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Kumar R, Mendonca J, Shetty A, Yang Y, Owoyemi O, Wilson L, Boyapati K, Topiwala D, Thomas N, Nguyen H, Luo J, Paller CJ, Denmeade S, Carducci MA, Kachhap SK. CRM1 regulates androgen receptor stability and impacts DNA repair pathways in prostate cancer, independent of the androgen receptor. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.13.579966. [PMID: 38405771 PMCID: PMC10888881 DOI: 10.1101/2024.02.13.579966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Among the known nuclear exportins, CRM1 is the most studied prototype. Dysregulation of CRM1 occurs in many cancers, hence, understanding the role of CRM1 in cancer can help in developing synergistic therapeutics. The study investigates how CRM1 affects prostate cancer growth and survival. It examines the role of CRM1 in regulating androgen receptor (AR) and DNA repair in prostate cancer. Our findings reveal that CRM1 influences AR mRNA and protein stability, leading to a loss of AR protein upon CRM1 inhibition. Furthermore, it highlights the involvement of HSP90 alpha, a known AR chaperone, in the CRM1-dependent regulation of AR protein stability. The combination of CRM1 inhibition with an HSP90 inhibitor demonstrates potent effects on decreasing prostate cancer cell growth and survival. The study further explores the influence of CRM1 on DNA repair proteins and proposes a strategy of combining CRM1 inhibitors with DNA repair pathway inhibitors to decrease prostate cancer growth. Overall, the findings suggest that CRM1 plays a crucial role in prostate cancer growth, and a combination of inhibitors targeting CRM1 and DNA repair pathways could be a promising therapeutic strategy.
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2
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Tian J, Dewer Y, Qu C, Li F, Luo C. Heat-shock protein 70-a hub gene-underwent adaptive evolution involved in whitefly-wild tomato interaction. PEST MANAGEMENT SCIENCE 2022; 78:4471-4479. [PMID: 35796079 DOI: 10.1002/ps.7065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 06/29/2022] [Accepted: 07/07/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND The whitefly Bemisia tabaci causes severe damage to cultivated tomato plants, but actively avoids the wild tomato Solanum habrochaites. Moreover, the mortality of whitefly increases significantly after feeding with the wild tomato. However, additional experiments are warranted to more carefully elucidate the specific molecular elements underlying the interaction between whitefly and wild tomato. RESULTS Our results showed that S. habrochaites significantly increases the mortality of whitefly adults and decreases both their fertility and fecundity. In addition, the expression of stress-response genes in whitefly after exposure to S. habrochaites was analyzed using RNA sequencing. Weighted gene co-expression network analysis was conducted to identify the hub genes to determine their potential associations with the mortality of whitefly. These results suggested that the expression of heat-shock protein (HSP), multicopper oxidase, and 2-Oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline (OHCU) decarboxylase genes were induced in whitefly. To validate the gene associations with whitefly mortality, a high-throughput in vivo model system and RNAi-based gene silencing were used. The results revealed that the RNAi-mediated depletion of the HSP gene, which belongs to the HSP70 subfamily, increased the mortality of whitefly. Furthermore, the selection pressure analysis showed that a total of five amino acid sites of positive selection were identified, three of which were located in the nucleotide-binding domain and the other two in the substrate-binding domain. CONCLUSIONS This is the first report on the potential implication of HSPs in whitefly-wild plant interactions. This study could more precisely identify the molecular mechanisms of whitefly in response to wild tomatoes. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Jiahui Tian
- Beijing Key Laboratory of Environment Friendly Management on Fruit Diseases and Pests in North China, Institute of Plant and Environment Protection, Beijing Academy of Agriculture and Forestry Sciences, Beijing, China
| | - Youssef Dewer
- Phytotoxicity Research Department, Central Agricultural Pesticide Laboratory, Agricultural Research Center, Giza, Egypt
| | - Cheng Qu
- Beijing Key Laboratory of Environment Friendly Management on Fruit Diseases and Pests in North China, Institute of Plant and Environment Protection, Beijing Academy of Agriculture and Forestry Sciences, Beijing, China
| | - Fengqi Li
- Beijing Key Laboratory of Environment Friendly Management on Fruit Diseases and Pests in North China, Institute of Plant and Environment Protection, Beijing Academy of Agriculture and Forestry Sciences, Beijing, China
| | - Chen Luo
- Beijing Key Laboratory of Environment Friendly Management on Fruit Diseases and Pests in North China, Institute of Plant and Environment Protection, Beijing Academy of Agriculture and Forestry Sciences, Beijing, China
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3
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Dong XM, Zhao K, Zheng WW, Xu CW, Zhang MJ, Yin RH, Gao R, Tang LJ, Liu JF, Chen H, Zhan YQ, Yu M, Ge CH, Gao HY, Li X, Luo T, Ning HM, Yang XM, Li CY. EDAG mediates Hsp70 nuclear localization in erythroblasts and rescues dyserythropoiesis in myelodysplastic syndrome. FASEB J 2020; 34:8416-8427. [PMID: 32350948 DOI: 10.1096/fj.201902946r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 04/06/2020] [Accepted: 04/13/2020] [Indexed: 12/11/2022]
Abstract
During human erythroid maturation, Hsp70 translocates into the nucleus and protects GATA-1 from caspase-3 cleavage. Failure of Hsp70 to localize to the nucleus was found in Myelodysplastic syndrome (MDS) erythroblasts and can induce dyserythropoiesis, with arrest of maturation and death of erythroblasts. However, the mechanism of the nuclear trafficking of Hsp70 in erythroblasts remains unknown. Here, we found the hematopoietic transcriptional regulator, EDAG, to be a novel binding partner of Hsp70 that forms a protein complex with Hsp70 and GATA-1 during human normal erythroid differentiation. EDAG overexpression blocked the cytoplasmic translocation of Hsp70 induced by EPO deprivation, inhibited GATA-1 degradation, thereby promoting erythroid maturation in an Hsp70-dependent manner. Furthermore, in myelodysplastic syndrome (MDS) patients with dyserythropoiesis, EDAG is dramatically down-regulated, and forced expression of EDAG has been found to restore the localization of Hsp70 in the nucleus and elevate the protein level of GATA-1 to a significant extent. In addition, EDAG rescued the dyserythropoiesis of MDS patients by increasing erythroid differentiation and decreasing cell apoptosis. This study demonstrates the molecular mechanism of Hsp70 nuclear sustaining during erythroid maturation and establishes that EDAG might be a suitable therapeutic target for dyserythropoiesis in MDS patients.
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Affiliation(s)
- Xiao-Ming Dong
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing, China.,Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China.,College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Ke Zhao
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing, China
| | - Wei-Wei Zheng
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing, China
| | - Cheng-Wang Xu
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing, China
| | - Mei-Jiang Zhang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing, China.,Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Rong-Hua Yin
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing, China
| | - Rui Gao
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing, China
| | - Liu-Jun Tang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing, China
| | - Jin-Fang Liu
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing, China
| | - Hui Chen
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing, China
| | - Yi-Qun Zhan
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing, China
| | - Miao Yu
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing, China
| | - Chang-Hui Ge
- Department of Experimental Hematology and Biochemistry, Beijing Institute of Radiation Medicine, Beijing, China
| | - Hui-Ying Gao
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing, China
| | - Xiu Li
- School of Postgraduate, Anhui Medical University, Hefei, China
| | - Teng Luo
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing, China
| | - Hong-Mei Ning
- Department of Hematopoietic Stem Cell Transplantation, The Fifth Medical Center of Chinese PLA General Hospital, Beijing, China
| | - Xiao-Ming Yang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing, China.,Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China.,School of Postgraduate, Anhui Medical University, Hefei, China
| | - Chang-Yan Li
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Lifeomics, Beijing, China.,School of Postgraduate, Anhui Medical University, Hefei, China
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4
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Cafe SL, Nixon B, Dun MD, Roman SD, Bernstein IR, Bromfield EG. Oxidative Stress Dysregulates Protein Homeostasis Within the Male Germ Line. Antioxid Redox Signal 2020; 32:487-503. [PMID: 31830800 DOI: 10.1089/ars.2019.7832] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Aims: Oxidative stress is causally linked to male reproductive pathologies, driven primarily by lipid peroxidation and an attendant production of highly reactive lipid aldehydes, such as 4-hydroxynonenal (4HNE) within the male germ line. In somatic cells, 4HNE dysregulates proteostasis via targeting of vulnerable proteins for adduction, causing protein misfolding and eventually aggregation. The aims of this study were to explore whether oxidative stress precipitates an equivalent response in the male germ line and determine the protective mechanisms used by germ cells to prevent this cascade of protein damage. Results: We reveal a causative role for oxidative stress in the accumulation of protein deposits in male germ cells. Specifically, 4HNE treatment resulted in a significant increase in cytosolic protein aggregation within pre- and post-meiotic germ cells as measured by the aggregate-detecting fluorophores ProteoStat and Thioflavin T, and the amyloid-specific anti-A11 and anti-OC antibodies. Our data implicate nucleocytoplasmic transport machinery and molecular chaperones as potential mechanisms for the subcellular compartmentalization and/or suppression of aggregating proteins. Thus, the inhibition of karyopherin transport proteins and molecular chaperones resulted in a significant increase in the accumulation of aggregated cellular protein. Innovation: These data establish the novel paradigm that lipid peroxidation is a key contributor to a decline in proteostasis in developing germ cells. These findings will inform the development of novel strategies to protect germ cells from oxidative stress. Conclusion: Together, these results shed light on proteostasis mechanisms that may assist in the management of misfolded proteins in the male germ line under conditions of acute oxidative stress.
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Affiliation(s)
- Shenae Louise Cafe
- Priority Research Centre for Reproductive Science, School of Environmental and Life Sciences, Discipline of Biological Sciences, University of Newcastle, Callaghan, Australia
| | - Brett Nixon
- Priority Research Centre for Reproductive Science, School of Environmental and Life Sciences, Discipline of Biological Sciences, University of Newcastle, Callaghan, Australia
| | - Matthew D Dun
- Cancer Signaling Research Group, School of Biomedical Sciences, Faculty of Health and Medicine, University of Newcastle, Callaghan, Australia.,Priority Research Centre for Cancer Research Innovation and Translation, Hunter Medical Research Institute, Lambton, Australia
| | - Shaun Daryl Roman
- Priority Research Centre for Reproductive Science, School of Environmental and Life Sciences, Discipline of Biological Sciences, University of Newcastle, Callaghan, Australia.,Priority Research Centre for Drug Development, School of Environmental and Life Sciences, Discipline of Biological Sciences, University of Newcastle, Callaghan, Australia
| | - Ilana Ruth Bernstein
- Priority Research Centre for Reproductive Science, School of Environmental and Life Sciences, Discipline of Biological Sciences, University of Newcastle, Callaghan, Australia
| | - Elizabeth Grace Bromfield
- Priority Research Centre for Reproductive Science, School of Environmental and Life Sciences, Discipline of Biological Sciences, University of Newcastle, Callaghan, Australia.,Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
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5
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Gribling-Burrer AS, Chiabudini M, Zhang Y, Qiu Z, Scazzari M, Wölfle T, Wohlwend D, Rospert S. A dual role of the ribosome-bound chaperones RAC/Ssb in maintaining the fidelity of translation termination. Nucleic Acids Res 2020; 47:7018-7034. [PMID: 31114879 PMCID: PMC6648330 DOI: 10.1093/nar/gkz334] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 04/05/2019] [Accepted: 04/25/2019] [Indexed: 11/22/2022] Open
Abstract
The yeast ribosome-associated complex RAC and the Hsp70 homolog Ssb are anchored to the ribosome and together act as chaperones for the folding and co-translational assembly of nascent polypeptides. In addition, the RAC/Ssb system plays a crucial role in maintaining the fidelity of translation termination; however, the latter function is poorly understood. Here we show that the RAC/Ssb system promotes the fidelity of translation termination via two distinct mechanisms. First, via direct contacts with the ribosome and the nascent chain, RAC/Ssb facilitates the translation of stalling-prone poly-AAG/A sequences encoding for polylysine segments. Impairment of this function leads to enhanced ribosome stalling and to premature nascent polypeptide release at AAG/A codons. Second, RAC/Ssb is required for the assembly of fully functional ribosomes. When RAC/Ssb is absent, ribosome biogenesis is hampered such that core ribosomal particles are structurally altered at the decoding and peptidyl transferase centers. As a result, ribosomes assembled in the absence of RAC/Ssb bind to the aminoglycoside paromomycin with high affinity (KD = 76.6 nM) and display impaired discrimination between stop codons and sense codons. The combined data shed light on the multiple mechanisms by which the RAC/Ssb system promotes unimpeded biogenesis of newly synthesized polypeptides.
