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Li Y, Guo Y, Bröer A, Dai L, Brӧer S, Yan R. Cryo-EM structure of the human Asc-1 transporter complex. Nat Commun 2024; 15:3036. [PMID: 38589439 PMCID: PMC11001984 DOI: 10.1038/s41467-024-47468-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 04/02/2024] [Indexed: 04/10/2024] Open
Abstract
The Alanine-Serine-Cysteine transporter 1 (Asc-1 or SLC7A10) forms a crucial heterodimeric transporter complex with 4F2hc (SLC3A2) through a covalent disulfide bridge. This complex enables the sodium-independent transport of small neutral amino acids, including L-Alanine (L-Ala), Glycine (Gly), and D-Serine (D-Ser), within the central nervous system (CNS). D-Ser and Gly are two key endogenous glutamate co-agonists that activate N-methyl-d-aspartate (NMDA) receptors by binding to the allosteric site. Mice deficient in Asc-1 display severe symptoms such as tremors, ataxia, and seizures, leading to early postnatal death. Despite its physiological importance, the functional mechanism of the Asc-1-4F2hc complex has remained elusive. Here, we present cryo-electron microscopy (cryo-EM) structures of the human Asc-1-4F2hc complex in its apo state, D-Ser bound state, and L-Ala bound state, resolved at 3.6 Å, 3.5 Å, and 3.4 Å, respectively. Through detailed structural analysis and transport assays, we uncover a comprehensive alternating access mechanism that underlies conformational changes in the complex. In summary, our findings reveal the architecture of the Asc-1 and 4F2hc complex and provide valuable insights into substrate recognition and the functional cycle of this essential transporter complex.
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Affiliation(s)
- Yaning Li
- Department of Biochemistry, Key University Laboratory of Metabolism and Health of Guangdong, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong Province, China
- Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, Guangdong Province, China
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yingying Guo
- Department of Biochemistry, Key University Laboratory of Metabolism and Health of Guangdong, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong Province, China
| | - Angelika Bröer
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Lu Dai
- Department of Biochemistry, Key University Laboratory of Metabolism and Health of Guangdong, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong Province, China
| | - Stefan Brӧer
- Research School of Biology, Australian National University, Canberra, ACT, Australia.
| | - Renhong Yan
- Department of Biochemistry, Key University Laboratory of Metabolism and Health of Guangdong, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong Province, China.
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2
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Tang J, Long G, Hu K, Xiao D, Liu S, Xiao L, Zhou L, Tao Y. Targeting USP8 Inhibits O-GlcNAcylation of SLC7A11 to Promote Ferroptosis of Hepatocellular Carcinoma via Stabilization of OGT. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2302953. [PMID: 37867237 PMCID: PMC10667802 DOI: 10.1002/advs.202302953] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 09/10/2023] [Indexed: 10/24/2023]
Abstract
Hepatocellular carcinoma (HCC) is a lethal and aggressive human malignancy. The present study examins the anti-tumor effects of deubiquitylating enzymes (DUB) inhibitors in HCC. It is found that the inhibitor of ubiquitin specific peptidase 8 (USP8) and DUB-IN-3 shows the most effective anti-cancer responses. Targeting USP8 inhibits the proliferation of HCC and induces cell ferroptosis. In vivo xenograft and metastasis experiments indicate that inhibition of USP8 suppresses tumor growth and lung metastasis. DUB-IN-3 treatment or USP8 depletion decrease intracellular cystine levels and glutathione biosynthesis while increasing the accumulation of reactive oxygen species (ROS). Mechanistical studies reveal that USP8 stabilizes O-GlcNAc transferase (OGT) via inhibiting K48-specific poly-ubiquitination process on OGT protein at K117 site, and STE20-like kinase (SLK)-mediated S716 phosphorylation of USP8 is required for the interaction with OGT. Most importantly, OGT O-GlcNAcylates solute carrier family 7, member 11 (SLC7A11) at Ser26 in HCC cells, which is essential for SLC7A11 to import the cystine from the extracellular environment. Collectively, this study demonstrates that pharmacological inhibition or knockout of USP8 can inhibit the progression of HCC and induce ferroptosis via decreasing the stability of OGT, which imposes a great challenge that targeting of USP8 is a potential approach for HCC treatment.
