1
|
Guo Y, Zhang Y, Yan R, Huang B, Ye F, Wu L, Chi X, Shi Y, Zhou Q. Cryo-EM structures of recombinant human sodium-potassium pump determined in three different states. Nat Commun 2022; 13:3957. [PMID: 35803952 PMCID: PMC9270386 DOI: 10.1038/s41467-022-31602-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 06/24/2022] [Indexed: 11/09/2022] Open
Abstract
Sodium-Potassium Pump (Na+/K+-ATPase, NKA) is an ion pump that generates an electrochemical gradient of sodium and potassium ions across the plasma membrane by hydrolyzing ATP. During each Post-Albers cycle, NKA exchanges three cytoplasmic sodium ions for two extracellular potassium ions through alternating changes between the E1 and E2 states. Hitherto, several steps remained unknown during the complete working cycle of NKA. Here, we report cryo-electron microscopy (cryo-EM) structures of recombinant human NKA (hNKA) in three distinct states at 2.7–3.2 Å resolution, representing the E1·3Na and E1·3Na·ATP states with cytosolic gates open and the basic E2·[2K] state, respectively. This work provides the insights into the cytoplasmic Na+ entrance pathway and the mechanism of cytoplasmic gate closure coupled with ATP hydrolysis, filling crucial gaps in the structural elucidation of the Post-Albers cycle of NKA. Sodium-Potassium Pump (Na+/K+-ATPase, NKA) generates an electrochemical gradient of sodium and potassium ions across the plasma membrane by hydrolyzing ATP. Here, the authors report structures of human NKA providing insight into the cytoplasmic Na+ entrance and the cytoplasmic gate closure coupled to ATP hydrolysis.
Collapse
Affiliation(s)
- Yingying Guo
- Westlake Laboratory of Life Sciences and Biomedicine, Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China.,Institute of Biology, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China.,Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Yuanyuan Zhang
- Westlake Laboratory of Life Sciences and Biomedicine, Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China.,Institute of Biology, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China
| | - Renhong Yan
- Westlake Laboratory of Life Sciences and Biomedicine, Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China.,Institute of Biology, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China.,Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Bangdong Huang
- Westlake Laboratory of Life Sciences and Biomedicine, Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China.,Institute of Biology, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China
| | - Fangfei Ye
- Westlake Laboratory of Life Sciences and Biomedicine, Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China.,Institute of Biology, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China
| | - Liushu Wu
- Westlake Laboratory of Life Sciences and Biomedicine, Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China.,Institute of Biology, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China
| | - Ximin Chi
- Westlake Laboratory of Life Sciences and Biomedicine, Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China.,Institute of Biology, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China
| | - Yi Shi
- Westlake Laboratory of Life Sciences and Biomedicine, Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China.,Institute of Biology, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China
| | - Qiang Zhou
- Westlake Laboratory of Life Sciences and Biomedicine, Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China. .,Institute of Biology, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou, 310024, Zhejiang Province, China.
| |
Collapse
|
2
|
Grønberg C, Hu Q, Mahato DR, Longhin E, Salustros N, Duelli A, Lyu P, Bågenholm V, Eriksson J, Rao KU, Henderson DI, Meloni G, Andersson M, Croll T, Godaly G, Wang K, Gourdon P. Structure and ion-release mechanism of P IB-4-type ATPases. eLife 2021; 10:73124. [PMID: 34951590 PMCID: PMC8880997 DOI: 10.7554/elife.73124] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 12/17/2021] [Indexed: 11/13/2022] Open
Abstract
Transition metals, such as zinc, are essential micronutrients in all organisms, but also highly toxic in excessive amounts. Heavy-metal transporting P-type (PIB) ATPases are crucial for homeostasis, conferring cellular detoxification and redistribution through transport of these ions across cellular membranes. No structural information is available for the PIB-4-ATPases, the subclass with the broadest cargo scope, and hence even their topology remains elusive. Here we present structures and complementary functional analyses of an archetypal PIB‑4‑ATPase, sCoaT from Sulfitobacter sp. NAS14-1. The data disclose the architecture, devoid of classical so-called heavy metal binding domains, and provides fundamentally new insights into the mechanism and diversity of heavy-metal transporters. We reveal several novel P-type ATPase features, including a dual role in heavy-metal release and as an internal counter ion of an invariant histidine. We also establish that the turn-over of PIB‑ATPases is potassium independent, contrasting to many other P-type ATPases. Combined with new inhibitory compounds, our results open up for efforts in e.g. drug discovery, since PIB-4-ATPases function as virulence factors in many pathogens.
Collapse
Affiliation(s)
- Christina Grønberg
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | - Qiaoxia Hu
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Elena Longhin
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nina Salustros
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | - Annette Duelli
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | - Pin Lyu
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | - Viktoria Bågenholm
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | | | | | | | - Gabriele Meloni
- Department of Chemistry and Biochemistry, The University of Texas at Dallas, Richardson, United States
| | | | - Tristan Croll
- Department of Haematology, University of Cambridge, Cambridge, United Kingdom
| | - Gabriela Godaly
- Department of Laboratory Medicine, Umeå University, Umeå, Sweden
| | - Kaituo Wang
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | - Pontus Gourdon
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen N, Denmark
| |
Collapse
|
3
|
Prange L, Pratt M, Herman K, Schiffmann R, Mueller DM, McLean M, Mendez MM, Walley N, Heinzen EL, Goldstein D, Shashi V, Hunanyan A, Pagadala V, Mikati MA. D-DEMØ, a distinct phenotype caused by ATP1A3 mutations. NEUROLOGY-GENETICS 2020; 6:e466. [PMID: 32802951 PMCID: PMC7413631 DOI: 10.1212/nxg.0000000000000466] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 05/18/2020] [Indexed: 11/15/2022]
Abstract
Objective To describe a phenotype caused by ATP1A3 mutations, which manifests as dystonia, dysmorphism of the face, encephalopathy with developmental delay, brain MRI abnormalities always including cerebellar hypoplasia, no hemiplegia (Ø) (D-DEMØ), and neonatal onset. Methods Review and analysis of clinical and genetic data. Results Patients shared the above traits and had whole-exome sequencing that showed de novo variants of the ATP1A3 gene, predicted to be disease causing and occurring in regions of the protein critical for pump function. Patient 1 (c.1079C>G, p.Thr360Arg), an 8-year-old girl, presented on day 1 of life with episodic dystonia, complex partial seizures, and facial dysmorphism. MRI of the brain revealed cerebellar hypoplasia. Patient 2 (c.420G>T, p.Gln140His), an 18-year-old man, presented on day 1 of life with hypotonia, tremor, and facial dysmorphism. He later developed dystonia. MRI of the brain revealed cerebellar hypoplasia and, later, further cerebellar volume loss (atrophy). Patient 3 (c.974G>A, Gly325Asp), a 13-year-old girl, presented on day 1 of life with tremor, episodic dystonia, and facial dysmorphism. MRI of the brain showed severe cerebellar hypoplasia. Patient 4 (c.971A>G, p.Glu324Gly), a 14-year-old boy, presented on day 1 of life with tremor, hypotonia, dystonia, nystagmus, facial dysmorphism, and later seizures. MRI of the brain revealed moderate cerebellar hypoplasia. Conclusions D-DEMØ represents an ATP1A3-related phenotype, the observation of which should trigger investigation for ATP1A3 mutations. Our findings, and the presence of multiple distinct ATP1A3-related phenotypes, support the possibility that there are differences in the underlying mechanisms.