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Affiliation(s)
- Anne-Sophie Gribling-Burrer
- Institute of Biochemistry and Molecular Biology, ZBMZ, Medical Faculty, University of Freiburg, D-79104 Freiburg, Germany
| | - Marco Chiabudini
- Institute of Biochemistry and Molecular Biology, ZBMZ, Medical Faculty, University of Freiburg, D-79104 Freiburg, Germany
| | - Ying Zhang
- Institute of Biochemistry and Molecular Biology, ZBMZ, Medical Faculty, University of Freiburg, D-79104 Freiburg, Germany
| | - Zonghao Qiu
- Institute of Biochemistry and Molecular Biology, ZBMZ, Medical Faculty, University of Freiburg, D-79104 Freiburg, Germany
| | - Mario Scazzari
- Institute of Biochemistry and Molecular Biology, ZBMZ, Medical Faculty, University of Freiburg, D-79104 Freiburg, Germany
| | - Tina Wölfle
- Institute of Biochemistry and Molecular Biology, ZBMZ, Medical Faculty, University of Freiburg, D-79104 Freiburg, Germany
| | - Daniel Wohlwend
- Institute of Biochemistry, Chemical and Pharmaceutical Faculty, University of Freiburg, D-79104 Freiburg, Germany
| | - Sabine Rospert
- Institute of Biochemistry and Molecular Biology, ZBMZ, Medical Faculty, University of Freiburg, D-79104 Freiburg, Germany.,BIOSS Centre for Biological Signaling Studies, University of Freiburg, D-79104 Freiburg, Germany
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6
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Deuerling E, Gamerdinger M, Kreft SG. Chaperone Interactions at the Ribosome. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a033977. [PMID: 30833456 DOI: 10.1101/cshperspect.a033977] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The continuous refreshment of the proteome is critical to maintain protein homeostasis and to adapt cells to changing conditions. Thus, de novo protein biogenesis by ribosomes is vitally important to every cellular system. This process is delicate and error-prone and requires, besides cytosolic chaperones, the guidance by a specialized set of molecular chaperones that bind transiently to the translation machinery and the nascent protein to support early folding events and to regulate cotranslational protein transport. These chaperones include the bacterial trigger factor (TF), the archaeal and eukaryotic nascent polypeptide-associated complex (NAC), and the eukaryotic ribosome-associated complex (RAC). This review focuses on the structures, functions, and substrates of these ribosome-associated chaperones and highlights the most recent findings about their potential mechanisms of action.
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Affiliation(s)
- Elke Deuerling
- Molecular Microbiology, Department of Biology, University of Konstanz, 78464 Konstanz, Germany
| | - Martin Gamerdinger
- Molecular Microbiology, Department of Biology, University of Konstanz, 78464 Konstanz, Germany
| | - Stefan G Kreft
- Molecular Microbiology, Department of Biology, University of Konstanz, 78464 Konstanz, Germany
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7
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Rempel IL, Crane MM, Thaller DJ, Mishra A, Jansen DP, Janssens G, Popken P, Akşit A, Kaeberlein M, van der Giessen E, Steen A, Onck PR, Lusk CP, Veenhoff LM. Age-dependent deterioration of nuclear pore assembly in mitotic cells decreases transport dynamics. eLife 2019; 8:48186. [PMID: 31157618 PMCID: PMC6579512 DOI: 10.7554/elife.48186] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 06/02/2019] [Indexed: 12/28/2022] Open
Abstract
Nuclear transport is facilitated by the Nuclear Pore Complex (NPC) and is essential for life in eukaryotes. The NPC is a long-lived and exceptionally large structure. We asked whether NPC quality control is compromised in aging mitotic cells. Our images of single yeast cells during aging, show that the abundance of several NPC components and NPC assembly factors decreases. Additionally, the single-cell life histories reveal that cells that better maintain those components are longer lived. The presence of herniations at the nuclear envelope of aged cells suggests that misassembled NPCs are accumulated in aged cells. Aged cells show decreased dynamics of transcription factor shuttling and increased nuclear compartmentalization. These functional changes are likely caused by the presence of misassembled NPCs, as we find that two NPC assembly mutants show similar transport phenotypes as aged cells. We conclude that NPC interphase assembly is a major challenge for aging mitotic cells.
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Affiliation(s)
- Irina L Rempel
- European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Matthew M Crane
- Department of Pathology, University of Washington, Seattle, United States
| | - David J Thaller
- Department of Cell Biology, Yale School of Medicine, New Haven, United States
| | - Ankur Mishra
- Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Daniel Pm Jansen
- European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Georges Janssens
- European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Petra Popken
- European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Arman Akşit
- European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Matt Kaeberlein
- Department of Pathology, University of Washington, Seattle, United States
| | - Erik van der Giessen
- Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Anton Steen
- European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Patrick R Onck
- Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - C Patrick Lusk
- Department of Cell Biology, Yale School of Medicine, New Haven, United States
| | - Liesbeth M Veenhoff
- European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, Groningen, Netherlands
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8
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Yin Z, Chen C, Yang J, Feng W, Liu X, Zuo R, Wang J, Yang L, Zhong K, Gao C, Zhang H, Zheng X, Wang P, Zhang Z. Histone acetyltransferase MoHat1 acetylates autophagy-related proteins MoAtg3 and MoAtg9 to orchestrate functional appressorium formation and pathogenicity in Magnaporthe oryzae. Autophagy 2019; 15:1234-1257. [PMID: 30776962 DOI: 10.1080/15548627.2019.1580104] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Macroautophagy/autophagy is critical for normal appressorium formation and pathogenicity of the rice blast fungus Magnaporthe oryzae, but the molecular base of autophagy linked to pathogenicity remains elusive in this or other pathogenic fungi. We found that MoHat1, a histone acetyltransferase (HAT) homolog, had a role in the regulation of autophagy through the acetylation of autophagy related proteins MoAtg3 and MoAtg9. We also found that MoHat1 was subject to regulation by the protein kinase MoGsk1 that modulated the translocation of MoHat1 from the nucleus to the cytoplasm with the assistance of MoSsb1, a protein chaperone. The alternation of intracellular location affected MoHat1 in the modification of cytosolic autophagy proteins that maintained normal autophagy. Furthermore, we provided evidence linking acetylation of MoAtg3 and MoAtg9 by MoHat1 to functional appressorium development and pathogenicity. Together with the first report of MoAtg9 being subject to acetylation regulation by MoHat1, our studies depicted how MoHat1 regulated autophagy in conjunction with MoGsk1 and how normal autophagy was linked to appressorium formation and function and pathogenicity of M. oryzae. Abbreviations: A/Ala: alanine; AP: autophagosome; Atg genes/proteins: autophagy-related genes/proteins; BiFC: bimolecular fluorescence complementation; co-IP: co-immunoprecipitation; DAPI: 4', 6-diamidino-2-phenylindole; D/Asp: aspartic acid; GFP: green fluorescent protein; GSK3: glycogen synthase kinase 3; HAT: histone acetyltransferase; Hsp70: heat-shock protein 70; IH: invasive hyphae; K/Lys: lysine; MMS: methyl methanesulfonate; Mo: Magnaporthe oryzae; PAS: phagophore assembly site; PE: phosphatidylethanolamine; PtdIns3K: phosphatidylinositol 3-kinase; R/Arg: arginine; S/Ser: serine; T/Thr: threonine; TOR: target of rapamycin; WT: wild type; YFP: yellow fluorescent protein.
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Affiliation(s)
- Ziyi Yin
- a Department of Plant Pathology, College of Plant Protection , Nanjing Agricultural University , Nanjing , China.,b Key Laboratory of Integrated Management of Crop Diseases and Pests , Ministry of Education , Nanjing , China
| | - Chen Chen
- a Department of Plant Pathology, College of Plant Protection , Nanjing Agricultural University , Nanjing , China.,b Key Laboratory of Integrated Management of Crop Diseases and Pests , Ministry of Education , Nanjing , China
| | - Jie Yang
- a Department of Plant Pathology, College of Plant Protection , Nanjing Agricultural University , Nanjing , China.,b Key Laboratory of Integrated Management of Crop Diseases and Pests , Ministry of Education , Nanjing , China
| | - Wanzhen Feng
- a Department of Plant Pathology, College of Plant Protection , Nanjing Agricultural University , Nanjing , China.,b Key Laboratory of Integrated Management of Crop Diseases and Pests , Ministry of Education , Nanjing , China
| | - Xinyu Liu
- a Department of Plant Pathology, College of Plant Protection , Nanjing Agricultural University , Nanjing , China.,b Key Laboratory of Integrated Management of Crop Diseases and Pests , Ministry of Education , Nanjing , China
| | - Rongfang Zuo
- a Department of Plant Pathology, College of Plant Protection , Nanjing Agricultural University , Nanjing , China.,b Key Laboratory of Integrated Management of Crop Diseases and Pests , Ministry of Education , Nanjing , China
| | - Jingzhen Wang
- a Department of Plant Pathology, College of Plant Protection , Nanjing Agricultural University , Nanjing , China.,b Key Laboratory of Integrated Management of Crop Diseases and Pests , Ministry of Education , Nanjing , China
| | - Lina Yang
- a Department of Plant Pathology, College of Plant Protection , Nanjing Agricultural University , Nanjing , China.,b Key Laboratory of Integrated Management of Crop Diseases and Pests , Ministry of Education , Nanjing , China
| | - Kaili Zhong
- a Department of Plant Pathology, College of Plant Protection , Nanjing Agricultural University , Nanjing , China.,b Key Laboratory of Integrated Management of Crop Diseases and Pests , Ministry of Education , Nanjing , China
| | - Chuyun Gao
- a Department of Plant Pathology, College of Plant Protection , Nanjing Agricultural University , Nanjing , China.,b Key Laboratory of Integrated Management of Crop Diseases and Pests , Ministry of Education , Nanjing , China
| | - Haifeng Zhang
- a Department of Plant Pathology, College of Plant Protection , Nanjing Agricultural University , Nanjing , China.,b Key Laboratory of Integrated Management of Crop Diseases and Pests , Ministry of Education , Nanjing , China
| | - Xiaobo Zheng
- a Department of Plant Pathology, College of Plant Protection , Nanjing Agricultural University , Nanjing , China.,b Key Laboratory of Integrated Management of Crop Diseases and Pests , Ministry of Education , Nanjing , China
| | - Ping Wang
- c Departments of Pediatrics, and Microbiology, Immunology, and Parasitology , Louisiana State University Health Sciences Center , New Orleans , LA , USA
| | - Zhengguang Zhang
- a Department of Plant Pathology, College of Plant Protection , Nanjing Agricultural University , Nanjing , China.,b Key Laboratory of Integrated Management of Crop Diseases and Pests , Ministry of Education , Nanjing , China
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9
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Jung Y, Seong KM, Baek JH, Kim J. Ssb2 is a novel factor in regulating synthesis and degradation of Gcn4 in Saccharomyces cerevisiae. Mol Microbiol 2018; 110:728-740. [PMID: 30039896 DOI: 10.1111/mmi.14088] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 07/20/2018] [Accepted: 07/21/2018] [Indexed: 12/17/2022]
Abstract
Yeast cells respond to environmental stress by inducing the master regulator Gcn4 to control genes involved in biosynthesis of amino acids and purine pathways. Gcn4 is a member of the basic leucine Zipper family and binds directly as a homodimer to a conserved regulatory region of target genes. Ssb2 was discovered to rescue the mutant Gcn4 which has a point mutation that decreases DNA-binding affinity. Ssb2 is part of the Hsp70 protein family responsible for protein quality control and it is thought that Ssb2 assists the passage of nascent polypeptide chains from the ribosomes. To characterize the mechanism behind the rescue of the mutant gcn4 phenotype, transcriptional activity and protein levels of Gcn4 were analyzed. We found that Ssb2 improved the expression of Gcn4 target genes by increasing the DNA-binding affinity of gcn4 mutants to target gene promoters under conditions of amino acid starvation. Gcn4 levels increased at both translational and post-translational levels without regulating GCN4 steady-state mRNA levels. We also found that the nuclear export signal of Ssb2 is required for interaction with Gcn4 and rescue of the gcn4 mutant phenotype. These findings suggest that Ssb2 is a critical factor that modulates Gcn4 functions in the nucleus and cytosol.
