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Clarke RJ. Electrostatic switch mechanisms of membrane protein trafficking and regulation. Biophys Rev 2023; 15:1967-1985. [PMID: 38192346 PMCID: PMC10771482 DOI: 10.1007/s12551-023-01166-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 11/17/2023] [Indexed: 01/10/2024] Open
Abstract
Lipid-protein interactions are normally classified as either specific or general. Specific interactions refer to lipid binding to specific binding sites within a membrane protein, thereby modulating the protein's thermal stability or kinetics. General interactions refer to indirect effects whereby lipids affect membrane proteins by modulating the membrane's physical properties, e.g., its fluidity, thickness, or dipole potential. It is not widely recognized that there is a third distinct type of lipid-protein interaction. Intrinsically disordered N- or C-termini of membrane proteins can interact directly but nonspecifically with the surrounding membrane. Many peripheral membrane proteins are held to the cytoplasmic surface of the plasma membrane via a cooperative combination of two forces: hydrophobic anchoring and electrostatic attraction. An acyl chain, e.g., myristoyl, added post-translationally to one of the protein's termini inserts itself into the lipid matrix and helps hold peripheral membrane proteins onto the membrane. Electrostatic attraction occurs between positively charged basic amino acid residues (lysine and arginine) on one of the protein's terminal tails and negatively charged phospholipid head groups, such as phosphatidylserine. Phosphorylation of either serine or tyrosine residues on the terminal tails via regulatory protein kinases allows for an electrostatic switch mechanism to control trafficking of the protein. Kinase action reduces the positive charge on the protein's tail, weakening the electrostatic attraction and releasing the protein from the membrane. A similar mechanism regulates many integral membrane proteins, but here only electrostatic interactions are involved, and the electrostatic switch modulates protein activity by altering the stabilities of different protein conformational states.
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Affiliation(s)
- Ronald J. Clarke
- School of Chemistry, University of Sydney, Sydney, NSW 2006 Australia
- The University of Sydney Nano Institute, Sydney, NSW 2006 Australia
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2
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Lev B, Chennath M, Cranfield CG, Cornelius F, Allen TW, Clarke RJ. Involvement of the alpha-subunit N-terminus in the mechanism of the Na +,K +-ATPase. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119539. [PMID: 37479188 DOI: 10.1016/j.bbamcr.2023.119539] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 06/26/2023] [Accepted: 07/10/2023] [Indexed: 07/23/2023]
Abstract
Previous studies have shown that cytoplasmic K+ release and the associated E2 → E1 conformational change of the Na+,K+-ATPase is a major rate-determining step of the enzyme's ion pumping cycle and hence a prime site of acute regulatory intervention. From the ionic strength dependence of the enzyme's distribution between the E2 and E1 states, it has also been found that E2 is stabilized by an electrostatic attraction. Any disruption of this electrostatic attraction would, thus, have profound effects on the rate of ion pumping. The aim of this paper is to identify the location of this interaction. Using enhanced-sampling molecular dynamics simulations with a predicted N-terminal structure added to the X-ray crystal structure of the Na+,K+-ATPase, a previously postulated salt bridge between Lys32 and Glu233 (rat sequence numbering) of the enzyme's α-subunit can be excluded. The residues never approach closely enough to form a salt bridge. In contrast, strong interactions with anionic lipid head groups were seen. To investigate the possibility of a protein-lipid interaction experimentally, the surface charge density of Na+,K+-ATPase-containing membrane fragments was estimated from zeta potential measurements to be 0.019 (± 0.001) C m-2. This is in good agreement with the charge density previously determined to be responsible for stabilization of the E2 state of 0.023 (± 0.009) C m-2 and the membrane charge density estimated here from published electron-microscopic images of 0.018C m-2. The results are, therefore, consistent with an interaction of the Na+,K+-ATPase α-subunit N-terminus with negatively-charged lipid head groups of the neighbouring cytoplasmic membrane surface as the origin of the electrostatic interaction stabilising the E2 state.
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Affiliation(s)
- B Lev
- School of Science, RMIT University, Melbourne, Vic, 3001, Australia
| | - M Chennath
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - C G Cranfield
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - F Cornelius
- Department of Biomedicine, University of Aarhus, DK-8000 Aarhus, C, Denmark
| | - T W Allen
- School of Science, RMIT University, Melbourne, Vic, 3001, Australia
| | - R J Clarke
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia; The University of Sydney Nano Institute, Sydney, NSW 2006, Australia.
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Funk RHW, Scholkmann F. The significance of bioelectricity on all levels of organization of an organism. Part 1: From the subcellular level to cells. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2023; 177:185-201. [PMID: 36481271 DOI: 10.1016/j.pbiomolbio.2022.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 11/24/2022] [Accepted: 12/03/2022] [Indexed: 12/12/2022]
Abstract
Bioelectricity plays an essential role in the structural and functional organization of biological organisms. In this first article of our three-part series, we summarize the importance of bioelectricity for the basic structural level of biological organization, i.e. from the subcellular level (charges, ion channels, molecules and cell organelles) to cells.
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Affiliation(s)
- Richard H W Funk
- Institute of Anatomy, Center for Theoretical Medicine, TU-Dresden, 01307, Dresden, Germany; Dresden International University, 01067, Dresden, Germany.
| | - Felix Scholkmann
- Biomedical Optics Research Laboratory, Department of Neonatology, University Hospital Zurich, University of Zurich, 8091, Zurich, Switzerland.
