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Kha CX, Nava I, Tseng KAS. V-ATPase Regulates Retinal Progenitor Cell Proliferation During Eye Regrowth in Xenopus. J Ocul Pharmacol Ther 2023; 39:499-508. [PMID: 36867156 PMCID: PMC10616942 DOI: 10.1089/jop.2022.0085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 11/29/2022] [Indexed: 03/04/2023] Open
Abstract
Purpose: The induction of retinal progenitor cell (RPC) proliferation is a strategy that holds promise for alleviating retinal degeneration. However, the mechanisms that can stimulate RPC proliferation during repair remain unclear. Xenopus tailbud embryos successfully regrow functional eyes within 5 days after ablation, and this process requires increased RPC proliferation. This model facilitates identification of mechanisms that can drive in vivo reparative RPC proliferation. This study assesses the role of the essential H+ pump, V-ATPase, in promoting stem cell proliferation. Methods: Pharmacological and molecular loss of function studies were performed to determine the requirement for V-ATPase during embryonic eye regrowth. The resultant eye phenotypes were examined using histology and antibody markers. Misexpression of a yeast H+ pump was used to test whether the requirement for V-ATPase in regrowth is dependent on its H+ pump function. Results: V-ATPase inhibition blocked eye regrowth. Regrowth-incompetent eyes resulting from V-ATPase inhibition contained the normal complement of tissues but were much smaller. V-ATPase inhibition caused a significant reduction in reparative RPC proliferation but did not alter differentiation and patterning. Modulation of V-ATPase activity did not affect apoptosis, a process known to be required for eye regrowth. Finally, increasing H+ pump activity was sufficient to induce regrowth. Conclusions: V-ATPase is required for eye regrowth. These results reveal a key role for V-ATPase in activating regenerative RPC proliferation and expansion during successful eye regrowth.
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Affiliation(s)
- Cindy X. Kha
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada, USA
| | - Iris Nava
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada, USA
| | - Kelly Ai-Sun Tseng
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada, USA
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2
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Zhang QY, Gu KD, Wang JH, Yu JQ, Wang XF, Zhang S, You CX, Hu DG, Hao YJ. BTB-BACK-TAZ domain protein MdBT2-mediated MdMYB73 ubiquitination negatively regulates malate accumulation and vacuolar acidification in apple. HORTICULTURE RESEARCH 2020; 7:151. [PMID: 32944259 PMCID: PMC7468283 DOI: 10.1038/s41438-020-00384-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 07/14/2020] [Accepted: 07/27/2020] [Indexed: 05/19/2023]
Abstract
As an important primary metabolite, malate plays a key role in regulating osmotic pressure, pH homeostasis, stress tolerance, and fruit quality of apple. The R2R3-MYB transcription factor (TF) MdMYB73 was identified as a protein that plays a critical role in determining malate accumulation and vacuolar acidification by directly regulating the transcription of aluminum-activated malate transporter 9 (MdALMT9), vacuolar ATPase subunit A (MdVHA-A), and vacuolar pyrophosphatase 1 (MdVHP1) in apple. In addition, the bHLH TF MdCIbHLH1 interacts with MdMYB73 and enhances the transcriptional activity of MdMYB73. Our previous studies demonstrated that the BTB-BACK-TAZ domain protein MdBT2 can degrade MdCIbHLH1 to influence malate accumulation and vacuolar acidification. However, the potential upstream regulators of MdMYB73 are currently unknown. In this study, we found that MdBT2 directly interacts with and degrades MdMYB73 through the ubiquitin/26S proteasome pathway to regulate malate accumulation and vacuolar acidification. A series of functional assays with apple calli and fruit showed that MdBT2 controls malate accumulation and vacuolar acidification in an MdMYB73-dependent manner. Overall, our findings shed light on the mechanism by which the BTB-BACK-TAZ domain protein MdBT2 regulates malate accumulation and vacuolar acidification by targeting MdMYB73 and MdCIbHLH1 for ubiquitination in apple. This information may help guide traditional breeding programs and fruit tree molecular breeding, and lead to improvements in fruit quality and stress tolerance.
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Affiliation(s)
- Quan-Yan Zhang
- National Key Laboratory of Crop Biology, Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018 China
| | - Kai-Di Gu
- National Key Laboratory of Crop Biology, Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018 China
| | - Jia-Hui Wang
- National Key Laboratory of Crop Biology, Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018 China
| | - Jian-Qiang Yu
- National Key Laboratory of Crop Biology, Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018 China
| | - Xiao-Fei Wang
- National Key Laboratory of Crop Biology, Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018 China
| | - Shuai Zhang
- College of Chemistry and Material Science, Shandong Agricultural University, Tai-An, Shandong 271018 China
| | - Chun-Xiang You
- National Key Laboratory of Crop Biology, Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018 China
| | - Da-Gang Hu
- National Key Laboratory of Crop Biology, Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018 China
| | - Yu-Jin Hao
- National Key Laboratory of Crop Biology, Shandong Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018 China
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3
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Collins MP, Forgac M. Regulation and function of V-ATPases in physiology and disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183341. [PMID: 32422136 DOI: 10.1016/j.bbamem.2020.183341] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/30/2020] [Accepted: 05/03/2020] [Indexed: 02/07/2023]
Abstract
The vacuolar H+-ATPases (V-ATPases) are essential, ATP-dependent proton pumps present in a variety of eukaryotic cellular membranes. Intracellularly, V-ATPase-dependent acidification functions in such processes as membrane traffic, protein degradation, autophagy and the coupled transport of small molecules. V-ATPases at the plasma membrane of certain specialized cells function in such processes as bone resorption, sperm maturation and urinary acidification. V-ATPases also function in disease processes such as pathogen entry and cancer cell invasiveness, while defects in V-ATPase genes are associated with disorders such as osteopetrosis, renal tubular acidosis and neurodegenerative diseases. This review highlights recent advances in our understanding of V-ATPase structure, mechanism, function and regulation, with an emphasis on the signaling pathways controlling V-ATPase assembly in mammalian cells. The role of V-ATPases in cancer and other human pathologies, and the prospects for therapeutic intervention, are also discussed.
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Affiliation(s)
- Michael P Collins
- Cell, Molecular and Developmental Biology, Tufts University Graduate School of Biomedical Sciences, United States of America
| | - Michael Forgac
- Cell, Molecular and Developmental Biology, Tufts University Graduate School of Biomedical Sciences, United States of America; Dept. of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111, United States of America.
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4
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Jia D, Shen F, Wang Y, Wu T, Xu X, Zhang X, Han Z. Apple fruit acidity is genetically diversified by natural variations in three hierarchical epistatic genes: MdSAUR37, MdPP2CH and MdALMTII. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 95:427-443. [PMID: 29750477 DOI: 10.1111/tpj.13957] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 04/13/2018] [Accepted: 04/17/2018] [Indexed: 05/21/2023]
Abstract
Many efforts have been made to map quantitative trait loci (QTLs) to facilitate practical marker-assisted selection (MAS) in plants. In the present study, using MapQTL and BSA-seq (bulk segregant analysis using next generation sequencing) with two independent pedigree-based populations, we identified four major genome-wide QTLs responsible for apple fruit acidity. Candidate genes were screened in major QTL regions, and three functional gene markers, including a non-synonymous A/G single-nucleotide polymorphism (SNP) in the coding region of MdPP2CH, a 36-bp insertion in the promoter of MdSAUR37 and a previously reported SNP in MdALMTII, were validated to influence the malate content of apple fruits. In addition, MdPP2CH inactivated three vacuolar H+ -ATPases (MdVHA-A3, MdVHA-B2 and MdVHA-D2) and one aluminium-activated malate transporter (MdALMTII) via dephosphorylation and negatively influenced fruit malate accumulation. The dephosphotase activity of MdPP2CH was suppressed by MdSAUR37, which implied a higher hierarchy of genetic interaction. Therefore, the MdSAUR37/MdPP2CH/MdALMTII chain cascaded hierarchical epistatic genetic effects to precisely determine apple fruit malate content. An A/G SNP (-1010) on the MdMYB44 promoter region from a major QTL (qtl08.1) was closely associated with fruit malate content. The predicted phenotype values (PPVs) were estimated using the tentative genotype values of the gene markers, and the PPVs were significantly correlated with the observed phenotype values. Our findings provide an insight into plant genome-based selection in apples and will aid in conducting research to understand the fundamental physiological basis of quantitative genetics.
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Affiliation(s)
- Dongjie Jia
- Institute for Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, China
| | - Fei Shen
- Institute for Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, China
| | - Yi Wang
- Institute for Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, China
| | - Ting Wu
- Institute for Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, China
| | - Xuefeng Xu
- Institute for Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, China
| | - Xinzhong Zhang
- Institute for Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, China
| | - Zhenhai Han
- Institute for Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, China
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5
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Sharma S, Oot RA, Wilkens S. MgATP hydrolysis destabilizes the interaction between subunit H and yeast V 1-ATPase, highlighting H's role in V-ATPase regulation by reversible disassembly. J Biol Chem 2018; 293:10718-10730. [PMID: 29754144 DOI: 10.1074/jbc.ra118.002951] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 04/22/2018] [Indexed: 01/01/2023] Open
Abstract
Vacuolar H+-ATPases (V-ATPases; V1Vo-ATPases) are rotary-motor proton pumps that acidify intracellular compartments and, in some tissues, the extracellular space. V-ATPase is regulated by reversible disassembly into autoinhibited V1-ATPase and Vo proton channel sectors. An important player in V-ATPase regulation is subunit H, which binds at the interface of V1 and Vo H is required for MgATPase activity in holo-V-ATPase but also for stabilizing the MgADP-inhibited state in membrane-detached V1 However, how H fulfills these two functions is poorly understood. To characterize the H-V1 interaction and its role in reversible disassembly, we determined binding affinities of full-length H and its N-terminal domain (HNT) for an isolated heterodimer of subunits E and G (EG), the N-terminal domain of subunit a (aNT), and V1 lacking subunit H (V1ΔH). Using isothermal titration calorimetry (ITC) and biolayer interferometry (BLI), we show that HNT binds EG with moderate affinity, that full-length H binds aNT weakly, and that both H and HNT bind V1ΔH with high affinity. We also found that only one molecule of HNT binds V1ΔH with high affinity, suggesting conformational asymmetry of the three EG heterodimers in V1ΔH. Moreover, MgATP hydrolysis-driven conformational changes in V1 destabilized the interaction of H or HNT with V1ΔH, suggesting an interplay between MgADP inhibition and subunit H. Our observation that H binding is affected by MgATP hydrolysis in V1 points to H's role in the mechanism of reversible disassembly.