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Affiliation(s)
- Youjin Jung
- Laboratory of Biochemistry, Division of Life Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Ki Moon Seong
- Laboratory of Biochemistry, Division of Life Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Je-Hyun Baek
- Laboratory of Biochemistry, Division of Life Sciences, Korea University, Seoul, 02841, Republic of Korea
| | - Joon Kim
- Laboratory of Biochemistry, Division of Life Sciences, Korea University, Seoul, 02841, Republic of Korea
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10
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Chatterjee K, Nostramo RT, Wan Y, Hopper AK. tRNA dynamics between the nucleus, cytoplasm and mitochondrial surface: Location, location, location. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2018; 1861:373-386. [PMID: 29191733 PMCID: PMC5882565 DOI: 10.1016/j.bbagrm.2017.11.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 11/19/2017] [Accepted: 11/23/2017] [Indexed: 01/20/2023]
Abstract
Although tRNAs participate in the essential function of protein translation in the cytoplasm, tRNA transcription and numerous processing steps occur in the nucleus. This subcellular separation between tRNA biogenesis and function requires that tRNAs be efficiently delivered to the cytoplasm in a step termed "primary tRNA nuclear export". Surprisingly, tRNA nuclear-cytoplasmic traffic is not unidirectional, but, rather, movement is bidirectional. Cytoplasmic tRNAs are imported back to the nucleus by the "tRNA retrograde nuclear import" step which is conserved from budding yeast to vertebrate cells and has been hijacked by viruses, such as HIV, for nuclear import of the viral reverse transcription complex in human cells. Under appropriate environmental conditions cytoplasmic tRNAs that have been imported into the nucleus return to the cytoplasm via the 3rd nuclear-cytoplasmic shuttling step termed "tRNA nuclear re-export", that again is conserved from budding yeast to vertebrate cells. We describe the 3 steps of tRNA nuclear-cytoplasmic movements and their regulation. There are multiple tRNA nuclear export and import pathways. The different tRNA nuclear exporters appear to possess substrate specificity leading to the tantalizing possibility that the cellular proteome may be regulated at the level of tRNA nuclear export. Moreover, in some organisms, such as budding yeast, the pre-tRNA splicing heterotetrameric endonuclease (SEN), which removes introns from pre-tRNAs, resides on the cytoplasmic surface of the mitochondria. Therefore, we also describe the localization of the SEN complex to mitochondria and splicing of pre-tRNA on mitochondria, which occurs prior to the participation of tRNAs in protein translation. This article is part of a Special Issue entitled: SI: Regulation of tRNA synthesis and modification in physiological conditions and disease edited by Dr. Boguta Magdalena.
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Affiliation(s)
- Kunal Chatterjee
- The Ohio State University Comprehensive Cancer Research Center, United States; Department of Molecular Genetics, The Ohio State University, United States; Center for RNA Biology, The Ohio State University, United States
| | - Regina T Nostramo
- Department of Molecular Genetics, The Ohio State University, United States; Center for RNA Biology, The Ohio State University, United States
| | - Yao Wan
- The Ohio State University Comprehensive Cancer Research Center, United States; Department of Molecular Genetics, The Ohio State University, United States; Center for RNA Biology, The Ohio State University, United States
| | - Anita K Hopper
- Department of Molecular Genetics, The Ohio State University, United States; Center for RNA Biology, The Ohio State University, United States.
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11
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Two chaperones locked in an embrace: structure and function of the ribosome-associated complex RAC. Nat Struct Mol Biol 2017; 24:611-619. [PMID: 28771464 DOI: 10.1038/nsmb.3435] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 06/14/2017] [Indexed: 12/26/2022]
Abstract
Chaperones, which assist protein folding are essential components of every living cell. The yeast ribosome-associated complex (RAC) is a chaperone that is highly conserved in eukaryotic cells. The RAC consists of the J protein Zuo1 and the unconventional Hsp70 homolog Ssz1. The RAC heterodimer stimulates the ATPase activity of the ribosome-bound Hsp70 homolog Ssb, which interacts with nascent polypeptide chains to facilitate de novo protein folding. In addition, the RAC-Ssb system is required to maintain the fidelity of protein translation. Recent work reveals important details of the unique structures of RAC and Ssb and identifies how the chaperones interact with the ribosome. The new findings start to uncover how the exceptional chaperone triad cooperates in protein folding and maintenance of translational fidelity and its connection to extraribosomal functions.
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12
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Sahu U, Rajendra VKH, Kapnoor SS, Bhagavat R, Chandra N, Rangarajan PN. Methionine synthase is localized to the nucleus in Pichia pastoris and Candida albicans and to the cytoplasm in Saccharomyces cerevisiae. J Biol Chem 2017; 292:14730-14746. [PMID: 28701466 DOI: 10.1074/jbc.m117.783019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 07/10/2017] [Indexed: 11/06/2022] Open
Abstract
Methionine synthase (MS) catalyzes methylation of homocysteine, the last step in the biosynthesis of methionine, which is essential for the regeneration of tetrahydrofolate and biosynthesis of S-adenosylmethionine. Here, we report that MS is localized to the nucleus of Pichia pastoris and Candida albicans but is cytoplasmic in Saccharomyces cerevisiae The P. pastoris strain carrying a deletion of the MET6 gene encoding MS (Ppmet6) exhibits methionine as well as adenine auxotrophy indicating that MS is required for methionine as well as adenine biosynthesis. Nuclear localization of P. pastoris MS (PpMS) was abrogated by the deletion of 107 C-terminal amino acids or the R742A mutation. In silico analysis of the PpMS structure indicated that PpMS may exist in a dimer-like configuration in which Arg-742 of a monomer forms a salt bridge with Asp-113 of another monomer. Biochemical studies indicate that R742A as well as D113R mutations abrogate nuclear localization of PpMS and its ability to reverse methionine auxotrophy of Ppmet6 Thus, association of two PpMS monomers through the interaction of Arg-742 and Asp-113 is essential for catalytic activity and nuclear localization. When PpMS is targeted to the cytoplasm employing a heterologous nuclear export signal, it is expressed at very low levels and is unable to reverse methionine and adenine auxotrophy of Ppmet6 Thus, nuclear localization is essential for the stability and function of MS in P. pastoris. We conclude that nuclear localization of MS is a unique feature of respiratory yeasts such as P. pastoris and C. albicans, and it may have novel moonlighting functions in the nucleus.
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Affiliation(s)
- Umakant Sahu
- From the Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Vinod K H Rajendra
- From the Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Shankar S Kapnoor
- From the Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Raghu Bhagavat
- From the Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Nagasuma Chandra
- From the Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Pundi N Rangarajan
- From the Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
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13
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Gumiero A, Conz C, Gesé GV, Zhang Y, Weyer FA, Lapouge K, Kappes J, von Plehwe U, Schermann G, Fitzke E, Wölfle T, Fischer T, Rospert S, Sinning I. Interaction of the cotranslational Hsp70 Ssb with ribosomal proteins and rRNA depends on its lid domain. Nat Commun 2016; 7:13563. [PMID: 27882919 PMCID: PMC5123055 DOI: 10.1038/ncomms13563] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 10/13/2016] [Indexed: 12/22/2022] Open
Abstract
Cotranslational chaperones assist in de novo folding of nascent polypeptides in all organisms. In yeast, the heterodimeric ribosome-associated complex (RAC) forms a unique chaperone triad with the Hsp70 homologue Ssb. We report the X-ray structure of full length Ssb in the ATP-bound open conformation at 2.6 Å resolution and identify a positively charged region in the α-helical lid domain (SBDα), which is present in all members of the Ssb-subfamily of Hsp70s. Mutational analysis demonstrates that this region is strictly required for ribosome binding. Crosslinking shows that Ssb binds close to the tunnel exit via contacts with both, ribosomal proteins and rRNA, and that specific contacts can be correlated with switching between the open (ATP-bound) and closed (ADP-bound) conformation. Taken together, our data reveal how Ssb dynamics on the ribosome allows for the efficient interaction with nascent chains upon RAC-mediated activation of ATP hydrolysis. In yeast, the heterodimeric ribosome-associated complex (RAC) acts in concert with the Hsp70 protein Ssb, forming a unique chaperone triad. Here the authors use structural and biochemical approaches to shed light on how translation and folding are coupled in eukaryotes.
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Affiliation(s)
- Andrea Gumiero
- Heidelberg University Biochemistry Center (BZH), INF 328, D-69120 Heidelberg, Germany
| | - Charlotte Conz
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, D-79104 Freiburg, Germany.,BIOSS Centre for Biological Signaling Studies, University of Freiburg, D-79104 Freiburg, Germany
| | - Genís Valentín Gesé
- Heidelberg University Biochemistry Center (BZH), INF 328, D-69120 Heidelberg, Germany
| | - Ying Zhang
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, D-79104 Freiburg, Germany.,BIOSS Centre for Biological Signaling Studies, University of Freiburg, D-79104 Freiburg, Germany
| | - Felix Alexander Weyer
- Heidelberg University Biochemistry Center (BZH), INF 328, D-69120 Heidelberg, Germany
| | - Karine Lapouge
- Heidelberg University Biochemistry Center (BZH), INF 328, D-69120 Heidelberg, Germany
| | - Julia Kappes
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, D-79104 Freiburg, Germany
| | - Ulrike von Plehwe
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, D-79104 Freiburg, Germany
| | - Géza Schermann
- Heidelberg University Biochemistry Center (BZH), INF 328, D-69120 Heidelberg, Germany
| | - Edith Fitzke
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, D-79104 Freiburg, Germany.,BIOSS Centre for Biological Signaling Studies, University of Freiburg, D-79104 Freiburg, Germany
| | - Tina Wölfle
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, D-79104 Freiburg, Germany.,BIOSS Centre for Biological Signaling Studies, University of Freiburg, D-79104 Freiburg, Germany
| | - Tamás Fischer
- Heidelberg University Biochemistry Center (BZH), INF 328, D-69120 Heidelberg, Germany
| | - Sabine Rospert
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, D-79104 Freiburg, Germany.,BIOSS Centre for Biological Signaling Studies, University of Freiburg, D-79104 Freiburg, Germany
| | - Irmgard Sinning
- Heidelberg University Biochemistry Center (BZH), INF 328, D-69120 Heidelberg, Germany
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14
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N-Myristoylation of the Rpt2 subunit of the yeast 26S proteasome is implicated in the subcellular compartment-specific protein quality control system. J Proteomics 2015; 130:33-41. [PMID: 26344132 DOI: 10.1016/j.jprot.2015.08.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 08/14/2015] [Accepted: 08/27/2015] [Indexed: 12/14/2022]
Abstract
Ubiquitination is the posttranslational modification of a protein by covalent attachment of ubiquitin. Controlled proteolysis via the ubiquitin-proteasome system (\UPS) alleviates cellular stress by clearing misfolded proteins. In budding yeast, UPS within the nucleus degrades the nuclear proteins as well as proteins imported from the cytoplasm. While the predominantly nuclear localization of the yeast proteasome is maintained by the importin-mediated transport, N-myristoylation of the proteasome subunit Rpt2 was indicated to cause dynamic nucleo-cytoplasmic localization of proteasomes. Here, we quantitatively analyzed the ubiquitinated peptides using anti-K-ε-GG antibody in yeast cell lines with or without a mutation in the N-myristoylation site of Rpt2 and detected upregulated ubiquitination of proteins with nucleo-cytoplasmic localizations in the mutant strains. Moreover, both the protein and ubiquitinated peptide levels of two Hsp70 family chaperones involved in the nuclear import of misfolded proteins, Ssa and Sse1, were elevated in the mutant strains, whereas levels of an Hsp70 family chaperone involved in the nuclear export, Ssb, were reduced. Taken together, our results indicate that N-myristoylation of Rpt2 is involved in controlled proteolysis via regulation of the nucleo-cytoplasmic localization of the yeast proteasome.