Collapse
Affiliation(s)
- Lyndsey Prange
- Duke University (L.P., M.P., M.M.M., N.W., V.S., A.H., M.A.M.), Durham, NC; UC Davis Health (K.H.), Sacramento; Baylor Scott & White Health (R.S.), Dallas, TX; Rosalind Franklin University of Medicine and Science (D.M.M.), Chicago, IL; University of North Carolina at Chapel Hill (E.L.H.); Columbia University (D.G.), New York City, NY; and Glycan Therapeutics, LLC (V.P.), Chapel Hill, NC
| | - Milton Pratt
- Duke University (L.P., M.P., M.M.M., N.W., V.S., A.H., M.A.M.), Durham, NC; UC Davis Health (K.H.), Sacramento; Baylor Scott & White Health (R.S.), Dallas, TX; Rosalind Franklin University of Medicine and Science (D.M.M.), Chicago, IL; University of North Carolina at Chapel Hill (E.L.H.); Columbia University (D.G.), New York City, NY; and Glycan Therapeutics, LLC (V.P.), Chapel Hill, NC
| | - Kristin Herman
- Duke University (L.P., M.P., M.M.M., N.W., V.S., A.H., M.A.M.), Durham, NC; UC Davis Health (K.H.), Sacramento; Baylor Scott & White Health (R.S.), Dallas, TX; Rosalind Franklin University of Medicine and Science (D.M.M.), Chicago, IL; University of North Carolina at Chapel Hill (E.L.H.); Columbia University (D.G.), New York City, NY; and Glycan Therapeutics, LLC (V.P.), Chapel Hill, NC
| | - Raphael Schiffmann
- Duke University (L.P., M.P., M.M.M., N.W., V.S., A.H., M.A.M.), Durham, NC; UC Davis Health (K.H.), Sacramento; Baylor Scott & White Health (R.S.), Dallas, TX; Rosalind Franklin University of Medicine and Science (D.M.M.), Chicago, IL; University of North Carolina at Chapel Hill (E.L.H.); Columbia University (D.G.), New York City, NY; and Glycan Therapeutics, LLC (V.P.), Chapel Hill, NC
| | - David M Mueller
- Duke University (L.P., M.P., M.M.M., N.W., V.S., A.H., M.A.M.), Durham, NC; UC Davis Health (K.H.), Sacramento; Baylor Scott & White Health (R.S.), Dallas, TX; Rosalind Franklin University of Medicine and Science (D.M.M.), Chicago, IL; University of North Carolina at Chapel Hill (E.L.H.); Columbia University (D.G.), New York City, NY; and Glycan Therapeutics, LLC (V.P.), Chapel Hill, NC
| | - Melissa McLean
- Duke University (L.P., M.P., M.M.M., N.W., V.S., A.H., M.A.M.), Durham, NC; UC Davis Health (K.H.), Sacramento; Baylor Scott & White Health (R.S.), Dallas, TX; Rosalind Franklin University of Medicine and Science (D.M.M.), Chicago, IL; University of North Carolina at Chapel Hill (E.L.H.); Columbia University (D.G.), New York City, NY; and Glycan Therapeutics, LLC (V.P.), Chapel Hill, NC
| | - Mary Moya Mendez
- Duke University (L.P., M.P., M.M.M., N.W., V.S., A.H., M.A.M.), Durham, NC; UC Davis Health (K.H.), Sacramento; Baylor Scott & White Health (R.S.), Dallas, TX; Rosalind Franklin University of Medicine and Science (D.M.M.), Chicago, IL; University of North Carolina at Chapel Hill (E.L.H.); Columbia University (D.G.), New York City, NY; and Glycan Therapeutics, LLC (V.P.), Chapel Hill, NC
| | - Nicole Walley
- Duke University (L.P., M.P., M.M.M., N.W., V.S., A.H., M.A.M.), Durham, NC; UC Davis Health (K.H.), Sacramento; Baylor Scott & White Health (R.S.), Dallas, TX; Rosalind Franklin University of Medicine and Science (D.M.M.), Chicago, IL; University of North Carolina at Chapel Hill (E.L.H.); Columbia University (D.G.), New York City, NY; and Glycan Therapeutics, LLC (V.P.), Chapel Hill, NC
| | - Erin L Heinzen
- Duke University (L.P., M.P., M.M.M., N.W., V.S., A.H., M.A.M.), Durham, NC; UC Davis Health (K.H.), Sacramento; Baylor Scott & White Health (R.S.), Dallas, TX; Rosalind Franklin University of Medicine and Science (D.M.M.), Chicago, IL; University of North Carolina at Chapel Hill (E.L.H.); Columbia University (D.G.), New York City, NY; and Glycan Therapeutics, LLC (V.P.), Chapel Hill, NC
| | - David Goldstein
- Duke University (L.P., M.P., M.M.M., N.W., V.S., A.H., M.A.M.), Durham, NC; UC Davis Health (K.H.), Sacramento; Baylor Scott & White Health (R.S.), Dallas, TX; Rosalind Franklin University of Medicine and Science (D.M.M.), Chicago, IL; University of North Carolina at Chapel Hill (E.L.H.); Columbia University (D.G.), New York City, NY; and Glycan Therapeutics, LLC (V.P.), Chapel Hill, NC
| | - Vandana Shashi
- Duke University (L.P., M.P., M.M.M., N.W., V.S., A.H., M.A.M.), Durham, NC; UC Davis Health (K.H.), Sacramento; Baylor Scott & White Health (R.S.), Dallas, TX; Rosalind Franklin University of Medicine and Science (D.M.M.), Chicago, IL; University of North Carolina at Chapel Hill (E.L.H.); Columbia University (D.G.), New York City, NY; and Glycan Therapeutics, LLC (V.P.), Chapel Hill, NC
| | - Arsen Hunanyan
- Duke University (L.P., M.P., M.M.M., N.W., V.S., A.H., M.A.M.), Durham, NC; UC Davis Health (K.H.), Sacramento; Baylor Scott & White Health (R.S.), Dallas, TX; Rosalind Franklin University of Medicine and Science (D.M.M.), Chicago, IL; University of North Carolina at Chapel Hill (E.L.H.); Columbia University (D.G.), New York City, NY; and Glycan Therapeutics, LLC (V.P.), Chapel Hill, NC
| | - Vijay Pagadala
