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Yang B, Yao H, Li D, Liu Z. The phosphatidylglycerol phosphate synthase PgsA utilizes a trifurcated amphipathic cavity for catalysis at the membrane-cytosol interface. Curr Res Struct Biol 2021; 3:312-323. [PMID: 34901881 PMCID: PMC8640168 DOI: 10.1016/j.crstbi.2021.11.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 10/24/2021] [Accepted: 11/17/2021] [Indexed: 12/26/2022] Open
Abstract
Phosphatidylglycerol is a crucial phospholipid found ubiquitously in biological membranes of prokaryotic and eukaryotic cells. The phosphatidylglycerol phosphate (PGP) synthase (PgsA), a membrane-embedded enzyme, catalyzes the primary reaction of phosphatidylglycerol biosynthesis. Mutations in pgsA frequently correlate with daptomycin resistance in Staphylococcus aureus and other prevalent infectious pathogens. Here we report the crystal structures of S. aureus PgsA (SaPgsA) captured at two distinct states of the catalytic process, with lipid substrate (cytidine diphosphate-diacylglycerol, CDP-DAG) or product (PGP) bound to the active site within a trifurcated amphipathic cavity. The hydrophilic head groups of CDP-DAG and PGP occupy two different pockets in the cavity, inducing local conformational changes. An elongated membrane-exposed surface groove accommodates the fatty acyl chains of CDP-DAG/PGP and opens a lateral portal for lipid entry/release. Remarkably, the daptomycin resistance-related mutations mostly cluster around the active site, causing reduction of enzymatic activity. Our results provide detailed mechanistic insights into the dynamic catalytic process of PgsA and structural frameworks beneficial for development of antimicrobial agents targeting PgsA from pathogenic bacteria. PgsA uses a trifurcated amphipathic cavity for binding of substrates or products. Conversion of CDP-DAG to PGP induces local conformational changes in PgsA. Daptomycin-resistant mutations of PgsA mostly lead to reduced catalytic activity. A structure-based five-state model is proposed for the synthesis of PGP by PgsA.
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Affiliation(s)
- Bowei Yang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hebang Yao
- CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, 201210, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Dianfan Li
- CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, 201210, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhenfeng Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
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Lan Y, Bai P, Chen Z, Neelamegam R, Placzek MS, Wang H, Fiedler SA, Yang J, Yuan G, Qu X, Schmidt HR, Song J, Normandin MD, Ran C, Wang C. Novel radioligands for imaging sigma-1 receptor in brain using positron emission tomography (PET). Acta Pharm Sin B 2019; 9:1204-1215. [PMID: 31867166 PMCID: PMC6900558 DOI: 10.1016/j.apsb.2019.07.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Revised: 06/28/2019] [Accepted: 07/04/2019] [Indexed: 12/18/2022] Open
Abstract
The sigma-1 receptor (σ1R) is a unique intracellular protein. σ1R plays a major role in various pathological conditions in the central nervous system (CNS), implicated in several neuropsychiatric disorders. Imaging of σ1R in the brain using positron emission tomography (PET) could serve as a noninvasively tool for enhancing the understanding of the disease's pathophysiology. Moreover, σ1R PET tracers can be used for target validation and quantification in diagnosis. Herein, we describe the radiosynthesis, in vivo PET/CT imaging of novel σ1R 11C-labeled radioligands based on 6-hydroxypyridazinone, [11C]HCC0923 and [11C]HCC0929. Two radioligands have high affinities to σ1R, with good selectivity. In mice PET/CT imaging, both radioligands showed appropriate kinetics and distributions. Additionally, the specific interactions of two radioligands were reduced by compounds 13 and 15 (self-blocking). Of the two, [11C]HCC0929 was further investigated in positive ligands blocking studies, using classic σ1R agonist SA 4503 and σ1R antagonist PD 144418. Both σ1R ligands could extensively decreased the uptake of [11C]HCC0929 in mice brain. Besides, the biodistribution of major brain regions and organs of mice were determined in vivo. These studies demonstrated that two radioligands, especially [11C]HCC0929, possessed ideal imaging properties and might be valuable tools for non-invasive quantification of σ1R in brain.
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Key Words
- 11C-labeled radioligand
- 3D, three-dimensional
- 6-Hydroxypyridazinone
- AF, ammonium formate
- BBB, brain blood barrier
- BP, binding potential
- Brain imaging
- CNS, center nervous systems
- CRPS, complex regional pain syndrome
- DMF, dimethyl formamide
- DMSO, dimethylsulfoxide
- ER, endoplasmic reticulum
- LCP, lipidic cubic phase
- MAM, mitochondria-associated ER membrane
- PCP, phencyclidine
- PET
- PET, positron emission tomography
- TFA, trifluoroacetic acid
- σ1R
- σ1R, sigma-1 receptor
- σ2R, sigma-2 receptor
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