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15
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Xu D, Marquis K, Pei J, Fu SC, Cağatay T, Grishin NV, Chook YM. LocNES: a computational tool for locating classical NESs in CRM1 cargo proteins. Bioinformatics 2015; 31:1357-65. [PMID: 25515756 PMCID: PMC4410651 DOI: 10.1093/bioinformatics/btu826] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 12/08/2014] [Accepted: 12/09/2014] [Indexed: 01/01/2023] Open
Abstract
MOTIVATION Classical nuclear export signals (NESs) are short cognate peptides that direct proteins out of the nucleus via the CRM1-mediated export pathway. CRM1 regulates the localization of hundreds of macromolecules involved in various cellular functions and diseases. Due to the diverse and complex nature of NESs, reliable prediction of the signal remains a challenge despite several attempts made in the last decade. RESULTS We present a new NES predictor, LocNES. LocNES scans query proteins for NES consensus-fitting peptides and assigns these peptides probability scores using Support Vector Machine model, whose feature set includes amino acid sequence, disorder propensity, and the rank of position-specific scoring matrix score. LocNES demonstrates both higher sensitivity and precision over existing NES prediction tools upon comparative analysis using experimentally identified NESs. AVAILABILITY AND IMPLEMENTATION LocNES is freely available at http://prodata.swmed.edu/LocNES CONTACT: yuhmin.chook@utsouthwestern.edu SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Darui Xu
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9041, USA, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA, Department of Biophysics and Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA
| | - Kara Marquis
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9041, USA, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA, Department of Biophysics and Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA
| | - Jimin Pei
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9041, USA, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA, Department of Biophysics and Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA
| | - Szu-Chin Fu
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9041, USA, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA, Department of Biophysics and Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA
| | - Tolga Cağatay
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9041, USA, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA, Department of Biophysics and Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA
| | - Nick V Grishin
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9041, USA, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA, Department of Biophysics and Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9041, USA, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA, Department of Biophysics and Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9041, USA, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA, Department of Biophysics and Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA
| | - Yuh Min Chook
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9041, USA, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA, Department of Biophysics and Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9041, USA, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA, Department of Biophysics and Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9050, USA
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16
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Fischer U, Schäuble N, Schütz S, Altvater M, Chang Y, Boulos Faza M, Panse VG. A non-canonical mechanism for Crm1-export cargo complex assembly. eLife 2015; 4:e05745. [PMID: 25895666 PMCID: PMC4402694 DOI: 10.7554/elife.05745] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 03/26/2015] [Indexed: 01/19/2023] Open
Abstract
The transport receptor Crm1 mediates the export of diverse cargos containing leucine-rich nuclear export signals (NESs) through complex formation with RanGTP. To ensure efficient cargo release in the cytoplasm, NESs have evolved to display low affinity for Crm1. However, mechanisms that overcome low affinity to assemble Crm1-export complexes in the nucleus remain poorly understood. In this study, we reveal a new type of RanGTP-binding protein, Slx9, which facilitates Crm1 recruitment to the 40S pre-ribosome-associated NES-containing adaptor Rio2. In vitro, Slx9 binds Rio2 and RanGTP, forming a complex. This complex directly loads Crm1, unveiling a non-canonical stepwise mechanism to assemble a Crm1-export complex. A mutation in Slx9 that impairs Crm1-export complex assembly inhibits 40S pre-ribosome export. Thus, Slx9 functions as a scaffold to optimally present RanGTP and the NES to Crm1, therefore, triggering 40S pre-ribosome export. This mechanism could represent one solution to the paradox of weak binding events underlying rapid Crm1-mediated export.
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Affiliation(s)
- Ute Fischer
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Nico Schäuble
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Sabina Schütz
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland
- Molecular Life Science, Graduate School, Zurich, Switzerland
| | - Martin Altvater
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland
- Molecular Life Science, Graduate School, Zurich, Switzerland
| | - Yiming Chang
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Marius Boulos Faza
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Vikram Govind Panse
- Institute of Biochemistry, Department of Biology, ETH Zurich, Zurich, Switzerland
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17
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Takano A, Kajita T, Mochizuki M, Endo T, Yoshihisa T. Cytosolic Hsp70 and co-chaperones constitute a novel system for tRNA import into the nucleus. eLife 2015; 4:e04659. [PMID: 25853343 PMCID: PMC4432389 DOI: 10.7554/elife.04659] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2014] [Accepted: 04/05/2015] [Indexed: 01/31/2023] Open
Abstract
tRNAs are unique among various RNAs in that they shuttle between the nucleus and the cytoplasm, and their localization is regulated by nutrient conditions. Although nuclear export of tRNAs has been well documented, the import machinery is poorly understood. Here, we identified Ssa2p, a major cytoplasmic Hsp70 in Saccharomyces cerevisiae, as a tRNA-binding protein whose deletion compromises nuclear accumulation of tRNAs upon nutrient starvation. Ssa2p recognizes several structural features of tRNAs through its nucleotide-binding domain, but prefers loosely-folded tRNAs, suggesting that Ssa2p has a chaperone-like activity for RNAs. Ssa2p also binds Nup116, one of the yeast nucleoporins. Sis1p and Ydj1p, cytoplasmic co-chaperones for Ssa proteins, were also found to contribute to the tRNA import. These results unveil a novel function of the Ssa2p system as a tRNA carrier for nuclear import by a novel mode of substrate recognition. Such Ssa2p-mediated tRNA import likely contributes to quality control of cytosolic tRNAs.
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Affiliation(s)
- Akira Takano
- Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Takuya Kajita
- Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Makoto Mochizuki
- Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Toshiya Endo
- Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, Japan
- Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, Japan
| | - Tohru Yoshihisa
- Graduate School of Life Science, University of Hyogo, Kobe, Japan
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18
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Chen DH, Huang Y, Liu C, Ruan Y, Shen WH. Functional conservation and divergence of J-domain-containing ZUO1/ZRF orthologs throughout evolution. PLANTA 2014; 239:1159-1173. [PMID: 24659052 DOI: 10.1007/s00425-014-2058-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 03/05/2014] [Indexed: 06/03/2023]
Abstract
Heat shock protein 40s (Hsp40s), also known as J-proteins, are conserved in prokaryotes and eukaryotes. The Zuotin/Zuotin-related factor (ZUO1/ZRF) family belongs to a novel Hsp40 clade exclusively found in eukaryotes. Zuotin/Zuotin-related factor proteins are characterized by a large N terminal ZUO1 domain originally identified in the yeast ZUO1 protein. The ZUO1 domain is characterized by a highly conserved J-domain, together with an atypical UBD domain first identified in the human ZRF1 protein. Furthermore, ZUO1/ZRF protein families in animals and plants harbor a pair of C terminal SANT domains, suggesting the divergence of their functions with those in fungi. Zuotin/Zuotin-related factor proteins retain the ancestral function as an Hsp70co-chaperone implicated in protein folding and renaturation after stress; these proteins also perform diverse neofunctions in the cytoplasm and transcriptional and/or epigenetic regulatory functions in the nucleus. Therefore, these proteins are involved in translational fidelity control, ribosomal biogenesis, asymmetric cell division, cell cycle, apoptosis, differentiation, and tumorigenesis. The results of sequence and domain organization analysis of proteins from diverse organisms provided valuable insights into the evolutionary conservation and diversity of ZUO1/ZRF protein family. Further, phylogenetic analysis provides a platform for future functional investigation on the ZUO1/ZRF protein family, particularly in higher plants.
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19
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Inhibition of Heat Tolerance and Nuclear Import of Gts1p by Ssa1p and Ssa2p. Biosci Biotechnol Biochem 2014; 75:323-30. [DOI: 10.1271/bbb.100743] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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20
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Hsp90 orchestrates transcriptional regulation by Hsf1 and cell wall remodelling by MAPK signalling during thermal adaptation in a pathogenic yeast. PLoS Pathog 2012; 8:e1003069. [PMID: 23300438 PMCID: PMC3531498 DOI: 10.1371/journal.ppat.1003069] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2012] [Accepted: 10/18/2012] [Indexed: 01/30/2023] Open
Abstract
Thermal adaptation is essential in all organisms. In yeasts, the heat shock response is commanded by the heat shock transcription factor Hsf1. Here we have integrated unbiased genetic screens with directed molecular dissection to demonstrate that multiple signalling cascades contribute to thermal adaptation in the pathogenic yeast Candida albicans. We show that the molecular chaperone heat shock protein 90 (Hsp90) interacts with and down-regulates Hsf1 thereby modulating short term thermal adaptation. In the longer term, thermal adaptation depends on key MAP kinase signalling pathways that are associated with cell wall remodelling: the Hog1, Mkc1 and Cek1 pathways. We demonstrate that these pathways are differentially activated and display cross talk during heat shock. As a result ambient temperature significantly affects the resistance of C. albicans cells to cell wall stresses (Calcofluor White and Congo Red), but not osmotic stress (NaCl). We also show that the inactivation of MAP kinase signalling disrupts this cross talk between thermal and cell wall adaptation. Critically, Hsp90 coordinates this cross talk. Genetic and pharmacological inhibition of Hsp90 disrupts the Hsf1-Hsp90 regulatory circuit thereby disturbing HSP gene regulation and reducing the resistance of C. albicans to proteotoxic stresses. Hsp90 depletion also affects cell wall biogenesis by impairing the activation of its client proteins Mkc1 and Hog1, as well as Cek1, which we implicate as a new Hsp90 client in this study. Therefore Hsp90 modulates the short term Hsf1-mediated activation of the classic heat shock response, coordinating this response with long term thermal adaptation via Mkc1- Hog1- and Cek1-mediated cell wall remodelling. Candida albicans is one of the most persistent yeast pathogens known to man, causing frequent mucosal infections (thrush) in otherwise healthy individuals, and potentially fatal bloodstream infections in immunocompromised patients. C. albicans colonises warm-blooded animals and occupies thermally buffered niches. Yet during its evolution this pathogen has retained the classic heat shock response whilst other stress responses have diverged significantly. We have established that the essential, evolutionarily conserved molecular chaperone, Hsp90, coordinates thermal adaptation. Hsp90 interacts with and modulates the activity of the heat shock transcription factor, Hsf1, thereby controlling the expression of heat shock proteins required for the clearance of proteins damaged by proteotoxic stresses. In addition, Hsp90 modulates the activities of key MAP kinase signalling pathways that mediate cell wall remodelling and long term adaptation to heat shock. Loss of any of these factors results in a significant reduction in thermotolerance.
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21
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Vasicova P, Stradalova V, Halada P, Hasek J, Malcova I. Nuclear import of chromatin remodeler Isw1 is mediated by atypical bipartite cNLS and classical import pathway. Traffic 2012; 14:176-93. [PMID: 23121014 DOI: 10.1111/tra.12025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2012] [Revised: 10/29/2012] [Accepted: 11/01/2012] [Indexed: 11/28/2022]
Abstract
The protein Isw1 of Saccharomyces cerevisiae is an imitation-switch chromatin-remodeling factor. We studied the mechanisms of its nuclear import and found that the nuclear localization signal (NLS) mediating the transport of Isw1 into the nucleus is located at the end of the C-terminus of the protein (aa1079-1105). We show that it is an atypical bipartite signal with an unconventional linker of 19 aa (KRIR X(19) KKAK) and the only nuclear targeting signal within the Isw1 molecule. The efficiency of Isw1 nuclear import was found to be modulated by changes to the amino acid composition in the vicinity of the KRIR motif, but not by the linker length. Live-cell imaging of various karyopherin mutants and in vitro binding assays of Isw1NLS to importin-α revealed that the nuclear translocation of Isw1 is mediated by the classical import pathway. Analogous motifs to Isw1NLS are highly conserved in Isw1 homologues of other yeast species, and putative bipartite cNLS were identified in silico at the end of the C-termini of imitation switch (ISWI) proteins from higher eukaryotes. We suggest that the C-termini of the ISWI family proteins play an important role in their nuclear import.