- Duke University (L.P., M.P., M.M.M., N.W., V.S., A.H., M.A.M.), Durham, NC; UC Davis Health (K.H.), Sacramento; Baylor Scott & White Health (R.S.), Dallas, TX; Rosalind Franklin University of Medicine and Science (D.M.M.), Chicago, IL; University of North Carolina at Chapel Hill (E.L.H.); Columbia University (D.G.), New York City, NY; and Glycan Therapeutics, LLC (V.P.), Chapel Hill, NC
| | - Mohamad A Mikati
- Duke University (L.P., M.P., M.M.M., N.W., V.S., A.H., M.A.M.), Durham, NC; UC Davis Health (K.H.), Sacramento; Baylor Scott & White Health (R.S.), Dallas, TX; Rosalind Franklin University of Medicine and Science (D.M.M.), Chicago, IL; University of North Carolina at Chapel Hill (E.L.H.); Columbia University (D.G.), New York City, NY; and Glycan Therapeutics, LLC (V.P.), Chapel Hill, NC
| |
Collapse
|
4
|
Sørensen DM, Holen HW, Pedersen JT, Martens HJ, Silvestro D, Stanchev LD, Costa SR, Günther Pomorski T, López-Marqués RL, Palmgren M. The P5A ATPase Spf1p is stimulated by phosphatidylinositol 4-phosphate and influences cellular sterol homeostasis. Mol Biol Cell 2019; 30:1069-1084. [PMID: 30785834 PMCID: PMC6724510 DOI: 10.1091/mbc.e18-06-0365] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
P5A ATPases are expressed in the endoplasmic reticulum (ER) of all eukaryotic cells, and their disruption results in severe ER stress. However, the function of these ubiquitous membrane proteins, which belong to the P-type ATPase superfamily, is unknown. We purified a functional tagged version of the Saccharomyces cerevisiae P5A ATPase Spf1p and observed that the ATP hydrolytic activity of the protein is stimulated by phosphatidylinositol 4-phosphate (PI4P). Furthermore, SPF1 exhibited negative genetic interactions with SAC1, encoding a PI4P phosphatase, and with OSH1 to OSH6, encoding Osh proteins, which, when energized by a PI4P gradient, drive export of sterols and lipids from the ER. Deletion of SPF1 resulted in increased sensitivity to inhibitors of sterol production, a marked change in the ergosterol/lanosterol ratio, accumulation of sterols in the plasma membrane, and cytosolic accumulation of lipid bodies. We propose that Spf1p maintains cellular sterol homeostasis by influencing the PI4P-induced and Osh-mediated export of sterols from the ER.
Collapse
Affiliation(s)
- Danny Mollerup Sørensen
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Henrik Waldal Holen
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Jesper Torbøl Pedersen
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Helle Juel Martens
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Daniele Silvestro
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Lyubomir Dimitrov Stanchev
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Sara Rute Costa
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Thomas Günther Pomorski
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Rosa Laura López-Marqués
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| | - Michael Palmgren
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark
| |
Collapse
|
5
|
Monti JLE, Montes MR, Rossi RC. Steady-state analysis of enzymes with non-Michaelis-Menten kinetics: The transport mechanism of Na +/K +-ATPase. J Biol Chem 2017; 293:1373-1385. [PMID: 29191836 DOI: 10.1074/jbc.m117.799536] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 11/29/2017] [Indexed: 11/06/2022] Open
Abstract
Procedures to define kinetic mechanisms from catalytic activity measurements that obey the Michaelis-Menten equation are well established. In contrast, analytical tools for enzymes displaying non-Michaelis-Menten kinetics are underdeveloped, and transient-state measurements, when feasible, are therefore preferred in kinetic studies. Of note, transient-state determinations evaluate only partial reactions, and these might not participate in the reaction cycle. Here, we provide a general procedure to characterize kinetic mechanisms from steady-state determinations. We described non-Michaelis-Menten kinetics with equations containing parameters equivalent to kcat and Km and modeled the underlying mechanism by an approach similar to that used under Michaelis-Menten kinetics. The procedure enabled us to evaluate whether Na+/K+-ATPase uses the same sites to alternatively transport Na+ and K+ This ping-pong mechanism is supported by transient-state studies but contradicted to date by steady-state analyses claiming that the release of one cationic species as product requires the binding of the other (ternary-complex mechanism). To derive robust conclusions about the Na+/K+-ATPase transport mechanism, we did not rely on ATPase activity measurements alone. During the catalytic cycle, the transported cations become transitorily occluded (i.e. trapped within the enzyme). We employed radioactive isotopes to quantify occluded cations under steady-state conditions. We replaced K+ with Rb+ because 42K+ has a short half-life, and previous studies showed that K+- and Rb+-occluded reaction intermediates are similar. We derived conclusions regarding the rate of Rb+ deocclusion that were verified by direct measurements. Our results validated the ping-pong mechanism and proved that Rb+ deocclusion is accelerated when Na+ binds to an allosteric, nonspecific site, leading to a 2-fold increase in ATPase activity.