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Affiliation(s)
- Stuti Sharma
- From the Department of Biochemistry and Molecular Biology, State University of New York (SUNY) Upstate Medical University, Syracuse, New York 13210
| | - Rebecca A Oot
- From the Department of Biochemistry and Molecular Biology, State University of New York (SUNY) Upstate Medical University, Syracuse, New York 13210
| | - Stephan Wilkens
- From the Department of Biochemistry and Molecular Biology, State University of New York (SUNY) Upstate Medical University, Syracuse, New York 13210
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Hu DG, Sun CH, Sun MH, Hao YJ. MdSOS2L1 phosphorylates MdVHA-B1 to modulate malate accumulation in response to salinity in apple. PLANT CELL REPORTS 2016; 35:705-18. [PMID: 26687966 DOI: 10.1007/s00299-015-1914-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 10/26/2015] [Accepted: 11/26/2015] [Indexed: 05/22/2023]
Abstract
Salt-induced phosphorylation of MdVHA-B1 protein was mediated by MdSOS2L1 protein kinase, and thereby increasing malate content in apple. Salinity is an important environmental factor that influences malate accumulation in apple. However, the molecular mechanism by which salinity regulates this process is poorly understood. In this work, we found that MdSOS2L1, a novel AtSOS2-LIKE protein kinase, interacts with V-ATPase subunit MdVHA-B1. Furthermore, MdSOS2L1 directly phosphorylates MdVHA-B1 at Ser(396) site to modulate malate accumulation in response to salt stress. Meanwhile, a series of transgenic analyses in apple calli showed that the MdSOS2L1-MdVHAB1 pathway was involved in the regulation of malate accumulation. Finally, a viral vector-based transformation approach demonstrated that the MdSOS2L1-MdVHAB1 pathway also modulated malate accumulation in apple fruits with or without salt stress. Collectively, our findings provide a new insight into the mechanism by which MdSOS2L1 phosphorylates MdVHA-B1 to modulate malate accumulation in response to salinity in apple.
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Affiliation(s)
- Da-Gang Hu
- State Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-an, 271018, Shandong, China
| | - Cui-Hui Sun
- State Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-an, 271018, Shandong, China
| | - Mei-Hong Sun
- State Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-an, 271018, Shandong, China
| | - Yu-Jin Hao
- State Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-an, 271018, Shandong, China.
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7
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Fu KY, Guo WC, Lü FG, Liu XP, Li GQ. Response of the vacuolar ATPase subunit E to RNA interference and four chemical pesticides in Leptinotarsa decemlineata (Say). PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2014; 114:16-23. [PMID: 25175645 DOI: 10.1016/j.pestbp.2014.07.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 07/20/2014] [Accepted: 07/20/2014] [Indexed: 06/03/2023]
Abstract
Vacuolar-type H(+)-ATPases (vATPases) are localized in the apical membranes of nearly all epithelial tissues of insects, energize the membranes to absorb and/or secrete ions and fluids, and play essential roles in many physiological functions. Here we cloned and characterized a 1041-bp full-length vATPase subunit E cDNA (named as LdATPaseE) that encoded a 226-amino acid protein in Leptinotarsa decemlineata. LdATPaseE mRNA levels were constantly increased from egg to the third- and fourth-instar stages, dropped in wandering and pupal stages and were elevated again in the adult stage. It was highly expressed in ileum and rectum, moderately expressed in Malpighian tubules, midgut and foregut, and lowly expressed in fat body, ventral ganglion, epidermis and haemocytes in the fourth instars. After continuously ingested double-stranded RNAs originated from two LdATPaseE fragments LdATPaseE1 and LdATPaseE2, the target mRNA levels in the larvae were reduced by 85% and 55%, the larval growth and survival were significantly affected. Furthermore, topical application of fipronil, butane-fipronil, endosulfan and cypermethrin significantly upregulated LdATPaseE expression up to 8.3, 4.2, 2.8 and 6.2-fold 1 day after experiment, and up to 15.8, 3.4, 3.6 and 4.5-fold 2 days after treatment. It seems that depletion of vATPase subunit E is lethal, indicating that targeting vATPases by dsRNA appears a promising means of combating L. decemlineata. Moreover, vATPase subunit E is a pesticide inducible gene and may play a role in pesticide toxicity.
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Affiliation(s)
- Kai-Yun Fu
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
| | - Wen-Chao Guo
- Department of Plant Protection, Xinjiang Academy of Agricultural Sciences, Urumqi 830091, China.
| | - Feng-gong Lü
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
| | - Xin-ping Liu
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
| | - Guo-qing Li
- Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
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Vacuolar H+-ATPase: An Essential Multitasking Enzyme in Physiology and Pathophysiology. ACTA ACUST UNITED AC 2014. [DOI: 10.1155/2014/675430] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Vacuolar H+-ATPases (V-ATPases) are large multisubunit proton pumps that are required for housekeeping acidification of membrane-bound compartments in eukaryotic cells. Mammalian V-ATPases are composed of 13 different subunits. Their housekeeping functions include acidifying endosomes, lysosomes, phagosomes, compartments for uncoupling receptors and ligands, autophagosomes, and elements of the Golgi apparatus. Specialized cells, including osteoclasts, intercalated cells in the kidney and pancreatic beta cells, contain both the housekeeping V-ATPases and an additional subset of V-ATPases, which plays a cell type specific role. The specialized V-ATPases are typically marked by the inclusion of cell type specific isoforms of one or more of the subunits. Three human diseases caused by mutations of isoforms of subunits have been identified. Cancer cells utilize V-ATPases in unusual ways; characterization of V-ATPases may lead to new therapeutic modalities for the treatment of cancer. Two accessory proteins to the V-ATPase have been identified that regulate the proton pump. One is the (pro)renin receptor and data is emerging that indicates that V-ATPase may be intimately linked to renin/angiotensin signaling both systemically and locally. In summary, V-ATPases play vital housekeeping roles in eukaryotic cells. Specialized versions of the pump are required by specific organ systems and are involved in diseases.
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Okamoto-Terry H, Umeki K, Nakanishi-Matsui M, Futai M. Glu-44 in the amino-terminal α-helix of yeast vacuolar ATPase E subunit (Vma4p) has a role for VoV1 assembly. J Biol Chem 2013; 288:36236-43. [PMID: 24196958 DOI: 10.1074/jbc.m113.506741] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The proton (H(+)) pumping vacuolar-type ATPase (V-ATPase) is a rotary enzyme that plays a pivotal role in forming intracellular acidic compartments in eukaryotic cells. In Saccharomyces cerevisiae, the membrane extrinsic catalytic V1 and the transmembrane proton-pumping Vo complexes have been shown to reversibly dissociate upon removal of glucose from the medium. However, the basis of this disassembly is largely unknown. In the earlier study, we have found that the amino-terminal α-helical domain between Lys-33 and Lys-83 of yeast E subunit (Vma4p) in the peripheral stalk of the V1 complex has a role in glucose-dependent VoV1 assembly. Results of alanine-scanning mutagenesis within the domain revealed that the Vma4p Glu-44 is a key residue in VoV1 disassembly. Biochemical analysis on Vma4p Glu-44 to Ala, Asn, Asp, and Gln substitutions indicated that Glu-44 has a role in V-ATPase catalysis. These results suggest that Glu-44 is one of the key functional residues for subunit interaction in the V-ATPase stalk complex that allows both efficient rotation catalysis and assembly.