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Affiliation(s)
- Jianing Tang
- Department of Liver SurgeryXiangya HospitalCentral South University110 Xiangya RoadChangshaHunan410078China
- National Clinical Research Center for Geriatric DisordersXiangya HospitalCentral South UniversityChangshaHunan410008China
| | - Guo Long
- Department of Liver SurgeryXiangya HospitalCentral South University110 Xiangya RoadChangshaHunan410078China
| | - Kuan Hu
- Department of Liver SurgeryXiangya HospitalCentral South University110 Xiangya RoadChangshaHunan410078China
| | - Desheng Xiao
- Department of PathologyXiangya HospitalCentral South UniversityChangshaHunan410078China
| | - Shuang Liu
- Department of OncologyInstitute of Medical SciencesNational Clinical Research Center for Geriatric DisordersXiangya HospitalCentral South UniversityChangshaHunan410078China
| | - Liang Xiao
- Department of Liver SurgeryXiangya HospitalCentral South University110 Xiangya RoadChangshaHunan410078China
| | - Ledu Zhou
- Department of Liver SurgeryXiangya HospitalCentral South University110 Xiangya RoadChangshaHunan410078China
| | - Yongguang Tao
- Department of PathologyKey Laboratory of Carcinogenesis and Cancer Invasion (Ministry of Education)Xiangya HospitalCentral South University110 Xiangya RoadChangshaHunan410078China
- NHC Key Laboratory of Carcinogenesis (Central South University)Cancer Research Institute and School of Basic MedicineCentral South University110 Xiangya RoadChangshaHunan410078China
- Department of Thoracic SurgeryHunan Key Laboratory of Early Diagnosis and Precision Therapy in Lung Cancer and Hunan Key Laboratory of Tumor Models and Individualized MedicineSecond Xiangya HospitalCentral South University110 Xiangya RoadChangshaHunan410011China
- Hunan Key Laboratory of Cancer MetabolismHunan Cancer Hospital and Affiliated Cancer Hospital of Xiangya School of MedicineCentral South University110 Xiangya RoadChangshaHunan410078China
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3
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Liu Y, Xiong H, Yan C, Wang Y, Cao W, Qie S. Bioinformatic Analysis of The Prognostic Value of A Panel of Six Amino Acid Transporters in Human Cancers. CELL JOURNAL 2023; 25:613-624. [PMID: 37718764 PMCID: PMC10520983 DOI: 10.22074/cellj.2023.2004011.1319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 07/05/2023] [Accepted: 08/06/2023] [Indexed: 09/19/2023]
Abstract
OBJECTIVE Solid tumor cells utilize amino acid transporters (AATs) to increase amino acid uptake in response to nutrient-insufficiency. The upregulation of AATs is therefore critical for tumor development and progression. This study identifies the upregulated AATs under amino acid deprived conditions, and further determines the clinicopathological importance of these AATs in evaluating the prognosis of patients with cancers. MATERIALS AND METHODS In this experimental study, the Gene Expression Omnibus (GEO) datasets (GSE62673, GSE26370, GSE125782 and GSE150874) were downloaded from the NCBI website and utilized for integrated differential expression and pathway analysis v0.96, Gene Set Enrichment Analysis (GSEA), and REACTOME analyses to identify the AATs upregulated in response to amino acid deprivation. In addition, The Cancer Genome Atlas (TCGA) datasets with prognostic information were assessed and employed to evaluate the association of identified AATs with patients' prognoses using SurvExpress analysis. RESULTS Using analysis of NCBI GEO data, this study shows that amino acid deprivation leads to the upregulation of six AAT genes; SLC3A2, SLC7A5, SLC7A1, SLC1A4, SLC7A11 and SLC1A5. GSEA and REACTOME analyses identified altered signaling in cells exposed to amino acid deprivation, such as pathways related to stress responses, the cell cycle and apoptosis. In addition, Principal Component Analysis showed these six AAT genes to be well divided into two distinct clusters in relation to TCGA tumor tissues versus normal counterparts. Finally, Log-Rank analysis confirmed the upregulation of this panel of six AAT genes is correlated with poor prognosis in patients with colorectal, esophageal, kidney and lung cancers. CONCLUSION The upregulation of a panel of six AATs is common in several human cancers and may provide a valuable diagnostic tool to evaluate the prognosis of patients with colorectal, esophageal, kidney and lung cancers.
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Affiliation(s)
- Yaqi Liu
- Department of Pathology, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
- National Clinical Research Center for Cancer, Tianjin, China
- Key Laboratory of Cancer Prevention and Therapy (Tianjin), Tianjin, China
- Tianjin's Clinical Research Center for Cancer, Tianjin, China
| | - Haijuan Xiong
- Department of Pathology, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
- National Clinical Research Center for Cancer, Tianjin, China
- Key Laboratory of Cancer Prevention and Therapy (Tianjin), Tianjin, China
- Tianjin's Clinical Research Center for Cancer, Tianjin, China
| | - Chenhui Yan
- Department of Pathology, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
- National Clinical Research Center for Cancer, Tianjin, China
- Key Laboratory of Cancer Prevention and Therapy (Tianjin), Tianjin, China
- Tianjin's Clinical Research Center for Cancer, Tianjin, China
| | - Yalei Wang
- Department of Pathology, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
- National Clinical Research Center for Cancer, Tianjin, China
- Key Laboratory of Cancer Prevention and Therapy (Tianjin), Tianjin, China
- Tianjin's Clinical Research Center for Cancer, Tianjin, China
| | - Wenfeng Cao
- Department of Pathology, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
- National Clinical Research Center for Cancer, Tianjin, China
- Key Laboratory of Cancer Prevention and Therapy (Tianjin), Tianjin, China
- Tianjin's Clinical Research Center for Cancer, Tianjin, China
| | - Shuo Qie
- Department of Pathology, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China.