Collapse
Affiliation(s)
- José L E Monti
- From the Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, 1053 Buenos Aires, Argentina and .,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), 1053 Buenos Aires, Argentina
| | - Mónica R Montes
- From the Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, 1053 Buenos Aires, Argentina and.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), 1053 Buenos Aires, Argentina
| | - Rolando C Rossi
- From the Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, 1053 Buenos Aires, Argentina and.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), 1053 Buenos Aires, Argentina
| |
Collapse
|
6
|
Boo MV, Hiong KC, Choo CYL, Cao-Pham AH, Wong WP, Chew SF, Ip YK. The inner mantle of the giant clam, Tridacna squamosa, expresses a basolateral Na+/K+-ATPase α-subunit, which displays light-dependent gene and protein expression along the shell-facing epithelium. PLoS One 2017; 12:e0186865. [PMID: 29049367 PMCID: PMC5648256 DOI: 10.1371/journal.pone.0186865] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 10/09/2017] [Indexed: 12/11/2022] Open
Abstract
Na+/K+-ATPase (NKA) is essential for maintaining the Na+ and K+ gradients, and supporting the secondary active transport of certain ions/molecules, across the plasma membrane of animal cells. This study aimed to clone the NKA α-subunit (NKAα) from the inner mantle adjacent to the extrapallial fluid of Tridacna squamosa, to determine its subcellular localization, and to examine the effects of light exposure on its transcript level and protein abundance. The cDNA coding sequence of NKAα from T. squamosa comprised 3105 bp, encoding 1034 amino acids with an estimated molecular mass of 114 kDa. NKAα had a basolateral localization along the shell-facing epithelium of the inner mantle. Exposure to 12 h of light led to a significantly stronger basolateral NKAα-immunofluorescence at the shell-facing epithelium, indicating that NKA might play a role in light-enhanced calcification in T. squamosa. After 3 h of light exposure, the transcript level of NKAα decreased transiently in the inner mantle, but returned to the control level thereafter. In comparison, the protein abundance of NKAα remained unchanged at hour 3, but became significantly higher than the control after 12 h of light exposure. Hence, the expression of NKAα in the inner mantle of T. squamosa was light-dependent. It is probable that a higher expression level of NKA was needed in the shell-facing epithelial cells of the inner mantle to cope with a rise in Na+ influx, possibly caused by increases in activities of some Na+-dependent ion transporters/channels involved in light-enhanced calcification.
Collapse
Affiliation(s)
- Mel V. Boo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore
| | - Kum C. Hiong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore
| | - Celine Y. L. Choo
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore
| | - Anh H. Cao-Pham
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore
| | - Wai P. Wong
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore
| | - Shit F. Chew
- Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore, Republic of Singapore
| | - Yuen K. Ip
- Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore
- The Tropical Marine Science Institute, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore
- * E-mail:
| |
Collapse
|
7
|
Kubala M, Čechová P, Geletičová J, Biler M, Štenclová T, Trouillas P, Biedermann D. Flavonolignans As a Novel Class of Sodium Pump Inhibitors. Front Physiol 2016; 7:115. [PMID: 27065883 PMCID: PMC4812144 DOI: 10.3389/fphys.2016.00115] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 03/14/2016] [Indexed: 11/13/2022] Open
Abstract
We examined the inhibitory effects of three flavonolignans and their dehydro- derivatives, taxifolin and quercetin on the activity of the Na+/K+-ATPase (NKA). The flavonolignans silychristin, dehydrosilychristin and dehydrosilydianin inhibited NKA with IC50 of 110 ± 40 μM, 38 ± 8 μM, and 36 ± 14 μM, respectively. Using the methods of molecular modeling, we identified several possible binding sites for these species on NKA and proposed the possible mechanisms of inhibition. The binding to the extracellular- or cytoplasmic C-terminal sites can block the transport of cations through the plasma membrane, while the binding on the interface of cytoplasmic domains can inhibit the enzyme allosterically. Fluorescence spectroscopy experiments confirmed the interaction of these three species with the large cytoplasmic segment connecting transmembrane helices 4 and 5 (C45). The flavonolignans are distinct from the cardiac glycosides that are currently used in NKA treatment. Because their binding sites are different, the mechanism of inhibition is different as well as the range of active concentrations, one can expect that these new NKA inhibitors would exhibit also a different biomedical actions than cardiac glycosides.
Collapse
Affiliation(s)
- Martin Kubala
- Department of Biophysics, Faculty of Science, Centre of Region Haná for Biotechnological and Agricultural Research, Palacký University Olomouc, Czech Republic
| | - Petra Čechová
- Department of Biophysics, Faculty of Science, Centre of Region Haná for Biotechnological and Agricultural Research, Palacký University Olomouc, Czech Republic
| | - Jaroslava Geletičová
- Department of Biophysics, Faculty of Science, Centre of Region Haná for Biotechnological and Agricultural Research, Palacký University Olomouc, Czech Republic
| | - Michal Biler
- Department of Biophysics, Faculty of Science, Centre of Region Haná for Biotechnological and Agricultural Research, Palacký UniversityOlomouc, Czech Republic; INSERM UMR 850, School of Pharmacy, University LimogesLimoges, France
| | - Tereza Štenclová
- Department of Biophysics, Faculty of Science, Centre of Region Haná for Biotechnological and Agricultural Research, Palacký University Olomouc, Czech Republic
| | - Patrick Trouillas
- INSERM UMR 850, School of Pharmacy, University LimogesLimoges, France; Department of Physical Chemistry, Faculty of Science, Regional Centre of Advanced Technologies and Materials, Palacký UniversityOlomouc, Czech Republic
| | - David Biedermann
- Laboratory of Biotransformation, Institute of Microbiology, Czech Academy of Sciences Prague, Czech Republic
| |
Collapse
|
8
|
Sequential substitution of K(+) bound to Na(+),K(+)-ATPase visualized by X-ray crystallography. Nat Commun 2015; 6:8004. [PMID: 26258479 PMCID: PMC4918401 DOI: 10.1038/ncomms9004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 07/02/2015] [Indexed: 11/08/2022] Open
Abstract
Na+,K+-ATPase transfers three Na+ from the cytoplasm into the extracellular medium and two K+ in the opposite direction per ATP hydrolysed. The binding and release of Na+ and K+ are all thought to occur sequentially. Here we demonstrate by X-ray crystallography of the ATPase in E2·MgF42−·2K+, a state analogous to E2·Pi·2K+, combined with isotopic measurements, that the substitution of the two K+ with congeners in the extracellular medium indeed occurs at different rates, substantially faster at site II. An analysis of thermal movements of protein atoms in the crystal shows that the M3–M4E helix pair opens and closes the ion pathway leading to the extracellular medium, allowing K+ at site II to be substituted first. Taken together, these results indicate that site I K+ is the first cation to bind to the empty cation-binding sites after releasing three Na+. The Na+,K+-ATPase moves three Na+ ions out of the cell and transfers two K+ ions in the opposite direction. Here the authors use X-ray crystallography to look at the substitution of two bound K+ with those in the medium and show that it occurs sequentially through a narrow gate.