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Affiliation(s)
- Pavla Vasicova
- Laboratory of Cell Reproduction, Institute of Microbiology v.v.i., Academy of Sciences of the Czech Republic, Videnska 1083, Cz-14220, Prague 4, Czech Republic
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Preissler S, Deuerling E. Ribosome-associated chaperones as key players in proteostasis. Trends Biochem Sci 2012; 37:274-83. [PMID: 22503700 DOI: 10.1016/j.tibs.2012.03.002] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 02/17/2012] [Accepted: 03/06/2012] [Indexed: 01/14/2023]
Abstract
De novo protein folding is delicate and error-prone and requires the guidance of molecular chaperones. Besides cytosolic and organelle-specific chaperones, cells have evolved ribosome-associated chaperones that support early folding events and prevent misfolding and aggregation. This class of chaperones includes the bacterial trigger factor (TF), the archaeal and eukaryotic nascent polypeptide-associated complex (NAC) and specialized eukaryotic heat shock protein (Hsp) 70/40 chaperones. This review focuses on the cellular activities of ribosome-associated chaperones and highlights new findings indicating additional functions beyond de novo folding. These activities include the assembly of oligomeric complexes, such as ribosomes, modulation of translation and targeting of proteins.
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Affiliation(s)
- Steffen Preissler
- Molecular Microbiology, Department of Biology, University of Konstanz, 78457 Konstanz, Germany
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Albanèse V, Reissmann S, Frydman J. A ribosome-anchored chaperone network that facilitates eukaryotic ribosome biogenesis. ACTA ACUST UNITED AC 2010; 189:69-81. [PMID: 20368619 PMCID: PMC2854368 DOI: 10.1083/jcb.201001054] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Ribosome-anchored proteins Jjj1 and Zuo1 function together with Hsp70 to mediate ribosome biogenesis (see also the companion paper from Koplin et al. in this issue). Molecular chaperones assist cellular protein folding as well as oligomeric complex assembly. In eukaryotic cells, several chaperones termed chaperones linked to protein synthesis (CLIPS) are transcriptionally and physically linked to ribosomes and are implicated in protein biosynthesis. In this study, we show that a CLIPS network comprising two ribosome-anchored J-proteins, Jjj1 and Zuo1, function together with their partner Hsp70 proteins to mediate the biogenesis of ribosomes themselves. Jjj1 and Zuo1 have overlapping but distinct functions in this complex process involving the coordinated assembly and remodeling of dozens of proteins on the ribosomal RNA (rRNA). Both Jjj1 and Zuo1 associate with nuclear 60S ribosomal biogenesis intermediates and play an important role in nuclear rRNA processing, leading to mature 25S rRNA. In addition, Zuo1, acting together with its Hsp70 partner, SSB (stress 70 B), also participates in maturation of the 35S rRNA. Our results demonstrate that, in addition to their known cytoplasmic roles in de novo protein folding, some ribosome-anchored CLIPS chaperones play a critical role in nuclear steps of ribosome biogenesis.
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Peisker K, Chiabudini M, Rospert S. The ribosome-bound Hsp70 homolog Ssb of Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1803:662-72. [PMID: 20226819 DOI: 10.1016/j.bbamcr.2010.03.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 03/01/2010] [Accepted: 03/04/2010] [Indexed: 11/29/2022]
Abstract
The Hsp70 homolog Ssb directly binds to the ribosome and contacts a variety of newly synthesized polypeptide chains as soon as they emerge from the ribosomal exit tunnel. For this reason a general role of Ssb in the de novo folding of newly synthesized proteins is highly suggestive. However, for more than a decade client proteins which require Ssb for proper folding have remained elusive. It was therefore speculated that Ssb, despite its ability to interact with a large variety of nascent polypeptides, may assist the folding of only a small and specific subset. Alternatively, it has been suggested that Ssb's function may be limited to the protection of nascent polypeptides from aggregation until downstream chaperones take over and actively fold their substrates. There is also evidence that Ssb, in parallel to a classical chaperone function, is involved in the regulation of cellular signaling processes. Here we aim to summarize what is currently known about Ssb's multiple functions and what remains to be ascertained by future research.
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Affiliation(s)
- Kristin Peisker
- Department of Cell and Molecular Biology, Biomedicinskt Centrum BMC, Uppsala, Sweden
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25
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Tapia H, Morano KA. Hsp90 nuclear accumulation in quiescence is linked to chaperone function and spore development in yeast. Mol Biol Cell 2009; 21:63-72. [PMID: 19889838 PMCID: PMC2801720 DOI: 10.1091/mbc.e09-05-0376] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The protein chaperone Hsp90 and its co-chaperone Sba1/p23 are found to accumulate in the nucleus of haploid yeast cells as glucose is exhausted and in sporulating diploids. Novel and existing Hsp90 mutants exhibit defects in nuclear translocation and spore development, linking these two phenomena. The 90-kDa heat-shock protein (Hsp90) operates in the context of a multichaperone complex to promote maturation of nuclear and cytoplasmic clients. We have discovered that Hsp90 and the cochaperone Sba1/p23 accumulate in the nucleus of quiescent Saccharomyces cerevisiae cells. Hsp90 nuclear accumulation was unaffected in sba1Δ cells, demonstrating that Hsp82 translocates independently of Sba1. Translocation of both chaperones was dependent on the α/β importin SRP1/KAP95. Hsp90 nuclear retention was coincident with glucose exhaustion and seems to be a starvation-specific response, as heat shock or 10% ethanol stress failed to elicit translocation. We generated nuclear accumulation-defective HSP82 mutants to probe the nature of this targeting event and identified a mutant with a single amino acid substitution (I578F) sufficient to retain Hsp90 in the cytoplasm in quiescent cells. Diploid hsp82-I578F cells exhibited pronounced defects in spore wall construction and maturation, resulting in catastrophic sporulation. The mislocalization and sporulation phenotypes were shared by another previously identified HSP82 mutant allele. Pharmacological inhibition of Hsp90 with macbecin in sporulating diploid cells also blocked spore formation, underscoring the importance of this chaperone in this developmental program.
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Affiliation(s)
- Hugo Tapia
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, TX 77030, USA
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Neuber A, Franke J, Wittstruck A, Schlenstedt G, Sommer T, Stade K. Nuclear export receptor Xpo1/Crm1 is physically and functionally linked to the spindle pole body in budding yeast. Mol Cell Biol 2008; 28:5348-58. [PMID: 18573877 PMCID: PMC2519715 DOI: 10.1128/mcb.02043-07] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 12/28/2007] [Accepted: 06/16/2008] [Indexed: 01/13/2023] Open
Abstract
The spindle pole body (SPB) represents the microtubule organizing center in the budding yeast Saccharomyces cerevisiae. It is a highly structured organelle embedded in the nuclear membrane, which is required to anchor microtubules on both sides of the nuclear envelope. The protein Spc72, a component of the SPB, is located at the cytoplasmic face of this organelle and serves as a receptor for the gamma-tubulin complex. In this paper we show that it is also a binding partner of the nuclear export receptor Xpo1/Crm1. Xpo1 binds its cargoes in a Ran-dependent fashion via a short leucine-rich nuclear export signal (NES). We show that binding of Spc72 to Xpo1 depends on Ran-GTP and a functional NES in Spc72. Mutations in this NES have severe consequences for mitotic spindle morphology in vivo. This is also the case for xpo1 mutants, which show a reduction in cytoplasmic microtubules. In addition, we find a subpopulation of Xpo1 localized at the SPB. Based on these data, we propose a functional link between Xpo1 and the SPB and discuss a role for this exportin in spindle biogenesis in budding yeast.
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Affiliation(s)
- Anja Neuber
- Max Delbrück Centrum für Molekulare Medizin, Robert Rössle Str. 10, 13092 Berlin, Germany
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27
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Tkach JM, Glover JR. Nucleocytoplasmic trafficking of the molecular chaperone Hsp104 in unstressed and heat-shocked cells. Traffic 2007; 9:39-56. [PMID: 17973656 DOI: 10.1111/j.1600-0854.2007.00666.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Hsp104 is a molecular chaperone in yeast that restores solubility and activity to inactivated proteins after severe heat shock. We investigated the mechanisms that influence Hsp104 subcellular distribution in both unstressed and heat-shocked cells. In unstressed cells, Hsp104 and a green fluorescent protein-Hsp104 fusion protein were detected in both the nucleus and the cytoplasm. We demonstrate that a 17-amino-acid sequence of Hsp104 nuclear localization sequence 17 (NLS17) is sufficient to target a reporter molecule to the nucleus and is also necessary for normal Hsp104 subcellular distribution. The nuclear targeting function of NLS17 is genetically dependent on KAP95 and KAP121. In addition, wild-type Hsp104, but not an NLS17-mutated Hsp104 variant, accumulated in the nucleus of cells depleted for the general export factor Xpo1. Interestingly, severe, nonlethal heat shock enhances the nuclear levels of Hsp104 in an NLS17-independent manner. Under these conditions, we demonstrate that karyopherin-mediated nuclear transport is impaired, while the integrity of the nuclear-cytoplasmic barrier remains intact. Based on these observations, we propose that Hsp104 continues to access the nucleus during severe heat shock using a karyopherin-independent mechanism.
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Affiliation(s)
- Johnny M Tkach
- Department of Biochemistry, University of Toronto, Room 5302, Medical Sciences Building, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
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28
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Saito Y, Yamagishi N, Hatayama T. Different localization of Hsp105 family proteins in mammalian cells. Exp Cell Res 2007; 313:3707-17. [PMID: 17643418 DOI: 10.1016/j.yexcr.2007.06.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Revised: 05/18/2007] [Accepted: 06/10/2007] [Indexed: 11/18/2022]
Abstract
Hsp105alpha and Hsp105beta of the HSP105 family are alternatively spliced products derived from an hsp 105 gene transcript. Hsp105alpha is constitutively expressed and also induced by various stress, whereas Hsp105beta, lacking 44 amino acids from Hsp105alpha, is specifically expressed during mild heat shock. Although Hsp105alpha is shown to localize in the cytoplasm of mammalian cells, cellular localization of Hsp105beta is not known. In this study, we showed that Hsp105beta localized in the nucleus of cells in contrast to cytoplasmic Hsp105alpha, suggesting that these proteins function in different cellular compartments of cells. Using deletion and substitution mutants of Hsp105alpha and Hsp105beta, we revealed that these proteins had a functional nuclear localization signal (NLS) and a nuclear export signal (NES). Furthermore, Hsp105alpha accumulated in the nucleus of cells when treated with leptomycin B, a specific inhibitor of NES-dependent nuclear export. siRNA for importin beta, an essential component for NLS-dependent nuclear transport, inhibited the nuclear localization of Hsp105beta. Furthermore, the 44 amino acids sequence found in Hsp105alpha but not in Hsp105beta suppressed the NLS activity. Thus, the different localization of Hsp105alpha and Hsp105beta is suggested to be due to the suppressed NLS activity in Hsp105alpha.
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Affiliation(s)
- Youhei Saito
- Department of Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan
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29
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Matsumoto R, Nam HW, Agrawal GK, Kim YS, Iwahashi H, Rakwal R. Exploring Novel Function of Yeast Ssa1/2p by Quantitative Profiling Proteomics Using NanoESI-LC−MS/MS. J Proteome Res 2007; 6:3465-74. [PMID: 17691831 DOI: 10.1021/pr070042n] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the present study, we profiled proteins in ssa1/2 mutant and wild-type using one-dimensional gel electrophoresis coupled with liquid chromatography and mass spectrometry to reveal a total of 322 proteins. Sixty and 84 nonredundant proteins were detected in ssa1/2 and wild-type, respectively, whereas 178 were common. A quantitative profiling proteomic approach using a modified N-terminal isotope tagging method was undertaken to determine quantitative changes in proteins between mutant and wild-type. Out of 210 identified proteins selected for quantification, 103 propionylated proteins were obtained. Eight only D0-propionylated protein (wild-type) and 4 only D5-propionylated proteins (ssa1/2) were detected; 90 proteins were overlapped in the ssa1/2 mutant and wild-type. In the ssa1/2 mutant, 28 proteins were up-regulated and 26 were down-regulated. The expression levels of the rest of 49 proteins were not changed compared with the wild-type. Furthermore, non-correlation between mRNA and protein expressions was found. Among up-regulated proteins, 19 proteins involved in protein synthesis, chromatin condensation, and silencing showed unchanged mRNA expression levels. Among down-regulated proteins, 21 proteins consisting mainly of transcription factors showed unchanged mRNA expressions. Surprisingly, several proteins involved in protein synthesis were also found among the down-regulated proteins. These results suggested that the proteins showing changed protein expressions and unchanged mRNA expressions were affected by the deletion of SSA1 and SSA2 genes at translational efficiency, mRNA degradation, or protein degradation. Moreover, we found the proteins related to chromosomal control were up-regulated in ssa1/2 mutant, a novel finding of this study, suggesting that the Ssa1/2p might contribute to chromosomal control.