- National Clinical Research Center for Cancer, Tianjin, China
- Key Laboratory of Cancer Prevention and Therapy (Tianjin), Tianjin, China
- Tianjin's Clinical Research Center for Cancer, Tianjin, China
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4
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Niitsu A, Sugita Y. Towards de novo design of transmembrane α-helical assemblies using structural modelling and molecular dynamics simulation. Phys Chem Chem Phys 2023; 25:3595-3606. [PMID: 36647771 DOI: 10.1039/d2cp03972a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Computational de novo protein design involves iterative processes consisting of amino acid sequence design, structural modelling and scoring, and design validation by synthesis and experimental characterisation. Recent advances in protein structure prediction and modelling methods have enabled the highly efficient and accurate design of water-soluble proteins. However, the design of membrane proteins remains a major challenge. To advance membrane protein design, considering the higher complexity of membrane protein folding, stability, and dynamic interactions between water, ions, lipids, and proteins is an important task. For introducing explicit solvents and membranes to these design methods, all-atom molecular dynamics (MD) simulations of designed proteins provide useful information that cannot be obtained experimentally. In this review, we first describe two major approaches to designing transmembrane α-helical assemblies, consensus and de novo design. We further illustrate recent MD studies of membrane protein folding related to protein design, as well as advanced treatments in molecular models and conformational sampling techniques in the simulations. Finally, we discuss the possibility to introduce MD simulations after the existing static modelling and screening of design decoys as an additional step for refinement of the design, which considers membrane protein folding dynamics and interactions with explicit membranes.
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Affiliation(s)
- Ai Niitsu
- Theoretical Molecular Science Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
| | - Yuji Sugita
- Theoretical Molecular Science Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. .,Computational Biophysics Research Team, RIKEN Center for Computational Science, 7-1-26 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.,Laboratory for Biomolecular Function Simulation, RIKEN Center for Biosystems Dynamics Research, 6-7-1 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
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Fang X, Ardehali H, Min J, Wang F. The molecular and metabolic landscape of iron and ferroptosis in cardiovascular disease. Nat Rev Cardiol 2023; 20:7-23. [PMID: 35788564 PMCID: PMC9252571 DOI: 10.1038/s41569-022-00735-4] [Citation(s) in RCA: 255] [Impact Index Per Article: 255.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/30/2022] [Indexed: 02/08/2023]
Abstract
The maintenance of iron homeostasis is essential for proper cardiac function. A growing body of evidence suggests that iron imbalance is the common denominator in many subtypes of cardiovascular disease. In the past 10 years, ferroptosis, an iron-dependent form of regulated cell death, has become increasingly recognized as an important process that mediates the pathogenesis and progression of numerous cardiovascular diseases, including atherosclerosis, drug-induced heart failure, myocardial ischaemia-reperfusion injury, sepsis-induced cardiomyopathy, arrhythmia and diabetic cardiomyopathy. Therefore, a thorough understanding of the mechanisms involved in the regulation of iron metabolism and ferroptosis in cardiomyocytes might lead to improvements in disease management. In this Review, we summarize the relationship between the metabolic and molecular pathways of iron signalling and ferroptosis in the context of cardiovascular disease. We also discuss the potential targets of ferroptosis in the treatment of cardiovascular disease and describe the current limitations and future directions of these novel treatment targets.
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Affiliation(s)
- Xuexian Fang
- grid.410595.c0000 0001 2230 9154Department of Nutrition and Toxicology, School of Public Health, State Key Laboratory of Experimental Hematology, Hangzhou Normal University, Hangzhou, China ,grid.13402.340000 0004 1759 700XThe Fourth Affiliated Hospital, The First Affiliated Hospital, Institute of Translational Medicine, School of Public Health, Cancer Center, State Key Laboratory of Experimental Hematology, Zhejiang University School of Medicine, Hangzhou, China ,grid.412017.10000 0001 0266 8918The First Affiliated Hospital, The Second Affiliated Hospital, Basic Medical Sciences, School of Public Health, Hengyang Medical School, University of South China, Hengyang, China
| | - Hossein Ardehali
- grid.16753.360000 0001 2299 3507Feinberg Cardiovascular and Renal Research Institute, Northwestern University, Chicago, IL USA
| | - Junxia Min
- The Fourth Affiliated Hospital, The First Affiliated Hospital, Institute of Translational Medicine, School of Public Health, Cancer Center, State Key Laboratory of Experimental Hematology, Zhejiang University School of Medicine, Hangzhou, China.
| | - Fudi Wang
- The Fourth Affiliated Hospital, The First Affiliated Hospital, Institute of Translational Medicine, School of Public Health, Cancer Center, State Key Laboratory of Experimental Hematology, Zhejiang University School of Medicine, Hangzhou, China. .,The First Affiliated Hospital, The Second Affiliated Hospital, Basic Medical Sciences, School of Public Health, Hengyang Medical School, University of South China, Hengyang, China.
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6
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Hang TD, Hung HM, Beckers P, Desmet N, Lamrani M, Massie A, Hermans E, Vanommeslaeghe K. Structural investigation of human cystine/glutamate antiporter system xc− (Sxc−) using homology modeling and molecular dynamics. Front Mol Biosci 2022; 9:1064199. [DOI: 10.3389/fmolb.2022.1064199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 11/15/2022] [Indexed: 12/04/2022] Open
Abstract
The cystine/glutamate antiporter system xc− (Sxc−) belongs to the SLC7 family of plasma membrane transporters. It exports intracellular glutamate along the latter’s concentration gradient as a driving force for cellular uptake of cystine. Once imported, cystine is mainly used for the production of glutathione, a tripeptide thiol crucial in maintenance of redox homeostasis and protection of cells against oxidative stress. Overexpression of Sxc− has been found in several cancer cells, where it is thought to counteract the increased oxidative stress. In addition, Sxc− is important in the central nervous system, playing a complex role in regulating glutamatergic neurotransmission and glutamate toxicity. Accordingly, this transporter is considered a potential target for the treatment of cancer as well as neurodegenerative diseases. Till now, no specific inhibitors are available. We herein present four conformations of Sxc− along its transport pathway, obtained using multi-template homology modeling and refined by means of Molecular Dynamics. Comparison with a very recently released cryo-EM structure revealed an excellent agreement with our inward-open conformation. Intriguingly, our models contain a structured N-terminal domain that is unresolved in the experimental structures and is thought to play a gating role in the transport mechanism of other SLC7 family members. In contrast to the inward-open model, there is no direct experimental counterpart for the other three conformations we obtained, although they are in fair agreement with the other stages of the transport mechanism seen in other SLC7 transporters. Therefore, our models open the prospect for targeting alternative Sxc− conformations in structure-based drug design efforts.
