCR autoantibodies were found in 45 of 750 patients presenting to the Johns Hopkins Myositis Center (6%). Among patients ages 50 years and older, 92.3% had taken statins. The prevalence of the rs4149056 C allele was not increased in patients with anti-HMGCR.Statins up-regulate the expression of HMGCR, the major target of autoantibodies in statin-associated IMNM. Regenerating muscle cells express high levels of HMGCR, which may sustain the immune response even after statins are discontinued. These studies demonstrate a mechanistic link between an environmental trigger and the development of sustained autoimmunity. Detection of anti-HMGCR autoantibodies may facilitate diagnosis and direct therapy.

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Dataset Information

New Crystallographic Snapshots of Large Domain Movements in Bacterial 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase.

Publications

New Crystallographic Snapshots of Large Domain Movements in Bacterial 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase.

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