Collapse
|
9
|
Khundmiri SJ. Advances in understanding the role of cardiac glycosides in control of sodium transport in renal tubules. J Endocrinol 2014; 222:R11-24. [PMID: 24781255 DOI: 10.1530/joe-13-0613] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cardiotonic steroids have been used for the past 200 years in the treatment of congestive heart failure. As specific inhibitors of membrane-bound Na(+)/K(+) ATPase, they enhance cardiac contractility through increasing myocardial cell calcium concentration in response to the resulting increase in intracellular Na concentration. The half-minimal concentrations of cardiotonic steroids required to inhibit Na(+)/K(+) ATPase range from nanomolar to micromolar concentrations. In contrast, the circulating levels of cardiotonic steroids under physiological conditions are in the low picomolar concentration range in healthy subjects, increasing to high picomolar levels under pathophysiological conditions including chronic kidney disease and heart failure. Little is known about the physiological function of low picomolar concentrations of cardiotonic steroids. Recent studies have indicated that physiological concentrations of cardiotonic steroids acutely stimulate the activity of Na(+)/K(+) ATPase and activate an intracellular signaling pathway that regulates a variety of intracellular functions including cell growth and hypertrophy. The effects of circulating cardiotonic steroids on renal salt handling and total body sodium homeostasis are unknown. This review will focus on the role of low picomolar concentrations of cardiotonic steroids in renal Na(+)/K(+) ATPase activity, cell signaling, and blood pressure regulation.
Collapse
Affiliation(s)
- Syed Jalal Khundmiri
- Division of Nephrology and HypertensionDepartment of MedicineDepartment of Physiology and BiophysicsUniversity of Louisville, 570 S. Preston Street, Louisville, Kentucky 40202, USADivision of Nephrology and HypertensionDepartment of MedicineDepartment of Physiology and BiophysicsUniversity of Louisville, 570 S. Preston Street, Louisville, Kentucky 40202, USA
| |
Collapse
|
10
|
Teo I, Schulten K. A computational kinetic model of diffusion for molecular systems. J Chem Phys 2014; 139:121929. [PMID: 24089741 DOI: 10.1063/1.4820876] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Regulation of biomolecular transport in cells involves intra-protein steps like gating and passage through channels, but these steps are preceded by extra-protein steps, namely, diffusive approach and admittance of solutes. The extra-protein steps develop over a 10-100 nm length scale typically in a highly particular environment, characterized through the protein's geometry, surrounding electrostatic field, and location. In order to account for solute energetics and mobility of solutes in this environment at a relevant resolution, we propose a particle-based kinetic model of diffusion based on a Markov State Model framework. Prerequisite input data consist of diffusion coefficient and potential of mean force maps generated from extensive molecular dynamics simulations of proteins and their environment that sample multi-nanosecond durations. The suggested diffusion model can describe transport processes beyond microsecond duration, relevant for biological function and beyond the realm of molecular dynamics simulation. For this purpose the systems are represented by a discrete set of states specified by the positions, volumes, and surface elements of Voronoi grid cells distributed according to a density function resolving the often intricate relevant diffusion space. Validation tests carried out for generic diffusion spaces show that the model and the associated Brownian motion algorithm are viable over a large range of parameter values such as time step, diffusion coefficient, and grid density. A concrete application of the method is demonstrated for ion diffusion around and through the Eschericia coli mechanosensitive channel of small conductance ecMscS.
Collapse
Affiliation(s)
- Ivan Teo
- Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, Illinois 61801, USA
| | | |
Collapse
|
11
|
Zhitnitsky D, Lewinson O. Identification of functionally important conserved trans-membrane residues of bacterial PIB -type ATPases. Mol Microbiol 2014; 91:777-89. [PMID: 24350798 PMCID: PMC4285229 DOI: 10.1111/mmi.12495] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2013] [Indexed: 01/23/2023]
Abstract
Powered by ATP hydrolysis, PIB-ATPases drive the energetically uphill transport of transition metals. These high affinity pumps are essential for heavy metal detoxification and delivery of metal cofactors to specific cellular compartments. Amino acid sequence alignment of the trans-membrane (TM) helices of PIB-ATPases reveals a high degree of conservation, with ∼60–70 fully conserved positions. Of these conserved positions, 6–7 were previously identified to be important for transport. However, the functional importance of the majority of the conserved TM residues remains unclear. To investigate the role of conserved TM residues of PIB-ATPases we conducted an extensive mutagenesis study of a Zn2+ Cd2+ PIB-ATPase from Rhizobium radiobacter (rrZntA) and seven other PIB-ATPases. Of the 38 conserved positions tested, 24 had small effects on metal tolerance. Fourteen mutations compromised in vivo metal tolerance and in vitro metal-stimulated ATPase activity. Based on structural modelling, the functionally important residues line a constricted ‘channel’, tightly surrounded by the residues that were found to be inconsequential for function. We tentatively propose that the distribution of the mutable and immutable residues marks a possible trans-membrane metal translocation pathway. In addition, by substituting six trans-membrane amino acids of rrZntA we changed the in vivo metal specificity of this pump from Zn2+ Cd2+ to Ag+.
Collapse
Affiliation(s)
- Daniel Zhitnitsky
- Department of Microbiology, The Bruce and Ruth Rappaport Faculty of Medicine, The Technion-Israel Institute of Technology, Haifa, Israel
| | | |
Collapse
|
12
|
Henriksen C, Kjaer-Sorensen K, Einholm AP, Madsen LB, Momeni J, Bendixen C, Oxvig C, Vilsen B, Larsen K. Molecular cloning and characterization of porcine Na⁺/K⁺-ATPase isoforms α1, α2, α3 and the ATP1A3 promoter. PLoS One 2013; 8:e79127. [PMID: 24236096 PMCID: PMC3827302 DOI: 10.1371/journal.pone.0079127] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 09/17/2013] [Indexed: 11/18/2022] Open
Abstract
Na⁺/K⁺-ATPase maintains electrochemical gradients of Na⁺ and K⁺ essential for a variety of cellular functions including neuronal activity. The α-subunit of the Na⁺/K⁺-ATPase exists in four different isoforms (α1-α4) encoded by different genes. With a view to future use of pig as an animal model in studies of human diseases caused by Na⁺/K⁺-ATPase mutations, we have determined the porcine coding sequences of the α1-α3 genes, ATP1A1, ATP1A2, and ATP1A3, their chromosomal localization, and expression patterns. Our ATP1A1 sequence accords with the sequences from several species at five positions where the amino acid residue of the previously published porcine ATP1A1 sequence differs. These corrections include replacement of glutamine 841 with arginine. Analysis of the functional consequences of substitution of the arginine revealed its importance for Na⁺ binding, which can be explained by interaction of the arginine with the C-terminus, stabilizing one of the Na⁺ sites. Quantitative real-time PCR expression analyses of porcine ATP1A1, ATP1A2, and ATP1A3 mRNA showed that all three transcripts are expressed in the embryonic brain as early as 60 days of gestation. Expression of α3 is confined to neuronal tissue. Generally, the expression patterns of ATP1A1, ATP1A2, and ATP1A3 transcripts were found similar to their human counterparts, except for lack of α3 expression in porcine heart. These expression patterns were confirmed at the protein level. We also report the sequence of the porcine ATP1A3 promoter, which was found to be closely homologous to its human counterpart. The function and specificity of the porcine ATP1A3 promoter was analyzed in transgenic zebrafish, demonstrating that it is active and drives expression in embryonic brain and spinal cord. The results of the present study provide a sound basis for employing the ATP1A3 promoter in attempts to generate transgenic porcine models of neurological diseases caused by ATP1A3 mutations.