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Affiliation(s)
- Haruko Okamoto-Terry
- From the Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, Futai Special Laboratory, Yahaba, Iwate 028-3694, Japan
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Salyer SA, Olberding JR, Distler AA, Lederer ED, Clark BJ, Delamere NA, Khundmiri SJ. Vacuolar ATPase driven potassium transport in highly metastatic breast cancer cells. Biochim Biophys Acta Mol Basis Dis 2013; 1832:1734-43. [PMID: 23639630 DOI: 10.1016/j.bbadis.2013.04.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 04/19/2013] [Accepted: 04/22/2013] [Indexed: 10/26/2022]
Abstract
Breast cancer is the second leading cause of death in women and thus has received a great deal of attention by researchers. Recent studies suggested decreased occurrence of cancer in patients treated with cardiac glycosides (CGs) for heart conditions. Because CGs induce their cellular effects via the Na(+), K(+) ATPase (Na-K), we treated four breast cancer cell lines (MCF-7, T47D, MDA-MB453, and MDA-MB231) and a non-cancerous breast ductal epithelial cell line (MCF-10A) with ouabain, a well-characterized CG, and measured cell proliferation by measuring bromodeoxyuridine incorporation. Ouabain (1μM) decreased cell proliferation in all cell lines studied except MDA-MB453 cells. Western blot of Na-K α and β subunits showed α1, α3, and β1 expression in all cell lines except MDA-MB453 cells where Na-K protein and mRNA were absent. Potassium uptake, measured as rubidium ((86)Rb) flux, and intracellular potassium were both significantly higher in MDA-MB453 cells compared to MCF-10A cells. RT-qPCR suggested a 7 fold increase in voltage-gated potassium channel (KCNQ2) expression in MDA-MB453 cells compared to MCF-10A cells. Inhibition of KCNQ2 prevented cell growth and (86)Rb uptake in MDA-MB453 cells but not in MCF-10A cells. All cancer cells had significantly higher vacuolar H-ATPase (V-ATPase) activity than MCF-10A cells. Inhibition of V-ATPase decreased (86)Rb uptake and intracellular potassium in MDA-MB453 cells but not in MCF-10A cells. The findings point to the absence of Na-K, high hERG and KCNQ2 expression, elevated V-ATPase activity and sensitivity to V-ATPase inhibitors in MDA-MB453. We conclude that cancer cells exhibit fundamentally different metabolic pathways for maintenance of intracellular ion homeostasis.
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Affiliation(s)
- Sarah A Salyer
- Department of Medicine, University of Louisville, Louisville, KY, USA
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Parsons LS, Wilkens S. Probing subunit-subunit interactions in the yeast vacuolar ATPase by peptide arrays. PLoS One 2012; 7:e46960. [PMID: 23071676 PMCID: PMC3470569 DOI: 10.1371/journal.pone.0046960] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 09/07/2012] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Vacuolar (H(+))-ATPase (V-ATPase; V(1)V(o)-ATPase) is a large multisubunit enzyme complex found in the endomembrane system of all eukaryotic cells where its proton pumping action serves to acidify subcellular organelles. In the plasma membrane of certain specialized tissues, V-ATPase functions to pump protons from the cytoplasm into the extracellular space. The activity of the V-ATPase is regulated by a reversible dissociation mechanism that involves breaking and re-forming of protein-protein interactions in the V(1)-ATPase - V(o)-proton channel interface. The mechanism responsible for regulated V-ATPase dissociation is poorly understood, largely due to a lack of detailed knowledge of the molecular interactions that are responsible for the structural and functional link between the soluble ATPase and membrane bound proton channel domains. METHODOLOGY/PRINCIPAL FINDINGS To gain insight into where some of the stator subunits of the V-ATPase associate with each other, we have developed peptide arrays from the primary sequences of V-ATPase subunits. By probing the peptide arrays with individually expressed V-ATPase subunits, we have identified several key interactions involving stator subunits E, G, C, H and the N-terminal domain of the membrane bound a subunit. CONCLUSIONS The subunit-peptide interactions identified from the peptide arrays complement low resolution structural models of the eukaryotic vacuolar ATPase obtained from transmission electron microscopy. The subunit-subunit interaction data are discussed in context of our current model of reversible enzyme dissociation.
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Affiliation(s)
- Lee S. Parsons
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, United States of America
| | - Stephan Wilkens
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York, United States of America
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13
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Oot RA, Huang LS, Berry EA, Wilkens S. Crystal structure of the yeast vacuolar ATPase heterotrimeric EGC(head) peripheral stalk complex. Structure 2012; 20:1881-92. [PMID: 23000382 DOI: 10.1016/j.str.2012.08.020] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 08/19/2012] [Accepted: 08/20/2012] [Indexed: 12/17/2022]
Abstract
Vacuolar ATPases (V-ATPases) are multisubunit rotary motor proton pumps that function to acidify subcellular organelles in all eukaryotic organisms. V-ATPase is regulated by a unique mechanism that involves reversible dissociation into V₁-ATPase and V₀ proton channel, a process that involves breaking of protein interactions mediated by subunit C, the cytoplasmic domain of subunit "a" and three "peripheral stalks," each made of a heterodimer of E and G subunits. Here, we present crystal structures of a yeast V-ATPase heterotrimeric complex composed of EG heterodimer and the head domain of subunit C (C(head)). The structures show EG heterodimer folded in a noncanonical coiled coil that is stabilized at its N-terminal ends by binding to C(head). The coiled coil is disrupted by a bulge of partially unfolded secondary structure in subunit G and we speculate that this unique feature in the eukaryotic V-ATPase peripheral stalk may play an important role in enzyme structure and regulation by reversible dissociation.
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Affiliation(s)
- Rebecca A Oot
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210, USA
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Qin A, Cheng TS, Pavlos NJ, Lin Z, Dai KR, Zheng MH. V-ATPases in osteoclasts: structure, function and potential inhibitors of bone resorption. Int J Biochem Cell Biol 2012; 44:1422-35. [PMID: 22652318 DOI: 10.1016/j.biocel.2012.05.014] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Revised: 05/18/2012] [Accepted: 05/18/2012] [Indexed: 01/06/2023]
Abstract
The vacuolar-type H(+)-ATPase (V-ATPase) proton pump is a macromolecular complex composed of at least 14 subunits organized into two functional domains, V(1) and V(0). The complex is located on the ruffled border plasma membrane of bone-resorbing osteoclasts, mediating extracellular acidification for bone demineralization during bone resorption. Genetic studies from mice to man implicate a critical role for V-ATPase subunits in osteoclast-related diseases including osteopetrosis and osteoporosis. Thus, the V-ATPase complex is a potential molecular target for the development of novel anti-resorptive agents useful for the treatment of osteolytic diseases. Here, we review the current structure and function of V-ATPase subunits, emphasizing their exquisite roles in osteoclastic function. In addition, we compare several distinct classes of V-ATPase inhibitors with specific inhibitory effects on osteoclasts. Understanding the structure-function relationship of the osteoclast V-ATPase may lead to the development of osteoclast-specific V-ATPase inhibitors that may serve as alternative therapies for the treatment of osteolytic diseases.
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Affiliation(s)
- A Qin
- Centre for Orthopaedic Research, School of Surgery, The University of Western Australia, Crawley, Australia.
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15
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Rotational catalysis in proton pumping ATPases: from E. coli F-ATPase to mammalian V-ATPase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1711-21. [PMID: 22459334 DOI: 10.1016/j.bbabio.2012.03.015] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2012] [Revised: 03/10/2012] [Accepted: 03/13/2012] [Indexed: 01/28/2023]
Abstract
We focus on the rotational catalysis of Escherichia coli F-ATPase (ATP synthase, F(O)F(1)). Using a probe with low viscous drag, we found stochastic fluctuation of the rotation rates, a flat energy pathway, and contribution of an inhibited state to the overall behavior of the enzyme. Mutational analyses revealed the importance of the interactions among β and γ subunits and the β subunit catalytic domain. We also discuss the V-ATPase, which has different physiological roles from the F-ATPase, but is structurally and mechanistically similar. We review the rotation, diversity of subunits, and the regulatory mechanism of reversible subunit dissociation/assembly of Saccharomyces cerevisiae and mammalian complexes. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012).
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Molina MF, Qu HQ, Rentfro AR, Nair S, Lu Y, Hanis CL, McCormick JB, Fisher-Hoch SP. Decreased expression of ATP6V1H in type 2 diabetes: a pilot report on the diabetes risk study in Mexican Americans. Biochem Biophys Res Commun 2011; 412:728-31. [PMID: 21871445 DOI: 10.1016/j.bbrc.2011.08.041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 08/10/2011] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Previous studies in mice and humans observed down-regulation of the gene expression of ATP6V1H associated with type 2 diabetes. This study identified prospectively changes in ATP6V1H expression before and after overt diabetes. METHODS Expression of ATP6V1H in peripheral blood was compared pre and post development of diabetes in nine individuals. RESULTS Considerable variation of ATP6V1H mRNA levels was observed between different individuals. However, within each individual the decrease in expression of ATP6V1H with the development of diabetes was highly statistically significant. CONCLUSIONS ATP6V1H may represent a critical molecular mechanism involved in the development of type 2 diabetes and its compilations through its important regulatory effect on vacuolar-ATPase activity.
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Affiliation(s)
- Melanie F Molina
- Division of Epidemiology, Human Genetics and Environmental Sciences, Brownsville Regional Campus, The University of Texas School of Public Health, Brownsville, TX, USA
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Srinivasan S, Vyas NK, Baker ML, Quiocho FA. Crystal structure of the cytoplasmic N-terminal domain of subunit I, a homolog of subunit a, of V-ATPase. J Mol Biol 2011; 412:14-21. [PMID: 21787787 DOI: 10.1016/j.jmb.2011.07.014] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Revised: 07/08/2011] [Accepted: 07/12/2011] [Indexed: 11/17/2022]
Abstract
Subunit "a" is associated with the membrane-bound (V(O)) complex of eukaryotic vacuolar H(+)-ATPase acidification machinery. It has also been shown recently to be involved in diverse membrane fusion/secretory functions independent of acidification. Here, we report the crystal structure of the N-terminal cytosolic domain from the Meiothermus ruber subunit "I" homolog of subunit a. The structure is composed of a curved long central α-helix bundle capped on both ends by two lobes with similar α/β architecture. Based on the structure, a reasonable model of its eukaryotic subunit a counterpart was obtained. The crystal structure and model fit well into reconstructions from electron microscopy of prokaryotic and eukaryotic vacuolar H(+)-ATPases, respectively, clarifying their orientations and interactions and revealing features that could enable subunit a to play a role in membrane fusion/secretion.