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Futamata H, Fukuda M, Umeda R, Yamashita K, Tomita A, Takahashi S, Shikakura T, Hayashi S, Kusakizako T, Nishizawa T, Homma K, Nureki O. Cryo-EM structures of thermostabilized prestin provide mechanistic insights underlying outer hair cell electromotility. Nat Commun 2022; 13:6208. [PMID: 36266333 PMCID: PMC9584906 DOI: 10.1038/s41467-022-34017-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 10/11/2022] [Indexed: 01/11/2023] Open
Abstract
Outer hair cell elecromotility, driven by prestin, is essential for mammalian cochlear amplification. Here, we report the cryo-EM structures of thermostabilized prestin (PresTS), complexed with chloride, sulfate, or salicylate at 3.52-3.63 Å resolutions. The central positively-charged cavity allows flexible binding of various anion species, which likely accounts for the known distinct modulations of nonlinear capacitance (NLC) by different anions. Comparisons of these PresTS structures with recent prestin structures suggest rigid-body movement between the core and gate domains, and provide mechanistic insights into prestin inhibition by salicylate. Mutations at the dimeric interface severely diminished NLC, suggesting that stabilization of the gate domain facilitates core domain movement, thereby contributing to the expression of NLC. These findings advance our understanding of the molecular mechanism underlying mammalian cochlear amplification.
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Affiliation(s)
- Haon Futamata
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Masahiro Fukuda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo; Meguro-ku, Tokyo, 153-8503, Japan
| | - Rie Umeda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Keitaro Yamashita
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Atsuhiro Tomita
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Satoe Takahashi
- Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Takafumi Shikakura
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa, Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Shigehiko Hayashi
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa, Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Tsukasa Kusakizako
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Tomohiro Nishizawa
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.
- Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan.
| | - Kazuaki Homma
- Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA.
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, IL, 60608, USA.
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.
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Galluccio M, Scalise M, Pappacoda G, Scarpelli M, Bonanomi M, Gaglio D, Indiveri C. Production of recombinant human xCT (SLC7A11) and reconstitution in proteoliposomes for functional studies. Front Physiol 2022; 13:993626. [PMID: 36148304 PMCID: PMC9485625 DOI: 10.3389/fphys.2022.993626] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 08/16/2022] [Indexed: 11/13/2022] Open
Abstract
The plasma membrane transporter xCT belongs to the SLC7 family and has the physiological role of mediating the exchange of glutamate and cystine across the cell plasma membrane, being crucial for redox control. The xCT protein forms a heterodimer with the ancillary protein CD98. Over the years, xCT became a hot pharmacological target due to the documented over-expression in virtually all human cancers, which rely on cystine availability for their progression. Notwithstanding, several unknown aspects of xCT biology still exist that require a suitable single protein experimental model, to be addressed. To this aim, the recombinant host Escherichia coli has been exploited to over-express the human isoform of xCT. In this widely used and low-cost system, the optimization for growth and protein production has been achieved by acting on the metabolic needs of the bacterial strains. Then, the His-tagged protein has been purified by Ni2+-chelating chromatography and reconstituted in proteoliposomes for transport activity assays. The expressed protein was in a folded/active state allowing functional and kinetic characterization. Interestingly, the features of the recombinant protein meet those of the native one extracted from intact cells, further confirming the suitability of E. coli as a host for the expression of human proteins. This study opens perspectives for elucidating other molecular aspects of xCT, as well as for studying the interaction with endogenous and exogenous compounds, relevant to human health.