Collapse
Affiliation(s)
- Carina Henriksen
- Department of Molecular Biology and Genetics, Aarhus University, Tjele, Denmark
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | | | | | - Lone Bruhn Madsen
- Department of Molecular Biology and Genetics, Aarhus University, Tjele, Denmark
| | - Jamal Momeni
- Department of Molecular Biology and Genetics, Aarhus University, Tjele, Denmark
| | - Christian Bendixen
- Department of Molecular Biology and Genetics, Aarhus University, Tjele, Denmark
| | - Claus Oxvig
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C, Denmark
| | - Bente Vilsen
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Knud Larsen
- Department of Molecular Biology and Genetics, Aarhus University, Tjele, Denmark
- * E-mail:
| |
Collapse
|
13
|
Crystal structure of a Na+-bound Na+,K+-ATPase preceding the E1P state. Nature 2013; 502:201-6. [PMID: 24089211 DOI: 10.1038/nature12578] [Citation(s) in RCA: 225] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 08/16/2013] [Indexed: 11/08/2022]
Abstract
Na(+),K(+)-ATPase pumps three Na(+) ions out of cells in exchange for two K(+) taken up from the extracellular medium per ATP molecule hydrolysed, thereby establishing Na(+) and K(+) gradients across the membrane in all animal cells. These ion gradients are used in many fundamental processes, notably excitation of nerve cells. Here we describe 2.8 Å-resolution crystal structures of this ATPase from pig kidney with bound Na(+), ADP and aluminium fluoride, a stable phosphate analogue, with and without oligomycin that promotes Na(+) occlusion. These crystal structures represent a transition state preceding the phosphorylated intermediate (E1P) in which three Na(+) ions are occluded. Details of the Na(+)-binding sites show how this ATPase functions as a Na(+)-specific pump, rejecting K(+) and Ca(2+), even though its affinity for Na(+) is low (millimolar dissociation constant). A mechanism for sequential, cooperative Na(+) binding can now be formulated in atomic detail.
Collapse
|
14
|
Alternative cycling modes of the Na(+)/K(+)-ATPase in the presence of either Na(+) or Rb(+). BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1374-83. [PMID: 23357355 DOI: 10.1016/j.bbamem.2013.01.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Revised: 01/10/2013] [Accepted: 01/15/2013] [Indexed: 11/23/2022]
Abstract
A comprehensive study of the interaction between Na(+) and K(+) with the Na(+)/K(+)-ATPase requires dissecting the incidence of alternative cycling modes on activity measurements in which one or both of these cations are absent. With this aim, we used membrane fragments containing pig-kidney Na(+)/K(+)-ATPase to perform measurements, at 25°C and pH=7.4, of ATPase activity and steady-state levels of (i) intermediates containing occluded Rb(+) at different [Rb(+)] in media lacking Na(+), and (ii) phosphorylated intermediates at different [Na(+)] in media lacking Rb(+). Most relevant results are: (1) Rb(+) can be occluded through an ATPasic cycling mode that takes place in the absence of Na(+) ions, (2) the kinetic behavior of the phosphoenzyme formed by ATP in the absence of Na(+) is different from the one that is formed with Na(+), and (3) binding of Na(+) to transport sites during catalysis is not at random unless rapid equilibrium holds.
Collapse
|
15
|
Garçon DP, Lucena MN, Pinto MR, Fontes CFL, McNamara JC, Leone FA. Synergistic stimulation by potassium and ammonium of K(+)-phosphatase activity in gill microsomes from the crab Callinectes ornatus acclimated to low salinity: novel property of a primordial pump. Arch Biochem Biophys 2012; 530:55-63. [PMID: 23262318 DOI: 10.1016/j.abb.2012.12.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 11/28/2012] [Accepted: 12/04/2012] [Indexed: 11/16/2022]
Abstract
We provide an extensive characterization of the modulation by p-nitrophenylphosphate, Mg²⁺, Na⁺, K(+), Rb⁺, NH(4)(+) and pH of gill microsomal K⁺-phosphatase activity in the posterior gills of Callinectes ornatus acclimated to low salinity (21‰). The synergistic stimulation by K⁺ and NH(4)(+) of the K⁺-phosphatase activity is a novel finding, and may constitute a species-specific feature of K(+)/NH(4)(+) interplay that regulates crustacean gill (Na⁺, K⁺)-ATPase activity. p-Nitrophenylphosphate was hydrolyzed at a maximum rate (V) of 69.2 ± 2.8nmolPimin⁻¹mg⁻¹ with K(0.5)=2.3 ± 0.1mmolL(-1), obeying cooperative kinetics (n(H)=1.7). Stimulation by Mg²⁺ (V=70.1 ± 3.0nmolPimin⁻¹mg⁻¹, K(0.5)=0.88 ± 0.04mmolL⁻¹), K⁺ (V=69.6 ± 2.7nmolPimin⁻¹mg⁻¹, K(0.5)=1.60 ± 0.07mmolL⁻¹) and NH(4)(+) (V=90.8 ± 4.0nmolPimin⁻¹mg⁻¹, K(0.5)=9.2 ± 0.3mmol L⁻¹) all displayed site-site interaction kinetics. In the presence of NH(4)(+), enzyme affinity for K⁺ unexpectedly increased by 7-fold, while affinity for NH(4)(+) was 28-fold greater in the presence than absence of K⁺. Ouabain partially inhibited K⁺-phosphatase activity (K(I)=320 ± 14.0μmolL⁻¹), more effectively when NH(4)(+) was present (K(I)=240 ± 12.0μmolL⁻¹). We propose a model for the synergistic stimulation by K⁺ and NH(4)(+) of the K⁺-phosphatase activity of the (Na⁺, K⁺)-ATPase from C. ornatus posterior gill tissue.