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Affiliation(s)
- Sankaranarayanan Srinivasan
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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18
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Ahmad A, Khundmiri SJ, Pribble F, Merchant ML, Ameen M, Klein JB, Levi M, Lederer ED. Role of vacuolar ATPase in the trafficking of renal type IIa sodium-phosphate cotransporter. Cell Physiol Biochem 2011; 27:703-14. [PMID: 21691088 DOI: 10.1159/000330079] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Total body phosphate homeostasis is regulated by expression of type IIa sodium phosphate cotransporter (NpT2a) in the apical membrane (BBM) of renal proximal tubule cells. NpT2a expression is regulated by dietary phosphate and PTH but the mechanisms for trafficking of the protein are unknown. Based on 2D gel electrophoresis and mass spectroscopy data that changes in dietary phosphate stimulated changes in BBM expression of vacuolar H(+)-ATPase, we hypothesized that vacuolar H(+)-ATPase plays a significant role in regulation of NpT2a in opossum kidney (OK) cells, a model for renal proximal tubule transport. METHODS Role of vacuolar H(+)-ATPase was studied in opossum kidney (OK) cells by examining the effect of inhibition of vacuolar H(+)-ATPase on Pi uptake and NpT2a expression. RESULTS Pretreatment of OK cells with bafilomycin A(1) and concanamycin A, inhibitors of vacuolar H(+)-ATPases, blocked high phosphate- and PTH-induced degradation of NpT2a, but had no effect on high phosphate or PTH induced inhibition of sodium-dependent phosphate transport. Exposure of the cells to bafilomycin A(1) significantly decreased phosphate transport and apical membrane expression of NpT2a. Treatment with brefeldin A, an inhibitor of Golgi transport, decreased phosphate transport and apical membrane expression of NpT2a while treatment of cells with both brefeldin A and bafilomycin A(1) had no additive effect. CONCLUSION We conclude that vacuolar H(+)-ATPase plays a significant role in exocytosis of NpT2a into the apical membrane and in degradation of NpT2a but has no role in endocytosis.
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Affiliation(s)
- Aamir Ahmad
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
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19
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Abstract
AbstractThe rotary ATPase family of membrane protein complexes may have only three members, but each one plays a fundamental role in biological energy conversion. The F1Fo-ATPase (F-ATPase) couples ATP synthesis to the electrochemical membrane potential in bacteria, mitochondria and chloroplasts, while the vacuolar H+-ATPase (V-ATPase) operates as an ATP-driven proton pump in eukaryotic membranes. In different species of archaea and bacteria, the A1Ao-ATPase (A-ATPase) can function as either an ATP synthase or an ion pump. All three of these multi-subunit complexes are rotary molecular motors, sharing a fundamentally similar mechanism in which rotational movement drives the energy conversion process. By analogy to macroscopic systems, individual subunits can be assigned to rotor, axle or stator functions. Recently, three-dimensional reconstructions from electron microscopy and single particle image processing have led to a significant step forward in understanding of the overall architecture of all three forms of these complexes and have allowed the organisation of subunits within the rotor and stator parts of the motors to be more clearly mapped out. This review describes the emerging consensus regarding the organisation of the rotor and stator components of V-, A- and F-ATPases, examining core similarities that point to a common evolutionary origin, and highlighting key differences. In particular, it discusses how newly revealed variation in the complexity of the inter-domain connections may impact on the mechanics and regulation of these molecular machines.
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20
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Rishikesan S, Thaker YR, Grüber G. NMR solution structure of subunit E (fragment E1–69) of the Saccharomyces cerevisiae V1VO ATPase. J Bioenerg Biomembr 2011; 43:187-93. [DOI: 10.1007/s10863-011-9342-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Accepted: 01/31/2011] [Indexed: 11/29/2022]
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21
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Lange C, Prenninger S, Knuckles P, Taylor V, Levin M, Calegari F. The H(+) vacuolar ATPase maintains neural stem cells in the developing mouse cortex. Stem Cells Dev 2011; 20:843-50. [PMID: 21126173 DOI: 10.1089/scd.2010.0484] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The vacuolar H(+) ATPase (v-ATPase) is crucial for endosome acidification, endocytosis, and trafficking in essentially all eukaryotic cells. Recent studies have shown that inhibition of the v-ATPase also leads to downregulation of important signaling pathways, including Notch and Wnt, which are key regulators of cell differentiation and tissue homeostasis across the animal kingdom. However, the requirement of endosome acidification and endocytosis in the transduction of Notch signaling is still highly debated. Moreover, no study has yet investigated the role of the v-ATPase during mammalian development. Here we show that expression of a dominant-negative subunit of the v-ATPase in neural precursors of the developing mouse cortex depleted neural stem cells by promoting their differentiation and the generation of neurons. Moreover, inhibition of the v-ATPase reduced endogenous Notch signaling and prevented the proliferative effect of a transmembrane, γ-secretase-dependent, active Notch without blocking the effects of its cytoplasmic intracellular domain (NICD). Our data are consistent with recent reports in Drosophila in which the v-ATPase has been suggested to be important for the transduction of Notch signaling. By extending these reports to mammalian embryos, our data may contribute to a better understanding of the role of the v-ATPase, endosome acidification, and endocytosis in signal transduction during neural stem cell differentiation and brain development.
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Affiliation(s)
- Christian Lange
- DFG-Research Center and Cluster of Excellence for Regenerative Therapies, Technische Universität Dresden, Dresden, Germany
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22
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Sihn G, Rousselle A, Vilianovitch L, Burckle C, Bader M. Physiology of the (pro)renin receptor: Wnt of change? Kidney Int 2010; 78:246-56. [DOI: 10.1038/ki.2010.151] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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The NMR solution structure of subunit G (G(61)(-)(101)) of the eukaryotic V1VO ATPase from Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1961-8. [PMID: 20599533 DOI: 10.1016/j.bbamem.2010.06.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 06/14/2010] [Accepted: 06/15/2010] [Indexed: 11/20/2022]
Abstract
Subunit G is an essential stalk subunit of the eukaryotic proton pump V(1)V(O) ATPase. Previously the structure of the N-terminal region, G(1)(-)(59), of the 13kDa subunit G was solved at higher resolution. Here solution NMR was performed to determine the structure of the recombinant C-terminal region (G(61)(-)(101)) of subunit G of the Saccharomyces cerevisiae V(1)V(O) ATPase. The protein forms an extended alpha-helix between residues 64 and 100, whereby the first five- and the last residues of G(61)(-)(101) are flexible. The surface charge distribution of G(61)(-)(101) reveals an amphiphilic character at the C-terminus due to positive and negative charge distribution at one side and a hydrophobic surface on the opposite side of the structure. The hydrophobic surface pattern is mainly formed by alanine residues. The alanine residues 72, 74 and 81 were exchanged by a single cysteine in the entire subunit G. Cysteines at positions 72 and 81 showed disulfide formation. In contrast, no crosslink could be formed for the mutant Ala74Cys. Together with the recently determined NMR solution structure of G(1)(-)(59), the presented solution structure of G(61)(-)(101) enabled us to present a first structural model of the entire subunit G of the S. cerevisiae V(1)V(O) ATPase.
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24
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Jones RPO, Durose LJ, Phillips C, Keen JN, Findlay JBC, Harrison MA. A site-directed cross-linking approach to the characterization of subunit E-subunit G contacts in the vacuolar H+-ATPase stator. Mol Membr Biol 2010; 27:147-59. [DOI: 10.3109/09687681003796441] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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25
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Cruciat CM, Ohkawara B, Acebron SP, Karaulanov E, Reinhard C, Ingelfinger D, Boutros M, Niehrs C. Requirement of prorenin receptor and vacuolar H+-ATPase-mediated acidification for Wnt signaling. Science 2010; 327:459-63. [PMID: 20093472 DOI: 10.1126/science.1179802] [Citation(s) in RCA: 439] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Wnt/beta-catenin signaling is important in stem cell biology, embryonic development, and disease, including cancer. However, the mechanism of Wnt signal transmission, notably how the receptors are activated, remains incompletely understood. We found that the prorenin receptor (PRR) is a component of the Wnt receptor complex. PRR functions in a renin-independent manner as an adaptor between Wnt receptors and the vacuolar H+-adenosine triphosphatase (V-ATPase) complex. Moreover, PRR and V-ATPase were required to mediate Wnt signaling during antero-posterior patterning of Xenopus early central nervous system development. The results reveal an unsuspected role for the prorenin receptor, V-ATPase activity, and acidification during Wnt/beta-catenin signaling.
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Affiliation(s)
- Cristina-Maria Cruciat
- Division of Molecular Embryology, DKFZ-ZMBH Alliance, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
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26
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Dettmer J, Liu TY, Schumacher K. Functional analysis of Arabidopsis V-ATPase subunit VHA-E isoforms. Eur J Cell Biol 2009; 89:152-6. [PMID: 19945769 DOI: 10.1016/j.ejcb.2009.11.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Acidification of endomembrane compartments by the vacuolar H(+)-ATPase (V-ATPase) is an important mechanism to generate microenvironments suitable for various cellular functions. Differential assembly of subunit isoforms provides the potential to flexibly adapt the proton-pumping V-ATPase complex to changing physiological conditions and cell type-specific requirements. In Arabidopsis, the regulatory V-ATPase subunit E (VHA-E) is encoded by three genes with distinct expression patterns. We show here that VHA-E2, which belongs to a clade of pollen-specific VHA-E isoforms present in all higher plants, has a specialized but non-essential function during gametophyte development. Similarly, loss of the epidermis-specific isoform VHA-E3, which we show here to be transcriptionally regulated by the phytohormone jasmonic acid, does not cause obvious phenotypic changes. Furthermore, when expressed ubiquitously, VHA-E3, in contrast to VHA-E2, is able to complement loss of the essential subunit VHA-E1 indicating different degrees of functional specialization among the Arabidopsis VHA-E isoforms.