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Affiliation(s)
- Michele Galluccio
- Unit of Biochemistry and Molecular Biotechnology, Department DiBEST (Biologia Ecologia Scienze della Terra), University of Calabria, Arcavacata di Rende, Italy
| | - Mariafrancesca Scalise
- Unit of Biochemistry and Molecular Biotechnology, Department DiBEST (Biologia Ecologia Scienze della Terra), University of Calabria, Arcavacata di Rende, Italy
| | - Gilda Pappacoda
- Unit of Biochemistry and Molecular Biotechnology, Department DiBEST (Biologia Ecologia Scienze della Terra), University of Calabria, Arcavacata di Rende, Italy
| | - Martina Scarpelli
- Unit of Biochemistry and Molecular Biotechnology, Department DiBEST (Biologia Ecologia Scienze della Terra), University of Calabria, Arcavacata di Rende, Italy
| | - Marcella Bonanomi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
- ISBE.IT/Centre of Systems Biology, Milan, Italy
| | - Daniela Gaglio
- ISBE.IT/Centre of Systems Biology, Milan, Italy
- Institute of Molecular Bioimaging and Physiology (IBFM), National Research Council (CNR), Milan, Italy
| | - Cesare Indiveri
- Unit of Biochemistry and Molecular Biotechnology, Department DiBEST (Biologia Ecologia Scienze della Terra), University of Calabria, Arcavacata di Rende, Italy
- CNR Institute of Biomembranes, Bioenergetics, and Molecular Biotechnologies (IBIOM), Bari, Italy
- *Correspondence: Cesare Indiveri,
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9
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Romero ML, Garcia Seisdedos H, Ibarra‐Molero B. Active site center redesign increases protein stability preserving catalysis in thioredoxin. Protein Sci 2022. [PMCID: PMC9601870 DOI: 10.1002/pro.4417] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The stabilization of natural proteins is a long‐standing desired goal in protein engineering. Optimizing the hydrophobicity of the protein core often results in extensive stability enhancements. However, the presence of totally or partially buried catalytic charged residues, essential for protein function, has limited the applicability of this strategy. Here, focusing on the thioredoxin, we aimed to augment protein stability by removing buried charged residues in the active site without loss of catalytic activity. To this end, we performed a charged‐to‐hydrophobic substitution of a buried and functional group, resulting in a significant stability increase yet abolishing catalytic activity. Then, to simulate the catalytic role of the buried ionizable group, we designed a combinatorial library of variants targeting a set of seven surface residues adjacent to the active site. Notably, more than 50% of the library variants restored, to some extent, the catalytic activity. The combination of experimental study of 2% of the library with the prediction of the whole mutational space by partial least squares regression revealed that a single point mutation at the protein surface is sufficient to fully restore the catalytic activity without thermostability cost. As a result, we engineered one of the highest thermal stabilities reported for a protein with a natural occurring fold (137°C). Further, our hyperstable variant preserves the catalytic activity both in vitro and in vivo.
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Affiliation(s)
- Maria Luisa Romero
- Departamento de Química Física Universidad de Granada Granada
- Max Planck Institute of Molecular Cell Biology and Genetics Dresden Germany
- Center for Systems Biology Dresden Dresden Germany
| | - Hector Garcia Seisdedos
- Departamento de Química Física Universidad de Granada Granada
- Department of Structural Biology Weizmann Institute of Science Rehovot Israel
- Department of Structural Biology Instituto de Biologia Molecular de Barcelona (IBMB‐CSIC) Barcelona Spain
| | - Beatriz Ibarra‐Molero
- Departamento de Química Física Universidad de Granada Granada
- Department of Structural Biology Instituto de Biologia Molecular de Barcelona (IBMB‐CSIC) Barcelona Spain
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SLC7A11/GPX4 Inactivation-Mediated Ferroptosis Contributes to the Pathogenesis of Triptolide-Induced Cardiotoxicity. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:3192607. [PMID: 35757509 PMCID: PMC9225845 DOI: 10.1155/2022/3192607] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 05/16/2022] [Accepted: 05/18/2022] [Indexed: 12/18/2022]
Abstract
Triptolide exhibits promising efficacy in various cancers and immune diseases while its clinical application has been strongly restricted by its severe side effects, especially cardiotoxicity. However, the underlying mechanism of triptolide-induced cardiotoxicity (TIC) remains unclear. The RNA-seq analysis of triptolide-injured AC16 human cardiomyocyte cell line hinted that ferroptosis is involved in TIC. Further experimental validations proved that triptolide triggered ferroptosis, as evidenced by significant accumulation of lipid peroxidation (4-HNE and MDA levels) and ferrous iron, as well as depletion of intracellular GSH. Furthermore, triptolide-induced iron overload involved the upregulation of TF/TRFC/DMT1 signal axis and the degradation of ferritin, which contribute to ROS generation via Fenton reaction. In addition, inhibition of the antioxidant Nrf2/HO-1 pathway was observed in TIC, which may also lead to the overproduction of lethal lipid peroxides. Mechanistically, using streptavidin-biotin affinity pull-down assay and computational molecular docking, we unveiled that triptolide directly binds to SLC7A11 to inactivate SLC7A11/GPX4 signal axis. More importantly, employment of a ferroptosis inhibitor Ferrostatin-1 alleviated TIC by partially reversing the inhibitory effects of triptolide on SLC7A11/GPX4 signal. Altogether, our study demonstrated that SLC7A11/GPX4 inactivation-mediated ferroptosis contributed to the pathogenesis of TIC. Combating ferroptosis may be a promising therapeutic avenue to prevent TIC.
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11
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The structure of erastin-bound xCT-4F2hc complex reveals molecular mechanisms underlying erastin-induced ferroptosis. Cell Res 2022; 32:687-690. [PMID: 35352032 PMCID: PMC9253326 DOI: 10.1038/s41422-022-00642-w] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 02/23/2022] [Indexed: 02/08/2023] Open
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12
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Parker JL, Deme JC, Kolokouris D, Kuteyi G, Biggin PC, Lea SM, Newstead S. Molecular basis for redox control by the human cystine/glutamate antiporter system xc . Nat Commun 2021; 12:7147. [PMID: 34880232 PMCID: PMC8654953 DOI: 10.1038/s41467-021-27414-1] [Citation(s) in RCA: 73] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 11/17/2021] [Indexed: 12/13/2022] Open
Abstract
Cysteine plays an essential role in cellular redox homoeostasis as a key constituent of the tripeptide glutathione (GSH). A rate limiting step in cellular GSH synthesis is the availability of cysteine. However, circulating cysteine exists in the blood as the oxidised di-peptide cystine, requiring specialised transport systems for its import into the cell. System xc- is a dedicated cystine transporter, importing cystine in exchange for intracellular glutamate. To counteract elevated levels of reactive oxygen species in cancerous cells system xc- is frequently upregulated, making it an attractive target for anticancer therapies. However, the molecular basis for ligand recognition remains elusive, hampering efforts to specifically target this transport system. Here we present the cryo-EM structure of system xc- in both the apo and glutamate bound states. Structural comparisons reveal an allosteric mechanism for ligand discrimination, supported by molecular dynamics and cell-based assays, establishing a mechanism for cystine transport in human cells.