Collapse
Affiliation(s)
- Daniela P Garçon
- Departamento de Biologia Molecular, Centro de Ciências Exatas e da Natureza, Universidade Federal da Paraíba, Brazil
| | | | | | | | | | | |
Collapse
|
16
|
Kaufman SB, González-Flecha FL, González-Lebrero RM. Opposing Effects of Na+ and K+ on the Thermal Stability of Na+,K+-ATPase. J Phys Chem B 2012; 116:3421-9. [DOI: 10.1021/jp2124108] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Sergio B. Kaufman
- Instituto
de Química y Fisicoquímica
Biológicas and Departamento de Química Biológica,
Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - F. Luis González-Flecha
- Instituto
de Química y Fisicoquímica
Biológicas and Departamento de Química Biológica,
Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Rodolfo M. González-Lebrero
- Instituto
de Química y Fisicoquímica
Biológicas and Departamento de Química Biológica,
Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| |
Collapse
|
17
|
Affiliation(s)
- Michael G. Palmgren
- Center for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, University of Copenhagen, DK-1871 Frederiksberg C, Denmark;
| | - Poul Nissen
- Center for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus University, DK-8000 Århus C, Denmark;
| |
Collapse
|
18
|
Abstract
The sarcoplasmic (SERCA 1a) Ca2+-ATPase is a membrane protein abundantly present in skeletal muscles where it functions as an indispensable component of the excitation-contraction coupling, being at the expense of ATP hydrolysis involved in Ca2+/H+ exchange with a high thermodynamic efficiency across the sarcoplasmic reticulum membrane. The transporter serves as a prototype of a whole family of cation transporters, the P-type ATPases, which in addition to Ca2+ transporting proteins count Na+, K+-ATPase and H+, K+-, proton- and heavy metal transporting ATPases as prominent members. The ability in recent years to produce and analyze at atomic (2·3-3 Å) resolution 3D-crystals of Ca2+-transport intermediates of SERCA 1a has meant a breakthrough in our understanding of the structural aspects of the transport mechanism. We describe here the detailed construction of the ATPase in terms of one membraneous and three cytosolic domains held together by a central core that mediates coupling between Ca2+-transport and ATP hydrolysis. During turnover, the pump is present in two different conformational states, E1 and E2, with a preference for the binding of Ca2+ and H+, respectively. We discuss how phosphorylated and non-phosphorylated forms of these conformational states with cytosolic, occluded or luminally exposed cation-binding sites are able to convert the chemical energy derived from ATP hydrolysis into an electrochemical gradient of Ca2+ across the sarcoplasmic reticulum membrane. In conjunction with these basic reactions which serve as a structural framework for the transport function of other P-type ATPases as well, we also review the role of the lipid phase and the regulatory and thermodynamic aspects of the transport mechanism.
Collapse
|
19
|
Morth JP, Pedersen BP, Buch-Pedersen MJ, Andersen JP, Vilsen B, Palmgren MG, Nissen P. A structural overview of the plasma membrane Na+,K+-ATPase and H+-ATPase ion pumps. Nat Rev Mol Cell Biol 2011; 12:60-70. [PMID: 21179061 DOI: 10.1038/nrm3031] [Citation(s) in RCA: 244] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Plasma membrane ATPases are primary active transporters of cations that maintain steep concentration gradients. The ion gradients and membrane potentials derived from them form the basis for a range of essential cellular processes, in particular Na(+)-dependent and proton-dependent secondary transport systems that are responsible for uptake and extrusion of metabolites and other ions. The ion gradients are also both directly and indirectly used to control pH homeostasis and to regulate cell volume. The plasma membrane H(+)-ATPase maintains a proton gradient in plants and fungi and the Na(+),K(+)-ATPase maintains a Na(+) and K(+) gradient in animal cells. Structural information provides insight into the function of these two distinct but related P-type pumps.
Collapse
Affiliation(s)
- J Preben Morth
- Danish National Research Foundation, Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Denmark
| | | | | | | | | | | | | |
Collapse
|
20
|
Structural identification of cation binding pockets in the plasma membrane proton pump. Proc Natl Acad Sci U S A 2010; 107:21400-5. [PMID: 21098259 DOI: 10.1073/pnas.1010416107] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The activity of P-type plasma membrane H(+)-ATPases is modulated by H(+) and cations, with K(+) and Ca(2+) being of physiological relevance. Using X-ray crystallography, we have located the binding site for Rb(+) as a K(+) congener, and for Tb(3+) and Ho(3+) as Ca(2+) congeners. Rb(+) is found coordinated by a conserved aspartate residue in the phosphorylation domain. A single Tb(3+) ion is identified positioned in the nucleotide-binding domain in close vicinity to the bound nucleotide. Ho(3+) ions are coordinated at two distinct sites within the H(+)-ATPase: One site is at the interface of the nucleotide-binding and phosphorylation domains, and the other is in the transmembrane domain toward the extracellular side. The identified binding sites are suggested to represent binding pockets for regulatory cations and a H(+) binding site for protons leaving the pump molecule. This implicates Ho(3+) as a novel chemical tool for identification of proton binding sites.
Collapse
|
21
|
Khalid M, Fouassier G, Apell HJ, Cornelius F, Clarke RJ. Interaction of ATP with the phosphoenzyme of the Na+,K+-ATPase. Biochemistry 2010; 49:1248-58. [PMID: 20063899 DOI: 10.1021/bi9019548] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The interaction of ATP with the phosphoenzyme of Na(+),K(+)-ATPase from pig kidney, rabbit kidney, and shark rectal gland was investigated using the voltage-sensitive fluorescent probe RH421. In each case, ATP concentrations >or=100 microM caused a drop in fluorescence intensity, which, because RH421 is sensitive to the formation of enzyme in the E2P state, can be attributed to ATP binding to the E2P phosphoenzyme. Simulations of the experimental behavior using kinetic models based on either a monomeric or a dimeric enzyme mechanism yielded a K(d) for ATP binding in the range 140-500 muM. Steady-state activity measurements and independent measurements of the phosphoenzyme level via a radioactive assay indicated that ATP binding to E2P causes a deceleration in its dephosphorylation when acting in the Na(+)-ATPase mode, i.e., in the absence of K(+) ions. Both the ATP-induced drop in RH421 fluorescence and the effect on the dephosphorylation reaction could be attributed to an inhibition of dissociation from the E2P(Na(+))(3) state of the one Na(+) ion necessary to allow dephosphorylation. Stopped-flow studies on the shark enzyme indicated that the ATP-induced inhibition of dephosphorylation is abolished in the presence of 1 mM KCl. A possible physiological role of allosteric binding of ATP to the phosphoenzyme could be to stabilize the E2P state and stop the enzyme running backward, which would cause dissipation of the Na(+) electrochemical potential gradient and the resynthesis of ATP from ADP. ATP binding to E2P could also fix ATP within the enzyme ready to phosphorylate it in the subsequent turnover.