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Affiliation(s)
- Jan Dettmer
- ZMBP - Plant Physiology, Universität Tübingen, Auf der Morgenstelle 1, 72076 Tübingen, Germany
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27
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Chodaczek G, Bacsi A, Dharajiya N, Sur S, Hazra TK, Boldogh I. Ragweed pollen-mediated IgE-independent release of biogenic amines from mast cells via induction of mitochondrial dysfunction. Mol Immunol 2009; 46:2505-14. [PMID: 19501909 DOI: 10.1016/j.molimm.2009.05.023] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Accepted: 05/18/2009] [Indexed: 11/16/2022]
Abstract
Normal functions of mitochondria are required for physiological dynamics of cells, while their dysfunction contributes to development of various disorders including those of immune system. Here we demonstrate that exposure of mast cells to ragweed pollen extract increases production of H(2)O(2) via mitochondrial respiratory complex III. These mitochondrial ROS (mtROS) enhance secretion of histamine and serotonin from mast cells, but not enzymes such as beta-hexosaminidase, independently from FcvarepsilonRI-generated stimuli. The release of biogenic amines is associated with inhibition of secretory granules' H(+)-ATPase activity, activation of PKC-delta and microtubule-dependent motility, and it is independent from intracellular free Ca(2+) levels. To asses differences from IgE-mediated mast cell degranulation we show that mtROS decrease antigen-triggered beta-hexosaminidase release, while they are synergistic with antigen-induced IL-4 production in sensitized cells. Taken together, these data indicate that mitochondrial dysfunction can act independently from adaptive immunity, as well as augments Th2-type responses. Pharmacological maintenance of physiological mitochondrial function could have clinical benefits in prevention and treatment of allergic diseases.
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Affiliation(s)
- Grzegorz Chodaczek
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, TX 77555, USA
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28
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Diab H, Ohira M, Liu M, Cobb E, Kane PM. Subunit interactions and requirements for inhibition of the yeast V1-ATPase. J Biol Chem 2009; 284:13316-13325. [PMID: 19299516 DOI: 10.1074/jbc.m900475200] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Disassembly of the yeast V-ATPase into cytosolic V(1) and membrane V(0) sectors inactivates MgATPase activity of the V(1)-ATPase. This inactivation requires the V(1) H subunit (Parra, K. J., Keenan, K. L., and Kane, P. M. (2000) J. Biol. Chem. 275, 21761-21767), but its mechanism is not fully understood. The H subunit has two domains. Interactions of each domain with V(1) and V(0) subunits were identified by two-hybrid assay. The B subunit of the V(1) catalytic headgroup interacted with the H subunit N-terminal domain (H-NT), and the C-terminal domain (H-CT) interacted with V(1) subunits B, E (peripheral stalk), and D (central stalk), and the cytosolic N-terminal domain of V(0) subunit Vph1p. V(1)-ATPase complexes from yeast expressing H-NT are partially inhibited, exhibiting 26% the MgATPase activity of complexes with no H subunit. The H-CT domain does not copurify with V(1) when expressed in yeast, but the bacterially expressed and purified H-CT domain inhibits MgATPase activity in V(1) lacking H almost as well as the full-length H subunit. Binding of full-length H subunit to V(1) was more stable than binding of either H-NT or H-CT, suggesting that both domains contribute to binding and inhibition. Intact H and H-CT can bind to the expressed N-terminal domain of Vph1p, but this fragment of Vph1p does not bind to V(1) complexes containing subunit H. We propose that upon disassembly, the H subunit undergoes a conformational change that inhibits V(1)-ATPase activity and precludes V(0) interactions.
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Affiliation(s)
- Heba Diab
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210
| | - Masashi Ohira
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210
| | - Mali Liu
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210
| | - Ester Cobb
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210
| | - Patricia M Kane
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, New York 13210.
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29
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Muench SP, Huss M, Song CF, Phillips C, Wieczorek H, Trinick J, Harrison MA. Cryo-electron Microscopy of the Vacuolar ATPase Motor Reveals its Mechanical and Regulatory Complexity. J Mol Biol 2009; 386:989-99. [DOI: 10.1016/j.jmb.2009.01.014] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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30
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Assembly of subunit d (Vma6p) and G (Vma10p) and the NMR solution structure of subunit G (G(1-59)) of the Saccharomyces cerevisiae V(1)V(O) ATPase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:242-51. [PMID: 19344662 DOI: 10.1016/j.bbabio.2009.01.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 01/12/2009] [Accepted: 01/13/2009] [Indexed: 11/21/2022]
Abstract
Understanding the structural traits of subunit G is essential, as it is needed for V(1)V(O) assembly and function. Here solution NMR of the recombinant N- (G(1-59)) and C-terminal segment (G(61-114)) of subunit G, has been performed in the absence and presence of subunit d of the yeast V-ATPase. The data show that G does bind to subunit d via its N-terminal part, G(1-59) only. The residues of G(1-59) involved in d binding are Gly7 to Lys34. The structure of G(1-59) has been solved, revealing an alpha-helix between residues 10 and 56, whereby the first nine- and the last three residues of G(1-59) are flexible. The surface charge distribution of G(1-59) reveals an amphiphilic character at the N-terminus due to positive and negative charge distribution at one side and a hydrophobic surface on the opposite side of the structure. The C-terminus exhibits a strip of negative residues. The data imply that G(1-59)-d assembly is accomplished by hydrophobic interactions and salt-bridges of the polar residues. Based on the recently determined NMR structure of segment E(18-38) of subunit E of yeast V-ATPase and the presently solved structure of G(1-59), both proteins have been docked and binding epitopes have been analyzed.
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31
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Zhang Z, Zheng Y, Mazon H, Milgrom E, Kitagawa N, Kish-Trier E, Heck AJR, Kane PM, Wilkens S. Structure of the yeast vacuolar ATPase. J Biol Chem 2008; 283:35983-95. [PMID: 18955482 PMCID: PMC2602884 DOI: 10.1074/jbc.m805345200] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Revised: 10/15/2008] [Indexed: 01/01/2023] Open
Abstract
The subunit architecture of the yeast vacuolar ATPase (V-ATPase) was analyzed by single particle transmission electron microscopy and electrospray ionization (ESI) tandem mass spectrometry. A three-dimensional model of the intact V-ATPase was calculated from two-dimensional projections of the complex at a resolution of 25 angstroms. Images of yeast V-ATPase decorated with monoclonal antibodies against subunits A, E, and G position subunit A within the pseudo-hexagonal arrangement in the V1, the N terminus of subunit G in the V1-V0 interface, and the C terminus of subunit E at the top of the V1 domain. ESI tandem mass spectrometry of yeast V1-ATPase showed that subunits E and G are most easily lost in collision-induced dissociation, consistent with a peripheral location of the subunits. An atomic model of the yeast V-ATPase was generated by fitting of the available x-ray crystal structures into the electron microscopy-derived electron density map. The resulting atomic model of the yeast vacuolar ATPase serves as a framework to help understand the role the peripheral stalk subunits are playing in the regulation of the ATP hydrolysis driven proton pumping activity of the vacuolar ATPase.
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Affiliation(s)
- Zhenyu Zhang
- Department of Biochemistry, University of California, Riverside, California 92521, USA
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32
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Diepholz M, Venzke D, Prinz S, Batisse C, Flörchinger B, Rössle M, Svergun DI, Böttcher B, Féthière J. A Different Conformation for EGC Stator Subcomplex in Solution and in the Assembled Yeast V-ATPase: Possible Implications for Regulatory Disassembly. Structure 2008; 16:1789-98. [DOI: 10.1016/j.str.2008.09.010] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Revised: 09/17/2008] [Accepted: 09/18/2008] [Indexed: 11/29/2022]
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33
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Jefferies KC, Cipriano DJ, Forgac M. Function, structure and regulation of the vacuolar (H+)-ATPases. Arch Biochem Biophys 2008; 476:33-42. [PMID: 18406336 PMCID: PMC2543942 DOI: 10.1016/j.abb.2008.03.025] [Citation(s) in RCA: 179] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Revised: 03/05/2008] [Accepted: 03/07/2008] [Indexed: 02/07/2023]
Abstract
The vacuolar ATPases (or V-ATPases) are ATP-driven proton pumps that function to both acidify intracellular compartments and to transport protons across the plasma membrane. Intracellular V-ATPases function in such normal cellular processes as receptor-mediated endocytosis, intracellular membrane traffic, prohormone processing, protein degradation and neurotransmitter uptake, as well as in disease processes, including infection by influenza and other viruses and killing of cells by anthrax and diphtheria toxin. Plasma membrane V-ATPases are important in such physiological processes as urinary acidification, bone resorption and sperm maturation as well as in human diseases, including osteopetrosis, renal tubular acidosis and tumor metastasis. V-ATPases are large multi-subunit complexes composed of a peripheral domain (V(1)) responsible for hydrolysis of ATP and an integral domain (V(0)) that carries out proton transport. Proton transport is coupled to ATP hydrolysis by a rotary mechanism. V-ATPase activity is regulated in vivo using a number of mechanisms, including reversible dissociation of the V(1) and V(0) domains, changes in coupling efficiency of proton transport and ATP hydrolysis and changes in pump density through reversible fusion of V-ATPase containing vesicles. V-ATPases are emerging as potential drug targets in treating a number of human diseases including osteoporosis and cancer.