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Affiliation(s)
- Rena Matsumoto
- International Patent Organism Depositary (IPOD), National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1-1 Higashi, Tsukuba 305-8566, Japan
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30
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Stoler S, Rogers K, Weitze S, Morey L, Fitzgerald-Hayes M, Baker RE. Scm3, an essential Saccharomyces cerevisiae centromere protein required for G2/M progression and Cse4 localization. Proc Natl Acad Sci U S A 2007; 104:10571-6. [PMID: 17548816 PMCID: PMC1885823 DOI: 10.1073/pnas.0703178104] [Citation(s) in RCA: 158] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A universal mark of centromeric chromatin is its packaging by a variant of histone H3 known as centromeric H3 (CenH3). The mechanism by which CenH3s are incorporated specifically into centromere DNA or the specialized function they serve there is not known. In a genetic approach to identify factors involved in CenH3 deposition, we screened for dosage suppressors of a temperature-sensitive cse4 allele in Saccharomyces cerevisiae (Cse4 is the S. cerevisiae CenH3). Independent screens yielded ORF YDL139C, which we named SCM3. Dosage suppression by SCM3 was specific for alleles affecting the histone fold domain of Cse4. Copurification and two-hybrid studies showed that Scm3 and Cse4 interact in vivo, and chromatin immunoprecipitation revealed that Scm3, like Cse4, is found associated with centromere DNA. Scm3 contains two essential protein domains, a Leu-rich nuclear export signal and a heptad repeat domain that is widely conserved in fungi. A conditional scm3 allele was generated to allow us to deplete Scm3. Upon Scm3 depletion, cells undergo a Mad2-dependent G2/M arrest, and centromere localization of Cse4 is perturbed. We suggest that S. cerevisiae Scm3 defines a previously undescribed family of fungal kinetochore proteins important for CenH3 localization.
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Affiliation(s)
- Sam Stoler
- *Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003; and
| | - Kelly Rogers
- Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655
| | - Scott Weitze
- *Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003; and
| | - Lisa Morey
- *Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003; and
| | - Molly Fitzgerald-Hayes
- *Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003; and
| | - Richard E. Baker
- Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655
- To whom correspondence should be addressed. E-mail:
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Zhang S, Hacham M, Panepinto J, Hu G, Shin S, Zhu X, Williamson PR. The Hsp70 member, Ssa1, acts as a DNA-binding transcriptional co-activator of laccase in Cryptococcus neoformans. Mol Microbiol 2006; 62:1090-101. [PMID: 17040492 DOI: 10.1111/j.1365-2958.2006.05422.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Hsp70 proteins are a well-known class of chaperones that have also been described to have roles in cellular regulation. Here, we show that a Cryptococcus neoformans Hsp70 homologue Ssa1 acts as a DNA-binding transcriptional co-activator of the fungal virulence factor, laccase, via binding to a GC-rich element within the 5'-UAS in response to glucose starvation, iron, copper, calcium and temperature. In addition, Ssa1 forms a regulatory complex with heat shock transcription factor and TATA-binding protein during laccase induction. Furthermore, deletion of Ssa1 results in reduced laccase and attenuated virulence using a mouse model. These results indicate that Hsp70 functions as a stress-related transcriptional co-activator required for fungal virulence.
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Affiliation(s)
- Shirong Zhang
- Section of Infectious Diseases, Department of Medicine, University of Illinois at Chicago College of Medicine, Chicago, IL, USA.
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32
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Quan X, Tsoulos P, Kuritzky A, Zhang R, Stochaj U. The carrier Msn5p/Kap142p promotes nuclear export of the hsp70 Ssa4p and relocates in response to stress. Mol Microbiol 2006; 62:592-609. [PMID: 17020589 DOI: 10.1111/j.1365-2958.2006.05395.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytoplasmic hsp70s like yeast Ssa4p shuttle between nucleus and cytoplasm under normal growth conditions but accumulate in nuclei upon stress. This nuclear accumulation is only transient, and Ssa4p relocates to the cytoplasm when cells recover. We show here that Ssa4p nuclear export is independent of Xpol/Crm1 and identify the importin-beta family member Msn5p/Kap142p as the exporter for Ssa4p. In growing cells and in vitro, Msn5p and Ssa4p generate genuine export complexes that require Ran/Gsp1p-GTP. Furthermore, nucleoporin Nup82p, which plays a role in Msn5p-mediated transport, is necessary for efficient export of Ssa4p. In living cells, stress not only regulates Ssa4p localization, but also controls the distribution of Msn5p. Msn5p is concentrated in nuclei of unstressed cells, but appears in the cytoplasm upon exposure to ethanol, heat, starvation or severe oxidative stress. In addition, growth on non-fermentable carbon sources relocates a portion of Msn5p to the cytoplasm and leads to a partial nuclear accumulation of Ssa4p. Taken together, growth and stress conditions that localize the transporter Msn5p to the cytoplasm also induce the nuclear accumulation of its cargo Ssa4p.
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Affiliation(s)
- XinXin Quan
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, QC, H3G 1Y6, Canada
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33
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Matsumoto R, Akama K, Rakwal R, Iwahashi H. The stress response against denatured proteins in the deletion of cytosolic chaperones SSA1/2 is different from heat-shock response in Saccharomyces cerevisiae. BMC Genomics 2005; 6:141. [PMID: 16209719 PMCID: PMC1262714 DOI: 10.1186/1471-2164-6-141] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2005] [Accepted: 10/07/2005] [Indexed: 11/10/2022] Open
Abstract
Background A yeast strain lacking the two genes SSA1 and SSA2, which encode cytosolic molecular chaperones, acquires thermotolerance as well as the mild heat-shocked wild-type yeast strain. We investigated the genomic response at the level of mRNA expression to the deletion of SSA1/2 in comparison with the mild heat-shocked wild-type using cDNA microarray. Results Yeast cDNA microarray analysis revealed that genes involved in the stress response, including molecular chaperones, were up-regulated in a similar manner in both the ssa1/2 deletion mutant and the mild heat-shocked wild-type. Genes involved in protein synthesis were up-regulated in the ssa1/2 deletion mutant, but were markedly suppressed in the mild heat-shocked wild-type. The genes involved in ubiquitin-proteasome protein degradation were also up-regulated in the ssa1/2 deletion mutant, whereas the unfolded protein response (UPR) genes were highly expressed in the mild heat-shocked wild-type. RT-PCR confirmed that the genes regulating protein synthesis and cytosolic protein degradation were up-regulated in the ssa1/2 deletion mutant. At the translational level, more ubiquitinated proteins and proteasomes were detected in the ssa1/2 deletion mutant, than in the wild-type, confirming that ubiquitin-proteasome protein degradation was up-regulated by the deletion of SSA1/2. Conclusion These results suggest that the mechanism for rescue of denatured proteins in the ssa1/2 deletion mutant is different from that in the mild heat-shocked wild-type: Activated protein synthesis in the ssa1/2 deletion mutant supplies a deficiency of proteins by their degradation, whereas mild heat-shock induces UPR.
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Affiliation(s)
- Rena Matsumoto
- Graduate School of Science and Technology, Chiba University, 1-33 Yayoi-cho, Inage, Chiba, Chiba 263-8522, Japan
- International Patent Organism Depositary (IPOD), National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Kuniko Akama
- Graduate School of Science and Technology, Chiba University, 1-33 Yayoi-cho, Inage, Chiba, Chiba 263-8522, Japan
| | - Randeep Rakwal
- Human Stress Signal Research Center (HSSRC), AIST, Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Hitoshi Iwahashi
- Graduate School of Science and Technology, Chiba University, 1-33 Yayoi-cho, Inage, Chiba, Chiba 263-8522, Japan
- Human Stress Signal Research Center (HSSRC), AIST, Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
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Belanger KD, Gupta A, MacDonald KM, Ott CM, Hodge CA, Cole CM, Davis LI. Nuclear pore complex function in Saccharomyces cerevisiae is influenced by glycosylation of the transmembrane nucleoporin Pom152p. Genetics 2005; 171:935-47. [PMID: 16118201 PMCID: PMC1456851 DOI: 10.1534/genetics.104.036319] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The regulated transport of proteins across the nuclear envelope occurs through nuclear pore complexes (NPCs), which are composed of >30 different protein subunits termed nucleoporins. While some nucleoporins are glycosylated, little about the role of glycosylation in NPC activity is understood. We have identified loss-of-function alleles of ALG12, encoding a mannosyltransferase, as suppressors of a temperature-sensitive mutation in the gene encoding the FXFG-nucleoporin NUP1. We observe that nup1Delta cells import nucleophilic proteins more efficiently when ALG12 is absent, suggesting that glycosylation may influence nuclear transport. Conditional nup1 and nup82 mutations are partially suppressed by the glycosylation inhibitor tunicamycin, while nic96 and nup116 alleles are hypersensitive to tunicamycin treatment, further implicating glycosylation in NPC function. Because Pom152p is a glycosylated, transmembrane nucleoporin, we examined genetic interactions between pom152 mutants and nup1Delta. A nup1 deletion is lethal in combination with pom152Delta, as well as with truncations of the N-terminal and transmembrane regions of Pom152p. However, truncations of the N-glycosylated, lumenal domain of Pom152p and pom152 mutants lacking N-linked glycosylation sites are viable in combination with nup1Delta, suppress nup1Delta temperature sensitivity, and partially suppress the nuclear protein import defects associated with the deletion of NUP1. These data provide compelling evidence for a role for glycosylation in influencing NPC function.
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Affiliation(s)
- Kenneth D Belanger
- Department of Biology, Colgate University, Hamilton, New York 13346, USA
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35
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Dombek KM, Kacherovsky N, Young ET. The Reg1-interacting proteins, Bmh1, Bmh2, Ssb1, and Ssb2, have roles in maintaining glucose repression in Saccharomyces cerevisiae. J Biol Chem 2004; 279:39165-74. [PMID: 15220335 DOI: 10.1074/jbc.m400433200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
In Saccharomyces cerevisiae, a type 1 protein phosphatase complex composed of the Glc7 catalytic subunit and the Reg1 regulatory subunit represses expression of many glucose-regulated genes. Here we show that the Reg1-interacting proteins Bmh1, Bmh2, Ssb1, and Ssb2 have roles in glucose repression. Deleting both BMH genes causes partially constitutive ADH2 expression without significantly increasing the level of Adr1 protein, the major activator of ADH2 expression. Adr1 and Bcy1, the regulatory subunit of cAMP-dependent protein kinase, are both required for this effect indicating that constitutive expression in Deltabmh1Deltabmh2 cells uses the same activation pathway that operates in Deltareg1 cells. Deletion of both BMH genes and REG1 causes a synergistic relief from repression, suggesting that Bmh proteins also act independently of Reg1 during glucose repression. A two-hybrid interaction with the Bmh proteins was mapped to amino acids 187-232, a region of Reg1 that is conserved in different classes of fungi. Deleting this region partially releases SUC2 from glucose repression. This indicates a role for the Reg1-Bmh interaction in glucose repression and also suggests a broad role for Bmh proteins in this process. An in vivo Reg1-Bmh interaction was confirmed by copurification of Bmh proteins with HA(3)-TAP-tagged Reg1. The nonconventional heat shock proteins Ssb1 and Ssb2 are also copurified with HA(3)-TAP-tagged Reg1. Deletion of both SSB genes modestly decreases repression of ADH2 expression in the presence of glucose, suggesting that Ssb proteins, perhaps through their interaction with Reg1, play a minor role in glucose repression.