Collapse
Affiliation(s)
- Mohammed Khalid
- School of Chemistry, University of Sydney, Sydney, New South Wales 2006, Australia
| | | | | | | | | |
Collapse
|
22
|
Petrushanko IY, Mitkevich VA, Borzova VA, Yakushev SS, Lopina OD, Makarov AA. Different domain organization of two main conformational states of Na+/K+-ATPase. Biophysics (Nagoya-shi) 2009. [DOI: 10.1134/s0006350909060050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
|
23
|
Babavali M, Esmann M, Fedosova NU, Marsh D. Urea-Induced Unfolding of Na,K-ATPase As Evaluated by Electron Paramagnetic Resonance Spectroscopy. Biochemistry 2009; 48:9022-30. [DOI: 10.1021/bi901124j] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mohammad Babavali
- Department of Physiology and Biophysics, Aarhus University, Aarhus, Denmark
| | - Mikael Esmann
- Department of Physiology and Biophysics, Aarhus University, Aarhus, Denmark
| | | | - Derek Marsh
- Max-Planck-Institut für biophysikalische Chemie, Abt. Spektroskopie, 37077 Göttingen, Germany
| |
Collapse
|
24
|
Crystal structure of the sodium-potassium pump at 2.4 A resolution. Nature 2009; 459:446-50. [PMID: 19458722 DOI: 10.1038/nature07939] [Citation(s) in RCA: 461] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Accepted: 02/26/2009] [Indexed: 12/14/2022]
Abstract
Sodium-potassium ATPase is an ATP-powered ion pump that establishes concentration gradients for Na(+) and K(+) ions across the plasma membrane in all animal cells by pumping Na(+) from the cytoplasm and K(+) from the extracellular medium. Such gradients are used in many essential processes, notably for generating action potentials. Na(+), K(+)-ATPase is a member of the P-type ATPases, which include sarcoplasmic reticulum Ca(2+)-ATPase and gastric H(+), K(+)-ATPase, among others, and is the target of cardiac glycosides. Here we describe a crystal structure of this important ion pump, from shark rectal glands, consisting of alpha- and beta-subunits and a regulatory FXYD protein, all of which are highly homologous to human ones. The ATPase was fixed in a state analogous to E2.2K(+).P(i), in which the ATPase has a high affinity for K(+) and still binds P(i), as in the first crystal structure of pig kidney enzyme at 3.5 A resolution. Clearly visualized now at 2.4 A resolution are coordination of K(+) and associated water molecules in the transmembrane binding sites and a phosphate analogue (MgF(4)(2-)) in the phosphorylation site. The crystal structure shows that the beta-subunit has a critical role in K(+) binding (although its involvement has previously been suggested) and explains, at least partially, why the homologous Ca(2+)-ATPase counter-transports H(+) rather than K(+), despite the coordinating residues being almost identical.
Collapse
|
25
|
Voltage clamp fluorometry: Combining fluorescence and electrophysiological methods to examine the structure–function of the Na+/K+-ATPase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:714-20. [DOI: 10.1016/j.bbabio.2009.03.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Revised: 03/29/2009] [Accepted: 03/30/2009] [Indexed: 11/23/2022]
|
26
|
Holdensen AN, Andersen JP. The length of the A-M3 linker is a crucial determinant of the rate of the Ca2+ transport cycle of sarcoplasmic reticulum Ca2+-ATPase. J Biol Chem 2009; 284:12258-65. [PMID: 19278994 DOI: 10.1074/jbc.m900977200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ion translocation by the sarcoplasmic reticulum Ca(2+)-ATPase depends on large movements of the A-domain, but the driving forces have yet to be defined. The A-domain is connected to the ion-binding membranous part of the protein through linker regions. We have determined the functional consequences of changing the length of the linker between the A-domain and transmembrane helix M3 ("A-M3 linker") by insertion and deletion mutagenesis at two sites. It was feasible to insert as many as 41 residues (polyglycine and glycine-proline loops) in the flexible region of the linker without loss of the ability to react with Ca(2+) and ATP and to form the phosphorylated Ca(2)E1P intermediate, but the rate of the energy-transducing conformational transition to E2P was reduced by >80%. Insertion of a smaller number of residues gave effects gradually increasing with the length of the insertion. Deletion of two residues at the same site, but not replacement with glycine, gave a similar reduction as the longest insertion. Insertion of one or three residues in another part of the A-M3 linker that forms an alpha-helix ("A3 helix") in E2/E2P conformations had even more profound effects on the ability of the enzyme to form E2P. These results demonstrate the importance of the length of the A-M3 linker and of the position and integrity of the A3 helix for stabilization of E2P and suggest that, during the normal enzyme cycle, strain of the A-M3 linker could contribute to destabilize the Ca(2)E1P state and thereby to drive the transition to E2P.
Collapse
Affiliation(s)
- Anne Nyholm Holdensen
- Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, Department of Physiology and Biophysics, Aarhus University, DK-8000 Aarhus C, Denmark
| | | |
Collapse
|
27
|
MacFarlane PM, Satriotomo I, Windelborn JA, Mitchell GS. NADPH oxidase activity is necessary for acute intermittent hypoxia-induced phrenic long-term facilitation. J Physiol 2009; 587:1931-42. [PMID: 19237427 DOI: 10.1113/jphysiol.2008.165597] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Phrenic long-term facilitation (pLTF) following acute intermittent hypoxia (AIH) is a form of spinal, serotonin-dependent synaptic plasticity that requires reactive oxygen species (ROS) formation. We tested the hypothesis that spinal NADPH oxidase activity is a necessary source of ROS for pLTF. Sixty minutes post-AIH (three 5-min episodes of 11% O(2), 5 min intervals), integrated phrenic and hypoglossal (XII) nerve burst amplitudes were increased from baseline, indicative of phrenic and XII LTF. Intrathecal injections (approximately C(4)) of apocynin or diphenyleneiodonium chloride (DPI), two structurally and functionally distinct inhibitors of the NADPH oxidase complex, attenuated phrenic, but not XII, LTF. Immunoblots from soluble (cytosolic) and particulate (membrane) fractions of ventral C(4) spinal segments revealed predominantly membrane localization of the NADPH oxidase catalytic subunit, gp91(phox), whereas membrane and cytosolic expression were both observed for the regulatory subunits, p47(phox) and RAC1. Immunohistochemical analysis of fixed tissues revealed these same subunits in presumptive phrenic motoneurons of the C(4) ventral horn, but not in neighbouring astrocytes or microglia. Collectively, these data demonstrate that NADPH oxidase subunits localized within presumptive phrenic motoneurons are a major source of ROS necessary for AIH-induced pLTF. Thus, NADPH oxidase activity is a key regulator of spinal synaptic plasticity, and may be a useful pharmaceutical target in developing therapeutic strategies for respiratory insufficiency in patients with, for example, cervical spinal injury.
Collapse
Affiliation(s)
- P M MacFarlane
- Department of Comparative Biosciences, University of Wisconsin, Madison, WI 53706, USA
| | | | | | | |
Collapse
|