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Affiliation(s)
- Joanne L Parker
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK.
| | - Justin C Deme
- Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
- Central Oxford Structural Molecular Imaging Centre, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | | | - Gabriel Kuteyi
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Philip C Biggin
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Susan M Lea
- Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK.
- Central Oxford Structural Molecular Imaging Centre, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK.
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA.
| | - Simon Newstead
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK.
- The Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, OX1 3QU, UK.
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13
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Fort J, Nicolàs-Aragó A, Palacín M. The Ectodomains of rBAT and 4F2hc Are Fake or Orphan α-Glucosidases. Molecules 2021; 26:6231. [PMID: 34684812 PMCID: PMC8537225 DOI: 10.3390/molecules26206231] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/11/2021] [Accepted: 10/12/2021] [Indexed: 11/22/2022] Open
Abstract
It is known that 4F2hc and rBAT are the heavy subunits of the heteromeric amino acid transporters (HATs). These heavy subunits are N-glycosylated proteins, with an N-terminal domain, one transmembrane domain and a bulky extracellular domain (ectodomain) that belongs to the α-amylase family. The heavy subunits are covalently linked to a light subunit from the SLC7 family, which is responsible for the amino acid transport activity, forming a heterodimer. The functions of 4F2hc and rBAT are related mainly to the stability and trafficking of the HATs in the plasma membrane of vertebrates, where they exert the transport activity. Moreover, 4F2hc is a modulator of integrin signaling, has a role in cell fusion and it is overexpressed in some types of cancers. On the other hand, some mutations in rBAT are found to cause the malfunctioning of the b0,+ transport system, leading to cystinuria. The ectodomains of 4F2hc and rBAT share both sequence and structure homology with α-amylase family members. Very recently, cryo-EM has revealed the structure of several HATs, including the ectodomains of rBAT and 4F2hc. Here, we analyze available data on the ectodomains of rBAT and 4Fhc and their relationship with the α-amylase family. The physiological relevance of this relationship remains largely unknown.
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Affiliation(s)
- Joana Fort
- Laboratory of Amino Acid Transporters and Disease, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028 Barcelona, Spain; (A.N.-A.); (M.P.)
- CIBERER (Centro Español en Red de Biomedicina de Enfermedades Raras), 08028 Barcelona, Spain
- Department of Biochemistry and Molecular Biomedicine, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Adrià Nicolàs-Aragó
- Laboratory of Amino Acid Transporters and Disease, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028 Barcelona, Spain; (A.N.-A.); (M.P.)
| | - Manuel Palacín
- Laboratory of Amino Acid Transporters and Disease, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028 Barcelona, Spain; (A.N.-A.); (M.P.)
- CIBERER (Centro Español en Red de Biomedicina de Enfermedades Raras), 08028 Barcelona, Spain
- Department of Biochemistry and Molecular Biomedicine, Universitat de Barcelona, 08028 Barcelona, Spain
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14
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Nicolàs-Aragó A, Fort J, Palacín M, Errasti-Murugarren E. Rush Hour of LATs towards Their Transport Cycle. MEMBRANES 2021; 11:602. [PMID: 34436365 PMCID: PMC8399266 DOI: 10.3390/membranes11080602] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/03/2021] [Accepted: 08/04/2021] [Indexed: 12/29/2022]
Abstract
The mammalian SLC7 family comprises the L-amino acid transporters (LATs) and the cationic amino acid transporters (CATs). The relevance of these transporters is highlighted by their involvement in several human pathologies, including inherited rare diseases and acquired diseases, such as cancer. In the last four years, several crystal or cryo-EM structures of LATs and CATs have been solved. These structures have started to fill our knowledge gap that previously was based on the structural biology of remote homologs of the amino acid-polyamine-organocation (APC) transporters. This review recovers this structural and functional information to start generating the molecular bases of the transport cycle of LATs. Special attention is given to the known transporter conformations within the transport cycle and the molecular bases for substrate interaction and translocation, including the asymmetric interaction of substrates at both sides of the plasma membrane.
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Affiliation(s)
- Adrià Nicolàs-Aragó
- Laboratory of Amino Acid Transporters and Disease, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028 Barcelona, Spain; (A.N.-A.); (J.F.)
| | - Joana Fort
- Laboratory of Amino Acid Transporters and Disease, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028 Barcelona, Spain; (A.N.-A.); (J.F.)
- CIBERER (Centro Español en Red de Biomedicina de Enfermedades Raras), 08028 Barcelona, Spain
- Department of Biochemistry and Molecular Biomedicine, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Manuel Palacín
- Laboratory of Amino Acid Transporters and Disease, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028 Barcelona, Spain; (A.N.-A.); (J.F.)