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Affiliation(s)
- Kenneth M Dombek
- Department of Biochemistry, University of Washington, Seattle, Washington 98195-7350, USA.
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36
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Quan X, Rassadi R, Rabie B, Matusiewicz N, Stochaj U. Regulated nuclear accumulation of the yeast hsp70 Ssa4p in ethanol-stressed cells is mediated by the N-terminal domain, requires the nuclear carrier Nmd5p and protein kinase C. FASEB J 2004; 18:899-901. [PMID: 15001563 DOI: 10.1096/fj.03-0947fje] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cytoplasmic proteins of the hsp70/hsc70 family redistribute in cells that have been exposed to stress. As such, the hsp70 Ssa4p of the budding yeast S. cerevisiae accumulates in nuclei when cells are treated with ethanol, whereas classical nuclear import is inhibited under these conditions. The N-terminal domain of Ssa4p, which is lacking a classical NLS, mediates nuclear accumulation upon ethanol exposure. Concentration of the Ssa4p N-terminal segment in nuclei is reversible, as the protein relocates to the cytoplasm when cells recover. Mutant analysis demonstrates that the small GTPase Gsp1p and GTPase-modulating factors are required to accumulate Ssa4p in nuclei upon ethanol stress. Moreover, we have identified the importin-beta family member Nmd5p as the nuclear carrier for Ssa4p. Ethanol treatment significantly increases the formation of import complexes containing Nmd5p and the N-terminal Ssa4p domain. Likewise, docking of the carrier Nmd5p at the nuclear pore is enhanced by ethanol. Furthermore, we show that the stressed-induced nuclear accumulation of Ssa4p depends on signaling through protein kinase C and requires sensors of the cell integrity pathway.
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Affiliation(s)
- Xinxin Quan
- Physiology Department, McGill University, Montreal, PQ, Canada
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Tsukahara F, Maru Y. Identification of Novel Nuclear Export and Nuclear Localization-related Signals in Human Heat Shock Cognate Protein 70. J Biol Chem 2004; 279:8867-72. [PMID: 14684748 DOI: 10.1074/jbc.m308848200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Heat shock cognate protein 70 (Hsc70) serves nuclear transport of several proteins as a molecular chaperone. We have recently identified a novel variant of human Hsc70, heat shock cognate protein 54 (Hsc54), that lacks amino acid residues 464-616 in the protein binding and variable domains of Hsc70. In the present study, we examined nucleocytoplasmic localization of Hsc70 and Hsc54 by using green fluorescent protein (GFP) fusions. GFP-Hsc70 is localized in both the cytoplasm and the nucleus at 37 degrees C and accumulated into the nucleolus/nucleus after heat shock, whereas GFP-Hsc54 always remained exclusively in the cytoplasm under these conditions. Mutation studies indicated that 20 amino acid residues of nuclear localization-related signals, which are missing in Hsc54 but are retained in Hsc70, are required for proper nuclear localization of Hsc70. We further found that Hsc54 contains a functional leucine-rich nuclear export signal (NES, (394)LDVTPLSL(401)) which is differently situated from the previously proposed NES in Saccharomyces cerevisiae Ssb1p. The cytoplasmic localization of Hsc54 was impaired by a mutation in NES as well as by a nuclear export inhibitor, leptomycin B, suggesting that Hsc54 is actively exported from the nucleus to the cytoplasm through a CRM1-dependent mechanism. In contrast, the nucleocytoplasmic localization of Hsc70 was not affected by the same mutation of NES or leptomycin B. These results suggest that the nuclear localization-related signal could functionally mask NES leading to prolonged retention of Hsc70 in the nucleus. An additional mechanism for unmasking the NES may regulate nucleocytoplasmic trafficking of Hsc70.
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Affiliation(s)
- Fujiko Tsukahara
- Department of Pharmacology, Tokyo Women's Medical University, School of Medicine, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan.
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Cernila B, Cresnar B, Breskvar K. Molecular characterization of a ribosome-associated Hsp70-homologous gene from Rhizopus nigricans. ACTA ACUST UNITED AC 2003; 1629:109-13. [PMID: 14522086 DOI: 10.1016/j.bbaexp.2003.08.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A ribosome-associated Hsp70-homologous gene (Rnssb-1) was isolated from the genomic library of the filamentous zygomycete fungus Rhizopus nigricans. The nucleotide sequence of a genomic clone encoded the N-terminal part of a protein with high similarity to the yeast SSB ribosome-associated chaperones. The missing 3' end of the gene was obtained by 3' RACE. The Northern blot analysis showed that the Rnssb-1 gene is constitutively expressed and is not induced upon heat shock at 37 degrees C. The primary structure analyses revealed that the coding region of the Rnssb-1 gene is interrupted by at least four introns. Their splicing was not inhibited by exposure of the organism to heat shock as proven by RT-PCR. A Southern blot analysis of R. nigricans genomic DNA confirmed the presence of two additional gene copies of ribosome-associated Hsp70 genes in the fungal genome.
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Affiliation(s)
- Bostjan Cernila
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, Ljubljana, SI-1000, Slovenia
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39
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Shulga N, Goldfarb DS. Binding dynamics of structural nucleoporins govern nuclear pore complex permeability and may mediate channel gating. Mol Cell Biol 2003; 23:534-42. [PMID: 12509452 PMCID: PMC151542 DOI: 10.1128/mcb.23.2.534-542.2003] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nuclear pore complex (NPC) is a permeable sieve that can dilate to facilitate the bidirectional translocation of a wide size range of receptor-cargo complexes. The binding of receptors to FG nucleoporin docking sites triggers channel gating by an unknown mechanism. Previously, we used deoxyglucose and chilling treatments to implicate Nup170p and Nup188p in the control of NPC sieving in Saccharomyces cerevisiae. Here, we report that aliphatic alcohols increase the permeability of wild-type and nup170Delta NPCs. In conjunction with increases in permeability, aliphatic alcohols, deoxyglucose, and chilling trigger the reversible dissociation of several nucleoporins from nup170Delta NPCs. These results are consistent with the hypothesis that NPC gating occurs when molecular latches composed of FG repeats and structural nucleoporins dissociate.
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Affiliation(s)
- Nataliya Shulga
- Department of Biology, University of Rochester, Rochester, New York 14627, USA
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Suzuki T, Kumamoto H, Ooya K, Motegi K. Expression of inducible nitric oxide synthase and heat shock proteins in periapical inflammatory lesions. J Oral Pathol Med 2002; 31:488-93. [PMID: 12220357 DOI: 10.1034/j.1600-0714.2002.00016.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND The mechanisms responsible for activation and proliferation of lining epithelium involved in inflammatory processes in periapical inflammatory lesions remain unclear. In this study, the expression and distribution of inducible nitric oxide synthase (iNOS) and heat shock proteins (HSPs) were immunohistochemically investigated in periapical inflammatory lesions. METHODS Control specimens of periodontal ligaments including Malassez epithelial rests from seven teeth and periapical inflammatory lesions (15 apical granulomas (AGs), 16 radicular cysts (RCs), and 10 residual radicular cysts (RRCs)) were prepared and examined by the standard streptavidin-biotin peroxidase complex method using anti-iNOS rabbit polyclonal antiserum, and anti-HSP27, -HSP60, -HSP70 mouse monoclonal antibodies. RESULTS Immunoreactivity for iNOS was detected in macrophages, lymphocytes, and endothelial cells of granulation tissue and in lining epithelium of periapical inflammatory lesions. Malassez epithelial rests showed no or slight staining for iNOS. The epithelial staining intensity of iNOS in RCs was greater than that in Malassez epithelial rests and RRCs. Immunoreactivity for HSP27 was recognized in inflammatory cells, endothelial cells and lining epithelium of periapical inflammatory lesions and in Malassez epithelial rests. HSP60 was detected in some lymphocytes of granulation tissue and in lining epithelium of periapical inflammatory lesions, whereas Malassez epithelial rests showed no staining for HSP60. Epithelial HSP60 reactivity was more intense in RCs than in RRCs. HSP70 was expressed in lymphocytes, endothelial cells and lining epithelium of periapical inflammatory lesions and in Malassez epithelial rests. The staining intensity of HSP70 in Malassez epithelial rests was slightly lower than that in lining epithelium of RCs and RRCs. CONCLUSIONS These data demonstrate that the expressions of iNOS, HSP60, and HSP70 are involved in inflammatory processes and might play a role in the activation and proliferation of lining epithelium, leading to progression of periapical inflammatory lesions.
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Affiliation(s)
- Takahiro Suzuki
- Department of Oro-Maxillofacial Surgical Science, Division of Maxillofacial and Plastic Surgery, Tohoku University Graduate School of Dentistry, Sendai, Japan.
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41
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Hon T, Lee HC, Hach A, Johnson JL, Craig EA, Erdjument-Bromage H, Tempst P, Zhang L. The Hsp70-Ydj1 molecular chaperone represses the activity of the heme activator protein Hap1 in the absence of heme. Mol Cell Biol 2001; 21:7923-32. [PMID: 11689685 PMCID: PMC99961 DOI: 10.1128/mcb.21.23.7923-7932.2001] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Saccharomyces cerevisiae, heme directly mediates the effects of oxygen on transcription through the heme activator protein Hap1. In the absence of heme, Hap1 is bound by at least four cellular proteins, including Hsp90 and Ydj1, forming a higher-order complex, termed HMC, and its activity is repressed. Here we purified the HMC and showed by mass spectrometry that two previously unidentified major components of the HMC are the Ssa-type Hsp70 molecular chaperone and Sro9 proteins. In vivo functional analysis, combined with biochemical analysis, strongly suggests that Ssa proteins are critical for Hap1 repression in the absence of heme. Ssa may repress the activities of both Hap1 DNA-binding and activation domains. The Ssa cochaperones Ydj1 and Sro9 appear to assist Ssa in Hap1 repression, and only Ydj1 residues 1 to 172 containing the J domain are required for Hap1 repression. Our results suggest that Ssa-Ydj1 and Sro9 act together to mediate Hap1 repression in the absence of heme and that molecular chaperones promote heme regulation of Hap1 by a mechanism distinct from the mechanism of steroid signaling.
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Affiliation(s)
- T Hon
- Department of Biochemistry, NYU School of Medicine, New York, New York 10016, USA
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42
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Pfund C, Huang P, Lopez-Hoyo N, Craig EA. Divergent functional properties of the ribosome-associated molecular chaperone Ssb compared with other Hsp70s. Mol Biol Cell 2001; 12:3773-82. [PMID: 11739779 PMCID: PMC60754 DOI: 10.1091/mbc.12.12.3773] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Ssbs of Saccharomyces cerevisiae are ribosome-associated molecular chaperones, which can be cross-linked to nascent polypeptide chains. Because Ssbs are members of a divergent subclass of Hsp70s found thus far only in fungi, we asked if the structural requirements for in vivo function were similar to those of "classic" Hsp70s. An intact peptide-binding domain is essential and an alteration of a conserved residue in the peptide-binding cleft (V442) affects function. However, Ssb tolerates a number of alterations in the peptide-binding cleft, revealing a high degree of flexibility in its functional requirements. Because binding of Ssb to peptide substrates in vitro was undetectable, we assessed the importance of substrate binding using the chimera BAB, in which the peptide binding domain of Ssb is exchanged for the analogous domain of the more "classical" Hsp70, Ssa. BAB, which binds peptide substrates in vitro, can substitute for Ssb in vivo. Alteration of a residue in the peptide-binding cleft of BAB creates a protein with a reduced affinity for peptide and altered ribosome binding that is unable to substitute for Ssb in vivo. These results indicate that Ssb's ability to bind unfolded polypeptides is likely critical for its function. This binding accounts, in part, for its stable interaction with translating ribosomes, even although it has a low affinity for peptides that detectably bind to other Hsp70s in vitro. These unusual properties may allow Ssb to function efficiently as a chaperone for ribosome-bound nascent chains.