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Affiliation(s)
| | | | - Michael Forgac
- Department of Physiology, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111
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Hayashi K, Sun-Wada GH, Wada Y, Nakanishi-Matsui M, Futai M. Defective assembly of a hybrid vacuolar H(+)-ATPase containing the mouse testis-specific E1 isoform and yeast subunits. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:1370-7. [PMID: 18662668 DOI: 10.1016/j.bbabio.2008.06.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Revised: 06/26/2008] [Accepted: 06/30/2008] [Indexed: 01/10/2023]
Abstract
Mammalian vacuolar-type proton pumping ATPases (V-ATPases) are diverse multi-subunit proton pumps. They are formed from membrane V(o) and catalytic V(1) sectors, whose subunits have cell-specific or ubiquitous isoforms. Biochemical study of a unique V-ATPase is difficult because ones with different isoforms are present in the same cell. However, the properties of mouse isoforms can be studied using hybrid V-ATPases formed from the isoforms and other yeast subunits. As shown previously, mouse subunit E isoform E1 (testis-specific) or E2 (ubiquitous) can form active V-ATPases with other subunits of yeast, but E1/yeast hybrid V-ATPase is defective in proton transport at 37 degrees C (Sun-Wada, G.-H., Imai-Senga, Y., Yamamoto, A., Murata, Y., Hirata, T., Wada, Y., and Futai, M., 2002, J. Biol. Chem. 277, 18098-18105). In this study, we have analyzed the properties of E1/yeast hybrid V-ATPase to understand the role of the E subunit. The proton transport by the defective hybrid ATPase was reversibly recovered when incubation temperature of vacuoles or cells was shifted to 30 degrees C. Corresponding to the reversible defect of the hybrid V-ATPase, the V(o) subunit a epitope was exposed to the corresponding antibody at 37 degrees C, but became inaccessible at 30 degrees C. However, the V(1) sector was still associated with V(o) at 37 degrees C, as shown immunochemically. The control yeast V-ATPase was active at 37 degrees C, and its epitope was not accessible to the antibody. Glucose depletion, known to dissociate V(1) from V(o) in yeast, had only a slight effect on the hybrid at acidic pH. The domain between Lys26 and Val83 of E1, which contains eight residues not conserved between E1 and E2, was responsible for the unique properties of the hybrid. These results suggest that subunit E, especially its amino-terminal domain, plays a pertinent role in the assembly of V-ATPase subunits in vacuolar membranes.
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Affiliation(s)
- Kazuhiro Hayashi
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, Iwate, Japan
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35
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Neira Oviedo M, Vanekeris L, Corena-McLeod MDP, Linser PJ. A microarray-based analysis of transcriptional compartmentalization in the alimentary canal of Anopheles gambiae (Diptera: Culicidae) larvae. INSECT MOLECULAR BIOLOGY 2008; 17:61-72. [PMID: 18237285 DOI: 10.1111/j.1365-2583.2008.00779.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The alimentary canal of the larval mosquito displays a considerable degree of physiological compartmentalization among its different anatomical sub-divisions (gastric caeca, anterior midgut, posterior midgut and hindgut). We performed a comparative microarray analysis in order to identify transcripts which are particularly enriched in each gut section. Based on the available annotation of the selected transcripts, we suggest that the metabolism and absorption of proteins and carbohydrates takes place mainly in the gastric caeca and posterior midgut, whereas the anterior midgut specializes in the metabolism and absorption of lipids. Transcripts encoding antimicrobial peptides were found to be enriched in the gastric caeca, and a high enrichment of transcripts associated with enzymes involved in xenobiotic detoxification was found in the anterior midgut. Furthermore, our data support the notion that the region encompassing the hindgut and Malpighian tubes plays important roles in avoiding the excretion of nutrients, as well as in xenobiotic detoxification.
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Affiliation(s)
- M Neira Oviedo
- The Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL 32080, USA
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36
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Jefferies KC, Forgac M. Subunit H of the vacuolar (H+) ATPase inhibits ATP hydrolysis by the free V1 domain by interaction with the rotary subunit F. J Biol Chem 2007; 283:4512-9. [PMID: 18156183 DOI: 10.1074/jbc.m707144200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The vacuolar (H+) ATPases (V-ATPases) are large, multimeric proton pumps that, like the related family of F1F0 ATP synthases, employ a rotary mechanism. ATP hydrolysis by the peripheral V1 domain drives rotation of a rotary complex (the rotor) relative to the stationary part of the enzyme (the stator), leading to proton translocation through the integral V0 domain. One mechanism of regulating V-ATPase activity in vivo involves reversible dissociation of the V1 and V0 domains. Unlike the corresponding domains in F1F0, the dissociated V1 domain does not hydrolyze ATP, and the free V0 domain does not passively conduct protons. These properties are important to avoid generation of an uncoupled ATPase activity or an unregulated proton conductance upon dissociation of the complex in vivo. Previous results (Parra, K. J., Keenan, K. L., and Kane, P. M. (2000) J. Biol. Chem. 275, 21761-21767) showed that subunit H (part of the stator) inhibits ATP hydrolysis by free V1. To test the hypothesis that subunit H accomplishes this by bridging rotor and stator in free V1, cysteine-mediated cross-linking studies were performed. Unique cysteine residues were introduced over the surface of subunit H from yeast by site-directed mutagenesis and used as the site of attachment of the photo-activated cross-linking reagent maleimido benzophenone. After UV-activated cross-linking, cross-linked products were identified by Western blot using subunit-specific antibodies. The results indicate that the subunit H mutant S381C shows cross-linking between subunit H and subunit F (a rotor subunit) in the free V1 domain but not in the intact V1V0 complex. These results indicate that subunits H and F are proximal in free V1, supporting the hypothesis that subunit H inhibits free V1 by bridging the rotary and stator domains.
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Affiliation(s)
- Kevin C Jefferies
- Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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37
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Kitagawa N, Mazon H, Heck AJR, Wilkens S. Stoichiometry of the peripheral stalk subunits E and G of yeast V1-ATPase determined by mass spectrometry. J Biol Chem 2007; 283:3329-3337. [PMID: 18055462 DOI: 10.1074/jbc.m707924200] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The stoichiometry of yeast V(1)-ATPase peripheral stalk subunits E and G was determined by two independent approaches using mass spectrometry (MS). First, the subunit ratio was inferred from measuring the molecular mass of the intact V(1)-ATPase complex and each of the individual protein components, using native electrospray ionization-MS. The major observed intact complex had a mass of 593,600 Da, with minor components displaying masses of 553,550 and 428,300 Da, respectively. Second, defined amounts of V(1)-ATPase purified from yeast grown on (14)N-containing medium were titrated with defined amounts of (15)N-labeled E and G subunits as internal standards. Following protease digestion of subunit bands, (14)N- and (15)N-containing peptide pairs were used for quantification of subunit stoichiometry using matrix-assisted laser desorption/ionization-time of flight MS. Results from both approaches are in excellent agreement and reveal that the subunit composition of yeast V(1)-ATPase is A(3)B(3)DE(3)FG(3)H.
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Affiliation(s)
- Norton Kitagawa
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, New York 13210; Department of Cell, Molecular and Developmental Biology, University of California, Riverside, Riverside, California 92521
| | - Hortense Mazon
- Department of Biomolecular Mass Spectrometry, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CA Utrecht, The Netherlands
| | - Albert J R Heck
- Department of Biomolecular Mass Spectrometry, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CA Utrecht, The Netherlands
| | - Stephan Wilkens
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, New York 13210.
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Abstract
The acidity of intracellular compartments and the extracellular environment is crucial to various cellular processes, including membrane trafficking, protein degradation, bone resorption and sperm maturation. At the heart of regulating acidity are the vacuolar (V-)ATPases--large, multisubunit complexes that function as ATP-driven proton pumps. Their activity is controlled by regulating the assembly of the V-ATPase complex or by the dynamic regulation of V-ATPase expression on membrane surfaces. The V-ATPases have been implicated in a number of diseases and, coupled with their complex isoform composition, represent attractive and potentially highly specific drug targets.
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Affiliation(s)
- Michael Forgac
- Department of Physiology, Tufts University School of Medicine, 136 Harrison Ave., Boston, Massachusetts 02111, USA.
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Lu M, Ammar D, Ives H, Albrecht F, Gluck SL. Physical interaction between aldolase and vacuolar H+-ATPase is essential for the assembly and activity of the proton pump. J Biol Chem 2007; 282:24495-503. [PMID: 17576770 DOI: 10.1074/jbc.m702598200] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vacuolar proton-translocating ATPases (V-ATPases) are a family of highly conserved proton pumps that couple hydrolysis of cytosolic ATP to proton transport out of the cytosol. Although V-ATPases are involved in a number of cellular processes, how the proton pumps are regulated under physiological conditions is not well understood. We have reported that the glycolytic enzyme aldolase mediates V-ATPase assembly and activity by physical association with the proton pump (Lu, M., Holliday, L. S., Zhang, L., Dunn, W. A., and Gluck, S. L. (2001) J. Biol. Chem. 276, 30407-30413 and Lu, M., Sautin, Y., Holliday, L. S., and Gluck, S. L. (2004) J. Biol. Chem. 279, 8732-8739). In this study, we generate aldolase mutants that lack binding to the B subunit of V-ATPase but retain normal catalytic activities. Functional analysis of the aldolase mutants shows that disruption of binding between aldolase and the B subunit of V-ATPase results in disassembly and malfunction of V-ATPase. In contrast, aldolase enzymatic activity is not required for V-ATPase assembly. Taken together, these findings strongly suggest an important role for physical association between aldolase and V-ATPase in the regulation of the proton pump.