- CIBERER (Centro Español en Red de Biomedicina de Enfermedades Raras), 08028 Barcelona, Spain
- Department of Biochemistry and Molecular Biomedicine, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Ekaitz Errasti-Murugarren
- Laboratory of Amino Acid Transporters and Disease, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028 Barcelona, Spain; (A.N.-A.); (J.F.)
- CIBERER (Centro Español en Red de Biomedicina de Enfermedades Raras), 08028 Barcelona, Spain
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15
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Pichia pastoris and the Recombinant Human Heterodimeric Amino Acid Transporter 4F2hc-LAT1: From Clone Selection to Pure Protein. Methods Protoc 2021; 4:mps4030051. [PMID: 34449687 PMCID: PMC8396027 DOI: 10.3390/mps4030051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/20/2021] [Accepted: 07/21/2021] [Indexed: 12/12/2022] Open
Abstract
Heterodimeric amino acid transporters (HATs) are protein complexes composed of two subunits, a heavy and a light subunit belonging to the solute carrier (SLC) families SLC3 and SLC7. HATs transport amino acids and derivatives thereof across the plasma membrane. The human HAT 4F2hc-LAT1 is composed of the type-II membrane N-glycoprotein 4F2hc (SLC3A2) and the L-type amino acid transporter LAT1 (SLC7A5). 4F2hc-LAT1 is medically relevant, and its dysfunction and overexpression are associated with autism and tumor progression. Here, we provide a general applicable protocol on how to screen for the best membrane transport protein-expressing clone in terms of protein amount and function using Pichia pastoris as expression host. Furthermore, we describe an overexpression and purification procedure for the production of the HAT 4F2hc-LAT1. The isolated heterodimeric complex is pure, correctly assembled, stable, binds the substrate L-leucine, and is thus properly folded. Therefore, this Pichia pastoris-derived recombinant human 4F2hc-LAT1 sample can be used for downstream biochemical and biophysical characterizations.
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16
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Saito Y, Soga T. Amino acid transporters as emerging therapeutic targets in cancer. Cancer Sci 2021; 112:2958-2965. [PMID: 34091991 PMCID: PMC8353895 DOI: 10.1111/cas.15006] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/13/2021] [Accepted: 05/31/2021] [Indexed: 01/17/2023] Open
Abstract
Amino acids are indispensable nutrients for both normal and cancer cells. Cancer cells are unable to synthesize essential amino acids as well as some non‐essential amino acids adequately to support rapid proliferation, and must take up amino acids from the surroundings. To meet the increased demand for the amino acid needed for proliferation, high levels of amino acid transporters are expressed on the surface of cancer cells. Cancer cells utilize amino acids to synthesize proteins and nucleotides, as well as to obtain energy. In addition, amino acids are known to play pathological roles in cancer cells. Interestingly, breast cancer cells limit the use of amino acids for cell proliferation based on amino acid availability, which depends on estrogen receptor status. Here, we present a summarized literature review of novel amino acid functions in cancer cells. This review organizes the available knowledge on 2 amino acid transporters, SLC7A5 and SLC7A11, which are considered essential for breast cancer cell growth in a cell‐dependent manner. In particular, we propose the glutamine recycling model to clarify the mechanism underlying aberrant SLC7A5 activation. Finally, we overview the pathological significances of SLC7A5 and SLC7A11 in cancer tissues.
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Affiliation(s)
- Yasuhiro Saito
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan
| | - Tomoyoshi Soga
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan
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17
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Errasti-Murugarren E, Bartoccioni P, Palacín M. Membrane Protein Stabilization Strategies for Structural and Functional Studies. MEMBRANES 2021; 11:membranes11020155. [PMID: 33671740 PMCID: PMC7926488 DOI: 10.3390/membranes11020155] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 02/15/2021] [Accepted: 02/18/2021] [Indexed: 02/07/2023]
Abstract
Accounting for nearly two-thirds of known druggable targets, membrane proteins are highly relevant for cell physiology and pharmacology. In this regard, the structural determination of pharmacologically relevant targets would facilitate the intelligent design of new drugs. The structural biology of membrane proteins is a field experiencing significant growth as a result of the development of new strategies for structure determination. However, membrane protein preparation for structural studies continues to be a limiting step in many cases due to the inherent instability of these molecules in non-native membrane environments. This review describes the approaches that have been developed to improve membrane protein stability. Membrane protein mutagenesis, detergent selection, lipid membrane mimics, antibodies, and ligands are described in this review as approaches to facilitate the production of purified and stable membrane proteins of interest for structural and functional studies.
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Affiliation(s)
- Ekaitz Errasti-Murugarren
- Laboratory of Amino acid Transporters and Disease, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028 Barcelona, Spain;
- CIBERER (Centro Español en Red de Biomedicina de Enfermedades Raras), 28029 Barcelona, Spain
- Correspondence: (E.E.-M.); (M.P.)
| | - Paola Bartoccioni
- Laboratory of Amino acid Transporters and Disease, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028 Barcelona, Spain;
- CIBERER (Centro Español en Red de Biomedicina de Enfermedades Raras), 28029 Barcelona, Spain
| | - Manuel Palacín
- Laboratory of Amino acid Transporters and Disease, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028 Barcelona, Spain;
- CIBERER (Centro Español en Red de Biomedicina de Enfermedades Raras), 28029 Barcelona, Spain
- Department of Biochemistry and Molecular Biomedicine, Universitat de Barcelona, 08028 Barcelona, Spain
- Correspondence: (E.E.-M.); (M.P.)