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Affiliation(s)
- C Pfund
- Department of Biomolecular Chemistry, University of Wisconsin, Madison, WI 53706, USA
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43
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Franke J, Reimann B, Hartmann E, Köhlerl M, Wiedmann B. Evidence for a nuclear passage of nascent polypeptide-associated complex subunits in yeast. J Cell Sci 2001; 114:2641-8. [PMID: 11683391 DOI: 10.1242/jcs.114.14.2641] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nascent polypeptide-associated complex (NAC) has been found quantitatively associated with ribosomes in the cytosol by means of cell fractionation or fluorescence microscopy. There have been reports, however, that single NAC subunits may be involved in transcriptional regulation. We reasoned that the cytosolic location might only reflect a steady state equilibrium and therefore investigated the yeast NAC proteins for their ability to enter the nucleus. We found that single subunits of yeast NAC can indeed be transported into the nucleus and that this transport is an active process depending on different nuclear import factors. Translocation into the nucleus was only observed when binding to ribosomes was inhibited. We identified a domain of the ribosome-binding NAC subunit essential for nuclear import via the importin Kap123p/Pse1p-dependent import route. We hypothesize that newly translated NAC proteins travel into the nucleus to bind stoichiometrically to ribosomal subunits and then leave the nucleus together with these subunits to concentrate in the cytosol.
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Affiliation(s)
- J Franke
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
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44
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Chughtai ZS, Rassadi R, Matusiewicz N, Stochaj U. Starvation promotes nuclear accumulation of the hsp70 Ssa4p in yeast cells. J Biol Chem 2001; 276:20261-6. [PMID: 11279056 DOI: 10.1074/jbc.m100364200] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nuclear import of proteins that are too large to passively enter the nucleus requires soluble factors, energy, and a nuclear localization signal (NLS). Nuclear protein transport can be regulated, and different forms of stress affect nucleocytoplasmic trafficking. As such, import of proteins containing a classical NLS is inhibited in starving yeast cells. In contrast, the hsp70 Ssa4p concentrates in nuclei upon starvation. Nuclear concentration of Ssa4p in starving cells is reversible, and transfer of stationary phase cells to fresh medium induces Ssa4p nuclear export. This export reaction represents an active process that is sensitive to oxidative stress. In starving cells, the N-terminal domain of Ssa4p mediates Ssa4p nuclear accumulation, and a short hydrophobic sequence, termed Star (for starvation), is sufficient to localize the reporter proteins green fluorescent protein or beta-galactosidase to nuclei. To determine whether nuclear accumulation of Star-beta-galactosidase depends on a specific nuclear carrier, we have analyzed its distribution in mutant yeast strains that carry a deletion of a single beta-importin gene. With this assay we have identified Nmd5p as a beta-importin required to concentrate Star-beta-galactosidase in nuclei when cells enter stationary phase.
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Affiliation(s)
- Z S Chughtai
- Department of Physiology, McGill University, Montreal, Province of Quebec H3G 1Y6, Canada
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45
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Nakai Y, Nakai M, Hayashi H, Kagamiyama H. Nuclear localization of yeast Nfs1p is required for cell survival. J Biol Chem 2001; 276:8314-20. [PMID: 11110795 DOI: 10.1074/jbc.m007878200] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Saccharomyces cerevisiae Nfs1p is mainly found in the mitochondrial matrix and has been shown to participate in iron-sulfur cluster assembly. We show here that Nfs1p contains a potential nuclear localization signal, RRRPR, in its mature part. When this sequence was mutated to RRGSR, the mutant protein could not restore cell growth under chromosomal NFS1-depleted conditions. However, this mutation did not affect the function of Nfs1p in biogenesis of mitochondrial iron-sulfur proteins. The growth defect of the mutant was complemented by simultaneous expression of the mature Nfs1p, which contains the intact nuclear localization signal but lacks its mitochondrial-targeting presequence. These results suggest that a fraction of Nfs1p is localized in the nucleus and is essential for cell viability.
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Affiliation(s)
- Y Nakai
- Department of Biochemistry, Osaka Medical College, Takatsuki, Osaka 569-8686 Japan.
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46
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Maurer P, Redd M, Solsbacher J, Bischoff FR, Greiner M, Podtelejnikov AV, Mann M, Stade K, Weis K, Schlenstedt G. The nuclear export receptor Xpo1p forms distinct complexes with NES transport substrates and the yeast Ran binding protein 1 (Yrb1p). Mol Biol Cell 2001; 12:539-49. [PMID: 11251069 PMCID: PMC30962 DOI: 10.1091/mbc.12.3.539] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2000] [Revised: 10/18/2000] [Accepted: 01/09/2001] [Indexed: 11/11/2022] Open
Abstract
Xpo1p (Crm1p) is the nuclear export receptor for proteins containing a leucine-rich nuclear export signal (NES). Xpo1p, the NES-containing protein, and GTP-bound Ran form a complex in the nucleus that translocates across the nuclear pore. We have identified Yrb1p as the major Xpo1p-binding protein in Saccharomyces cerevisiae extracts in the presence of GTP-bound Gsp1p (yeast Ran). Yrb1p is cytoplasmic at steady-state but shuttles continuously between the cytoplasm and the nucleus. Nuclear import of Yrb1p is mediated by two separate nuclear targeting signals. Export from the nucleus requires Xpo1p, but Yrb1p does not contain a leucine-rich NES. Instead, the interaction of Yrb1p with Xpo1p is mediated by Gsp1p-GTP. This novel type of export complex requires the acidic C-terminus of Gsp1p, which is dispensable for the binding to importin beta-like transport receptors. A similar complex with Xpo1p and Gsp1p-GTP can be formed by Yrb2p, a relative of Yrb1p predominantly located in the nucleus. Yrb1p also functions as a disassembly factor for NES/Xpo1p/Gsp1p-GTP complexes by displacing the NES protein from Xpo1p/Gsp1p. This Yrb1p/Xpo1p/Gsp1p complex is then completely dissociated after GTP hydrolysis catalyzed by the cytoplasmic GTPase activating protein Rna1p.
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Affiliation(s)
- P Maurer
- Medizinische Biochemie und Molekularbiologie, Universität des Saarlandes, 66421 Homburg, Germany
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47
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Abstract
SUMMARY In recent years, our understanding of macromolecular transport processes across the nuclear envelope has grown dramatically, and a large number of soluble transport receptors mediating either nuclear import or nuclear export have been identified. Most of these receptors belong to one large family of proteins, all of which share homology with the protein import receptor importin beta (also named karyopherin beta). Members of this family have been classified as importins or exportins on the basis of the direction they carry their cargo. To date, the family includes 14 members in the yeast Saccharomyces cerevisiae and at least 22 members in humans. Importins and exportins are regulated by the small GTPase Ran, which is thought to be highly enriched in the nucleus in its GTP-bound form. Importins recognize their substrates in the cytoplasm and transport them through nuclear pores into the nucleus. In the nucleoplasm, RanGTP binds to importins, inducing the release of import cargoes. In contrast, exportins interact with their substrates only in the nucleus in the presence of RanGTP and release them after GTP hydrolysis in the cytoplasm, causing disassembly of the export complex. Thus, common features of all importin-beta-like transport factors are their ability to shuttle between the nucleus and the cytoplasm, their interaction with RanGTP as well as their ability to recognize specific transport substrates.
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Affiliation(s)
- Anne-Christine Ström
- Department of Molecular and Cellular Biology, University of California, Berkeley, CA 94720-3200, USA
| | - Karsten Weis
- Department of Molecular and Cellular Biology, University of California, Berkeley, CA 94720-3200, USA
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48
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Shulga N, Mosammaparast N, Wozniak R, Goldfarb DS. Yeast nucleoporins involved in passive nuclear envelope permeability. J Cell Biol 2000; 149:1027-38. [PMID: 10831607 PMCID: PMC2174828 DOI: 10.1083/jcb.149.5.1027] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The vertebrate nuclear pore complex (NPC) harbors an approximately 10-nm diameter diffusion channel that is large enough to admit 50-kD polypeptides. We have analyzed the permeability properties of the Saccharomyces cerevisiae nuclear envelope (NE) using import (NLS) and export (NES) signal-containing green fluorescent protein (GFP) reporters. Compared with wild-type, passive export rates of a classical karyopherin/importin (Kap) Kap60p/Kap95p-targeted NLS-GFP reporter (cNLS-GFP) were significantly faster in nup188-Delta and nup170-Delta cells. Similar results were obtained using two other NLS-GFP reporters, containing either the Kap104p-targeted Nab2p NLS (rgNLS) or the Kap121p-targeted Pho4p NLS (pNLS). Elevated levels of Hsp70 stimulated cNLS-GFP import, but had no effect on the import of rgNLS-GFP. Thus, the role of Hsp70 in NLS-directed import may be NLS- or targeting pathway-specific. Equilibrium sieving limits for the diffusion channel were assessed in vivo using NES-GFP reporters of 36-126 kD and were found to be greater than wild-type in nup188-Delta and nup170-Delta cells. We propose that Nup170p and Nup188p are involved in establishing the functional resting diameter of the NPC's central transport channel.
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Affiliation(s)
- Nataliya Shulga
- Department of Biology, University of Rochester, Rochester, New York 14627
| | - Nima Mosammaparast
- Department of Biology, University of Rochester, Rochester, New York 14627
| | - Richard Wozniak
- Department of Cell Biology, University of Alberta, Alberta, Canada T6G 2H7
| | - David S. Goldfarb
- Department of Biology, University of Rochester, Rochester, New York 14627
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49
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Tartakoff AM, Lichtenstein M, Nanduri J, Tsao HM. Review: dynamic stability of the interphase nucleus in health and disease. J Struct Biol 2000; 129:144-58. [PMID: 10806065 DOI: 10.1006/jsbi.2000.4225] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Ongoing export of newly synthesized RNAs, as well as control of transcriptional activity, involves dynamic nucleocytoplasmic transport of proteins. Some proteins that shuttle reside primarily in the nucleus while others are concentrated in the cytoplasm. Moreover, some proteins shuttle continuously, while others shuttle only once. A third group is stimulated to relocate either into or out of the nucleus as a result of interruption of shuttling. In addition to these protein-specific events, several physiological stimuli have global effects on nucleocytoplasmic transport. In related events, selected proteins move between distinct sites in the nucleoplasm, others enter and leave the nucleolus, and still others transit between the nuclear envelope and cytoplasmic membranes. These multiple dynamic distributions provide numerous opportunities for precise communication between spatially distant sites in the cell.
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Affiliation(s)
- A M Tartakoff
- Pathology Department, Cell Biology Program, Case Western Reserve University School of Medicine, 2085 Adelbert Road, Cleveland, Ohio, 44106, USA
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50
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Hallstrom TC, Moye-Rowley WS. Hyperactive forms of the Pdr1p transcription factor fail to respond to positive regulation by the hsp70 protein Pdr13p. Mol Microbiol 2000; 36:402-13. [PMID: 10792726 DOI: 10.1046/j.1365-2958.2000.01858.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Multidrug resistance in Saccharomyces cerevisiae is commonly associated with the overproduction of ATP-binding cassette transporter proteins such as Pdr5p or Yor1p. The Cys6-Zn(II)2 cluster-containing transcription factors Pdr1p and Pdr3p are key regulators of expression of these pleiotropic drug resistance (PDR) loci. Previous experiments have demonstrated that the Hsp70 protein encoded by the PDR13 gene is a positive regulator of Pdr1p function. We have examined the mechanism underlying the control of Pdr1p by Pdr13p. Expression of deletion, insertion and amino acid substitution mutant variants of Pdr1p suggest that the centre region of the transcription factor is the target for Pdr13p-mediated positive regulation. Immunological and fusion protein analyses demonstrate that Pdr13p is located in the cytoplasm, while Pdr1p is found in the nucleus. Biochemical fractionation experiments indicate that Pdr13p is associated with a high-molecular-weight complex and suggest the association of some fraction of Pdr13p with ribosomes.
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Affiliation(s)
- T C Hallstrom
- Molecular Biology Program and the Department of Physiology and Biophysics, 5-430 Bowen Science Building, University of Iowa, Iowa City, IA 52242, USA
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