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Affiliation(s)
- Ming Lu
- Department of Medicine, University of California School of Medicine, San Francisco, California 94143-0532, USA.
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40
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Adams DS, Masi A, Levin M. H+ pump-dependent changes in membrane voltage are an early mechanism necessary and sufficient to induce Xenopus tail regeneration. Development 2007; 134:1323-35. [PMID: 17329365 DOI: 10.1242/dev.02812] [Citation(s) in RCA: 202] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In many systems, ion flows and long-term endogenous voltage gradients regulate patterning events, but molecular details remain mysterious. To establish a mechanistic link between biophysical events and regeneration, we investigated the role of ion transport during Xenopus tail regeneration. We show that activity of the V-ATPase H(+) pump is required for regeneration but not wound healing or tail development. The V-ATPase is specifically upregulated in existing wound cells by 6 hours post-amputation. Pharmacological or molecular genetic loss of V-ATPase function and the consequent strong depolarization abrogates regeneration without inducing apoptosis. Uncut tails are normally mostly polarized, with discrete populations of depolarized cells throughout. After amputation, the normal regeneration bud is depolarized, but by 24 hours post-amputation becomes rapidly repolarized by the activity of the V-ATPase, and an island of depolarized cells appears just anterior to the regeneration bud. Tail buds in a non-regenerative ;refractory' state instead remain highly depolarized relative to uncut or regenerating tails. Depolarization caused by V-ATPase loss-of-function results in a drastic reduction of cell proliferation in the bud, a profound mispatterning of neural components, and a failure to regenerate. Crucially, induction of H(+) flux is sufficient to rescue axonal patterning and tail outgrowth in otherwise non-regenerative conditions. These data provide the first detailed mechanistic synthesis of bioelectrical, molecular and cell-biological events underlying the regeneration of a complex vertebrate structure that includes spinal cord, and suggest a model of the biophysical and molecular steps underlying tail regeneration. Control of H(+) flows represents a very important new modality that, together with traditional biochemical approaches, may eventually allow augmentation of regeneration for therapeutic applications.
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Affiliation(s)
- Dany S Adams
- Center for Regenerative and Developmental Biology, Forsyth Institute, and Developmental Biology Department, Harvard School of Dental Medicine, 140 The Fenway, Boston, MA 02115, USA
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41
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Lokanath NK, Matsuura Y, Kuroishi C, Takahashi N, Kunishima N. Dimeric Core Structure of Modular Stator Subunit E of Archaeal H+-ATPase. J Mol Biol 2007; 366:933-44. [PMID: 17189637 DOI: 10.1016/j.jmb.2006.11.088] [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: 10/11/2006] [Revised: 11/29/2006] [Accepted: 11/30/2006] [Indexed: 10/23/2022]
Abstract
Archaeal H(+)-ATPase (A-ATPase) is composed of an A(1) region that hydrolyzes ATP and an integral membrane part A(0) that conducts protons. Subunit E is a component of peripheral stator(s) that physically links A(1) and A(0) parts of the A-ATPase. Here we report the first crystal structure of subunit E of A-ATPase from Pyrococcus horikoshii OT3 at 1.85 A resolution. The protomer structure of subunit E represents a novel fold. The quaternary structure of subunit E is a homodimer, which may constitute the core part of the stator. To investigate the relationship with other stator subunit H, the complex of subunits EH was prepared and characterized using electrophoresis, mass spectrometry, N-terminal sequencing and circular dichroism spectroscopy, which revealed the polymeric and highly helical nature of the EH complex with equimolar stoichiometry of both the subunits. On the basis of the modular architecture of stator subunits, it is suggested that both cytoplasm and membrane sides of the EH complex may interact with other subunits to link A(1) and A(0) parts.
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Affiliation(s)
- Neratur K Lokanath
- Advanced Protein Crystallography Research Group, RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo-Gun, Hyogo, Japan
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42
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Abstract
Bioenergetics and physiology of primary pumps have been revitalized by new insights into the mechanism of energizing biomembranes. Structural information is becoming available, and the three-dimensional structure of F-ATPase is being resolved. The growing understanding of the fundamental mechanism of energy coupling may revolutionize our view of biological processes. The F- and V-ATPases (vacuolar-type ATPase) exhibit a common mechanical design in which nucleotide-binding on the catalytic sector, through a cycle of conformation changes, drives the transmembrane passage of protons by turning a membrane-embedded rotor. This motor can run in forward or reverse directions, hydrolyzing ATP as it pumps protons uphill or creating ATP as protons flow downhill. In contrast to F-ATPases, whose primary function in eukaryotic cells is to form ATP at the expense of the proton-motive force (pmf), V-ATPases function exclusively as an ATP-dependent proton pump. The pmf generated by V-ATPases in organelles and membranes of eukaryotic cells is utilized as a driving force for numerous secondary transport processes. V- and F-ATPases have similar structure and mechanism of action, and several of their subunits evolved from common ancestors. Electron microscopy studies of V-ATPase revealed its general structure at low resolution. Recently, several structures of V-ATPase subunits, solved by X-ray crystallography with atomic resolution, were published. This, together with electron microscopy low-resolution maps of the whole complex, and biochemistry cross-linking experiments, allows construction of a structural model for a part of the complex that may be used as a working hypothesis for future research.
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Affiliation(s)
- Omri Drory
- Department of Biochemistry, The George S. Wise Faculty of Life Sciences, The Daniella Rich Institute for Structural Biology, Tel Aviv University, Tel Aviv, Israel
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43
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Ohira M, Smardon AM, Charsky CMH, Liu J, Tarsio M, Kane PM. The E and G Subunits of the Yeast V-ATPase Interact Tightly and Are Both Present at More Than One Copy per V1 Complex. J Biol Chem 2006; 281:22752-60. [PMID: 16774922 DOI: 10.1074/jbc.m601441200] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The E and G subunits of the yeast V-ATPase are believed to be part of the peripheral or stator stalk(s) responsible for physically and functionally linking the peripheral V1 sector, responsible for ATP hydrolysis, to the membrane V0 sector, containing the proton pore. The E and G subunits interact tightly and specifically, both on a far Western blot of yeast vacuolar proteins and in the yeast two-hybrid assay. Amino acids 13-79 of the E subunit are critical for the E-G two-hybrid interaction. Different tagged versions of the G subunit were expressed in a diploid cell, and affinity purification of cytosolic V1 sectors via a FLAG-tagged G subunit resulted in copurification of a Myc-tagged G subunit, implying more than one G subunit was present in each V1 complex. Similarly, hemagglutinin-tagged E subunit was able to affinity-purify V1 sectors containing an untagged version of the E subunit from heterozygous diploid cells, suggesting that more than one E subunit is present. Overexpression of the subunit G results in a destabilization of subunit E similar to that seen in the complete absence of subunit G (Tomashek, J. J., Graham, L. A., Hutchins, M. U., Stevens, T. H., and Klionsky, D. J. (1997) J. Biol. Chem. 272, 26787-26793). These results are consistent with recent models showing at least two peripheral stalks connecting the V1 and V0 sectors of the V-ATPase and would allow both stalks to be based on an EG dimer.
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Affiliation(s)
- Masashi Ohira
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, New York 13210, USA
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44
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Ochotny N, Van Vliet A, Chan N, Yao Y, Morel M, Kartner N, von Schroeder HP, Heersche JNM, Manolson MF. Effects of human a3 and a4 mutations that result in osteopetrosis and distal renal tubular acidosis on yeast V-ATPase expression and activity. J Biol Chem 2006; 281:26102-11. [PMID: 16840787 DOI: 10.1074/jbc.m601118200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
V-ATPases are multimeric proton pumps. The 100-kDa "a" subunit is encoded by four isoforms (a1-a4) in mammals and two (Vph1p and Stv1p) in yeast. a3 is enriched in osteoclasts and is essential for bone resorption, whereas a4 is expressed in the distal nephron and acidifies urine. Mutations in human a3 and a4 result in osteopetrosis and distal renal tubular acidosis, respectively. Human a3 (G405R and R444L) and a4 (P524L and G820R) mutations were recreated in the yeast ortholog Vph1p, a3 (G424R and R462L), and a4 (W520L and G812R). Mutations in a3 resulted in wild type vacuolar acidification and growth on media containing 4 mM ZnCl2, 200 mM CaCl2, or buffered to pH 7.5 with V-ATPase hydrolytic and pumping activity decreased by 30-35%. Immunoblots confirmed wild type levels for V-ATPase a, A, and B subunits on vacuolar membranes. a4 G812R resulted in defective growth on selective media with V-ATPase hydrolytic and pumping activity decreased by 83-85% yet with wild type levels of a, A, and B subunits on vacuolar membranes. The a4 W520L mutation had defective growth on selective media with no detectable V-ATPase activity and reduced expression of a, A, and B subunits. The a4 W520L mutation phenotypes were dominant negative, as overexpression of wild type yeast a isoforms, Vph1p, or Stv1p, did not restore growth. However, deletion of endoplasmic reticulum assembly factors (Vma12p, Vma21p, and Vma22p) partially restored a and B expression. That a4 W520L affects both Vo and V1 subunits is a unique phenotype for any V-ATPase subunit mutation and supports the concerted pathway for V-ATPase assembly in vivo.