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18
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Cormerais Y, Vučetić M, Parks SK, Pouyssegur J. Amino Acid Transporters Are a Vital Focal Point in the Control of mTORC1 Signaling and Cancer. Int J Mol Sci 2020; 22:E23. [PMID: 33375025 PMCID: PMC7792758 DOI: 10.3390/ijms22010023] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 11/26/2020] [Accepted: 11/27/2020] [Indexed: 12/14/2022] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) integrates signals from growth factors and nutrients to control biosynthetic processes, including protein, lipid, and nucleic acid synthesis. Dysregulation in the mTORC1 network underlies a wide array of pathological states, including metabolic diseases, neurological disorders, and cancer. Tumor cells are characterized by uncontrolled growth and proliferation due to a reduced dependency on exogenous growth factors. The genetic events underlying this property, such as mutations in the PI3K-Akt and Ras-Erk signaling networks, lead to constitutive activation of mTORC1 in nearly all human cancer lineages. Aberrant activation of mTORC1 has been shown to play a key role for both anabolic tumor growth and resistance to targeted therapeutics. While displaying a growth factor-independent mTORC1 activity and proliferation, tumors cells remain dependent on exogenous nutrients such as amino acids (AAs). AAs are an essential class of nutrients that are obligatory for the survival of any cell. Known as the building blocks of proteins, AAs also act as essential metabolites for numerous biosynthetic processes such as fatty acids, membrane lipids and nucleotides synthesis, as well as for maintaining redox homeostasis. In most tumor types, mTORC1 activity is particularly sensitive to intracellular AA levels. This dependency, therefore, creates a targetable vulnerability point as cancer cells become dependent on AA transporters to sustain their homeostasis. The following review will discuss the role of AA transporters for mTORC1 signaling in cancer cells and their potential as therapeutic drug targets.
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Affiliation(s)
- Yann Cormerais
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Milica Vučetić
- Department of Medical Biology, Centre Scientifique de Monaco (CSM), 98000 Monaco, Monaco; (M.V.); (S.K.P.)
| | - Scott K. Parks
- Department of Medical Biology, Centre Scientifique de Monaco (CSM), 98000 Monaco, Monaco; (M.V.); (S.K.P.)
| | - Jacques Pouyssegur
- Department of Medical Biology, Centre Scientifique de Monaco (CSM), 98000 Monaco, Monaco; (M.V.); (S.K.P.)
- CNRS, INSERM, Centre A. Lacassagne, Faculté de Médecine (IRCAN), Université Côte d’Azur, 06107 Nice, France
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Oda K, Lee Y, Wiriyasermkul P, Tanaka Y, Takemoto M, Yamashita K, Nagamori S, Nishizawa T, Nureki O. Consensus mutagenesis approach improves the thermal stability of system x c - transporter, xCT, and enables cryo-EM analyses. Protein Sci 2020; 29:2398-2407. [PMID: 33016372 PMCID: PMC7679960 DOI: 10.1002/pro.3966] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 09/26/2020] [Accepted: 09/29/2020] [Indexed: 12/20/2022]
Abstract
System xc− is an amino acid antiporter that imports L‐cystine into cells and exports intracellular L‐glutamate, at a 1:1 ratio. As L‐cystine is an essential precursor for glutathione synthesis, system xc− supports tumor cell growth through glutathione‐based oxidative stress resistance and is considered as a potential therapeutic target for cancer treatment. System xc− consists of two subunits, the light chain subunit SLC7A11 (xCT) and the heavy chain subunit SLC3A2 (also known as CD98hc or 4F2hc), which are linked by a conserved disulfide bridge. Although the recent structures of another SLC7 member, L‐type amino acid transporter 1 (LAT1) in complex with CD98hc, have provided the structural basis toward understanding the amino acid transport mechanism, the detailed molecular mechanism of xCT remains unknown. To revealthe molecular mechanism, we performed single‐particle analyses of the xCT‐CD98hc complex. As wild‐type xCT‐CD98hc displayed poor stability and could not be purified to homogeneity, we applied a consensus mutagenesis approach to xCT. The consensus mutated construct exhibited increased stability as compared to the wild‐type, and enabled the cryoelectron microscopy (cryo‐EM) map to be obtained at 6.2 Å resolution by single‐particle analysis. The cryo‐EM map revealed sufficient electron density to assign secondary structures. In the xCT structure, the hash and arm domains are well resolved, whereas the bundle domain shows some flexibility. CD98hc is positioned next to the xCT transmembrane domain. This study provides the structural basis of xCT, and our consensus‐based strategy could represent a good choice toward solving unstable protein structures.
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Affiliation(s)
- Kazumasa Oda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Yongchan Lee
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Pattama Wiriyasermkul
- Department of Collaborative Research for Bio-Molecular Dynamics, Nara Medical University, Nara, Japan
| | - Yoko Tanaka
- Department of Collaborative Research for Bio-Molecular Dynamics, Nara Medical University, Nara, Japan
| | - Mizuki Takemoto
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Keitaro Yamashita
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Shushi Nagamori
- Department of Collaborative Research for Bio-Molecular Dynamics, Nara Medical University, Nara, Japan
| | - Tomohiro Nishizawa
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
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