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Affiliation(s)
- Noelle Ochotny
- Department of Pharmacology, University of Toronto, Toronto, Ontario M5G 1G6, Canada
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45
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Adams DS, Robinson KR, Fukumoto T, Yuan S, Albertson RC, Yelick P, Kuo L, McSweeney M, Levin M. Early, H+-V-ATPase-dependent proton flux is necessary for consistent left-right patterning of non-mammalian vertebrates. Development 2006; 133:1657-71. [PMID: 16554361 PMCID: PMC3136117 DOI: 10.1242/dev.02341] [Citation(s) in RCA: 210] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Biased left-right asymmetry is a fascinating and medically important phenomenon. We provide molecular genetic and physiological characterization of a novel, conserved, early, biophysical event that is crucial for correct asymmetry: H+ flux. A pharmacological screen implicated the H+-pump H+-V-ATPase in Xenopus asymmetry, where it acts upstream of early asymmetric markers. Immunohistochemistry revealed an actin-dependent asymmetry of H+-V-ATPase subunits during the first three cleavages. H+-flux across plasma membranes is also asymmetric at the four- and eight-cell stages, and this asymmetry requires H+-V-ATPase activity. Abolishing the asymmetry in H+ flux, using a dominant-negative subunit of the H+-V-ATPase or an ectopic H+ pump, randomized embryonic situs without causing any other defects. To understand the mechanism of action of H+-V-ATPase, we isolated its two physiological functions, cytoplasmic pH and membrane voltage (Vmem) regulation. Varying either pH or Vmem, independently of direct manipulation of H+-V-ATPase, caused disruptions of normal asymmetry, suggesting roles for both functions. V-ATPase inhibition also abolished the normal early localization of serotonin, functionally linking these two early asymmetry pathways. The involvement of H+-V-ATPase in asymmetry is conserved to chick and zebrafish. Inhibition of the H+-V-ATPase induces heterotaxia in both species; in chick, H+-V-ATPase activity is upstream of Shh; in fish, it is upstream of Kupffer's vesicle and Spaw expression. Our data implicate H+-V-ATPase activity in patterning the LR axis of vertebrates and reveal mechanisms upstream and downstream of its activity. We propose a pH- and Vmem-dependent model of the early physiology of LR patterning.
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Affiliation(s)
- Dany S. Adams
- The Forsyth Center for Regenerative and Developmental Biology, and Department of Developmental Biology, Harvard School of Dental Medicine, 140 The Fenway, Boston, MA 02115, USA
| | - Kenneth R. Robinson
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47906, USA
| | - Takahiro Fukumoto
- Department of Cytokine Biology, The Forsyth Institute, 140 The Fenway, Boston, MA 02115, USA
| | - Shipeng Yuan
- Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - R. Craig Albertson
- Department of Cytokine Biology, The Forsyth Institute, 140 The Fenway, Boston, MA 02115, USA
| | - Pamela Yelick
- Department of Cytokine Biology, The Forsyth Institute, 140 The Fenway, Boston, MA 02115, USA
| | - Lindsay Kuo
- Department of Cytokine Biology, The Forsyth Institute, 140 The Fenway, Boston, MA 02115, USA
| | - Megan McSweeney
- Department of Cytokine Biology, The Forsyth Institute, 140 The Fenway, Boston, MA 02115, USA
| | - Michael Levin
- The Forsyth Center for Regenerative and Developmental Biology, and Department of Developmental Biology, Harvard School of Dental Medicine, 140 The Fenway, Boston, MA 02115, USA
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46
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Seidel T, Golldack D, Dietz KJ. Mapping of C-termini of V-ATPase subunits by in vivo-FRET measurements. FEBS Lett 2005; 579:4374-82. [PMID: 16061227 DOI: 10.1016/j.febslet.2005.06.077] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2005] [Revised: 06/27/2005] [Accepted: 06/28/2005] [Indexed: 11/22/2022]
Abstract
The plant V-ATPase is a protein complex of 13 different VHA-subunits and functions as ATP driven motor that electrogenically translocates H+ into endomembrane compartments. The central rotor extends into the hexameric head that is fixed by peripheral stators to an eccentric membrane domain. The localization and orientation of VHA-subunits of the head and peripheral stalk region were investigated by in vivo fluorescence resonance energy transfer (FRET). To this end, VHA-E, VHA-G, VHA-H of the peripheral stalks as well as subunits VHA-A and VHA-B were C-terminally fused to cyan (CFP) and yellow fluorescent protein (YFP). Protoplasts transfected with FRET-pairs of CFP-donor and YFP-acceptor fluorophores fused to VHA-subunits were analysed for FRET by laser scanning microscopy. The result of the C-termini mapping allows to refine the arrangement and interaction of the subunits within the V-ATPase complex in vivo. Furthermore, expression of fused VHA-E and VHA-H stimulated acidification of protoplast vacuoles, while other constructs had no major effect on vacuolar pH tentatively indicating a regulatory role of these subunits in plants.
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Affiliation(s)
- Thorsten Seidel
- Biochemistry and Physiology of Plants, W5, University of Bielefeld, Universitaetsstrasse 25, D-33501 Bielefeld, Germany
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47
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Venzke D, Domgall I, Köcher T, Féthière J, Fischer S, Böttcher B. Elucidation of the Stator Organization in the V-ATPase of Neurospora crassa. J Mol Biol 2005; 349:659-69. [PMID: 15890365 DOI: 10.1016/j.jmb.2005.04.033] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2005] [Revised: 04/13/2005] [Accepted: 04/15/2005] [Indexed: 11/27/2022]
Abstract
V-ATPases are membrane protein complexes that pump protons in the lumen of various subcellular compartments at the expense of ATP. Proton pumping is done by a rotary mechanism that requires a static connection between the membrane pumping domain (V(0)) and the extrinsic catalytic head (V(1)). This static connection is composed of several known subunits of the V-ATPase, but their location and topological relationships are still a matter of controversy. Here, we propose a model for the V-ATPase of Neurospora crassa on the basis of single-particle analysis by electron microscopy. Comparison of the resulting map to that of the A-ATPase from Thermus thermophilus allows the positioning of two subunits in the static connecting region that are unique to eukaryotic V-ATPases (C and H). These two subunits seem to be located on opposite sides of a semicircular arrangement of the peripheral connecting elements, suggesting a role in stabilizing the stator in V-ATPases.
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Affiliation(s)
- David Venzke
- EMBL-Heidelberg Meyerhofstrasse 1, 69117 Heidelberg, Germany
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48
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Wang HL, Zhu ZM, Yerle M, Wu X, Wang H, Yang SL, Li K. Full-length coding sequences and mapping of porcine ATP6VOE and ATP5G1 genes. Cytogenet Genome Res 2005; 109:533. [PMID: 15906478 DOI: 10.1159/000084223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- H L Wang
- Department of Gene and Cell Engineering, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, PR China
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49
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A structural model of the vacuolar ATPase from transmission electron microscopy. Micron 2005; 36:109-26. [PMID: 15629643 DOI: 10.1016/j.micron.2004.10.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2004] [Accepted: 10/11/2004] [Indexed: 11/19/2022]
Abstract
Vacuolar ATPases (V-ATPases) are large, membrane bound, multisubunit protein complexes which function as ATP hydrolysis driven proton pumps. V-ATPases and related enzymes are found in the endomembrane system of eukaryotic organsims, the plasma membrane of specialized cells in higher eukaryotes, and the plasma membrane of prokaryotes. The proton pumping action of the vacuolar ATPase is involved in a variety of vital intra- and inter-cellular processes such as receptor mediated endocytosis, protein trafficking, active transport of metabolites, homeostasis and neurotransmitter release. This review summarizes recent progress in the structure determination of the vacuolar ATPase focusing on studies by transmission electron microscopy. A model of the subunit architecture of the vacuolar ATPase is presented which is based on the electron microscopic images and the available information from genetic, biochemical and biophysical experiments.
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Owegi MA, Carenbauer AL, Wick NM, Brown JF, Terhune KL, Bilbo SA, Weaver RS, Shircliff R, Newcomb N, Parra-Belky KJ. Mutational analysis of the stator subunit E of the yeast V-ATPase. J Biol Chem 2005; 280:18393-402. [PMID: 15718227 DOI: 10.1074/jbc.m412567200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Subunit E is a component of the peripheral stalk(s) that couples membrane and peripheral subunits of the V-ATPase complex. In order to elucidate the function of subunit E, site-directed mutations were performed at the amino terminus and carboxyl terminus. Except for S78A and D233A/T202A, which exhibited V(1)V(o) assembly defects, the function of subunit E was resistant to mutations. Most mutations complemented the growth phenotype of vma4Delta mutants, including T6A and D233A, which only had 25% of the wild-type ATPase activity. Residues Ser-78 and Thr-202 were essential for V(1)V(o) assembly and function. The mutation S78A destabilized subunit E and prevented assembly of V(1) subunits at the membranes. Mutant T202A membranes exhibited 2-fold increased V(max) and about 2-fold less of V(1)V(o) assembly; the mutation increased the specific activity of V(1)V(o) by enhancing the k(cat) of the enzyme 4-fold. Reduced levels of V(1)V(o) and V(o) complexes at T202A membranes suggest that the balance between V(1)V(o) and V(o) was not perturbed; instead, cells adjusted the amount of assembled V-ATPase complexes in order to compensate for the enhanced activity. These results indicated communication between subunit E and the catalytic sites at the A(3)B(3) hexamer and suggest potential regulatory roles for the carboxyl end of subunit E. At the carboxyl end, alanine substitution of Asp-233 significantly reduced ATP hydrolysis, although the truncation 229-233Delta and the point mutation K230A did not affect assembly and activity. The implication of these results for the topology and functions of subunit E within the V-ATPase complex are discussed.
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Affiliation(s)
- Margaret A Owegi
- Department of Chemistry, Ball State University, Muncie, Indiana 47306, USA
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