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Hossain KR, Clayton D, Goodchild SC, Rodger A, Payne RJ, Cornelius F, Clarke RJ. Order-disorder transitions of cytoplasmic N-termini in the mechanisms of P-type ATPases. Faraday Discuss 2021; 232:172-187. [PMID: 34549220 DOI: 10.1039/d0fd00040j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Membrane protein structure and function are modulated via interactions with their lipid environment. This is particularly true for integral membrane pumps, the P-type ATPases. These ATPases play vital roles in cell physiology, where they are associated with the transport of cations and lipids, thereby generating and maintaining crucial (electro-)chemical potential gradients across the membrane. Several pumps (Na+, K+-ATPase, H+, K+-ATPase and the plasma membrane Ca2+-ATPase) which are located in the asymmetric animal plasma membrane have been found to possess polybasic (lysine-rich) domains on their cytoplasmic surfaces, which are thought to act as phosphatidylserine (PS) binding domains. In contrast, the sarcoplasmic reticulum Ca2+-ATPase, located within an intracellular organelle membrane, does not possess such a domain. Here we focus on the lysine-rich N-termini of the plasma-membrane-bound Na+, K+- and H+, K+-ATPases. Synthetic peptides corresponding to the N-termini of these proteins were found, via quartz crystal microbalance and circular dichroism measurements, to interact via an electrostatic interaction with PS-containing membranes, thereby undergoing an increase in helical or other secondary structure content. As well as influencing ion pumping activity, it is proposed that this interaction could provide a mechanism for sensing the lipid asymmetry of the plasma membrane, which changes drastically when a cell undergoes apoptosis, i.e. programmed cell death. Thus, polybasic regions of plasma membrane-bound ion pumps could potentially perform the function of a "death sensor", signalling to a cell to reduce pumping activity and save energy.
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Affiliation(s)
| | - Daniel Clayton
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia.
| | - Sophia C Goodchild
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Alison Rodger
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Richard J Payne
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia.
| | - Flemming Cornelius
- Department of Biomedicine, University of Aarhus, DK-8000 Aarhus C, Denmark
| | - Ronald J Clarke
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia. .,The University of Sydney Nano Institute, Sydney, NSW 2006, Australia
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Dubey V, Stokes DL, Pedersen BP, Khandelia H. An Intracellular Pathway Controlled by the N-terminus of the Pump Subunit Inhibits the Bacterial KdpFABC Ion Pump in High K + Conditions. J Mol Biol 2021; 433:167008. [PMID: 33951450 DOI: 10.1016/j.jmb.2021.167008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 04/19/2021] [Accepted: 04/19/2021] [Indexed: 12/01/2022]
Abstract
The heterotetrameric bacterial KdpFABC transmembrane protein complex is an ion channel-pump hybrid that consumes ATP to import K+ against its transmembrane chemical potential gradient in low external K+ environments. The KdpB ion-pump subunit of KdpFABC is a P-type ATPase, and catalyses ATP hydrolysis. Under high external K+ conditions, K+ can diffuse into the cells through passive ion channels. KdpFABC must therefore be inhibited in high K+ conditions to conserve cellular ATP. Inhibition is thought to occur via unusual phosphorylation of residue Ser162 of the TGES motif of the cytoplasmic A domain. It is proposed that phosphorylation most likely traps KdpB in an inactive E1-P like conformation, but the molecular mechanism of phosphorylation-mediated inhibition remains unknown. Here, we employ molecular dynamics (MD) simulations of the dephosphorylated and phosphorylated versions of KdpFABC to demonstrate that phosphorylated KdpB is trapped in a conformation where the ion-binding site is hydrated by an intracellular pathway between transmembrane helices M1 and M2 which opens in response to the rearrangement of cytoplasmic domains resulting from phosphorylation. Cytoplasmic access of water to the ion-binding site is accompanied by a remarkable loss of secondary structure of the KdpB N-terminus and disruption of a key salt bridge between Glu87 in the A domain and Arg212 in the P domain. Our results provide the molecular basis of a unique mechanism of regulation amongst P-type ATPases, and suggest that the N-terminus has a significant role to play in the conformational cycle and regulation of KdpFABC.
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Affiliation(s)
- Vikas Dubey
- PHYLIFE: Physical Life Science, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, Odense 5230 M, Denmark
| | - David L Stokes
- Skirball Institute, Dept. of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
| | | | - Himanshu Khandelia
- PHYLIFE: Physical Life Science, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, Odense 5230 M, Denmark.
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6
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Osmotic and ionic regulation, and modulation by protein kinases, FXYD2 peptide and ATP of gill (Na+, K+)-ATPase activity, in the swamp ghost crab Ucides cordatus (Brachyura, Ocypodidae). Comp Biochem Physiol B Biochem Mol Biol 2020; 250:110507. [DOI: 10.1016/j.cbpb.2020.110507] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 09/08/2020] [Accepted: 09/14/2020] [Indexed: 11/20/2022]
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Clarke R, Hossain K, Cao K. Physiological roles of transverse lipid asymmetry of animal membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183382. [DOI: 10.1016/j.bbamem.2020.183382] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 06/01/2020] [Accepted: 06/02/2020] [Indexed: 02/07/2023]
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8
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Faraj SE, Valsecchi WM, Cerf NT, Fedosova NU, Rossi RC, Montes MR. The interaction of Na +, K +, and phosphate with the gastric H,K-ATPase. Kinetics of E1-E2 conformational changes assessed by eosin fluorescence measurements. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1863:183477. [PMID: 32949561 DOI: 10.1016/j.bbamem.2020.183477] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 09/10/2020] [Accepted: 09/11/2020] [Indexed: 12/12/2022]
Abstract
H,K-ATPase and Na,K-ATPase show the highest degree of sequence similarity among all other members of the P-type ATPases family. To explore their common features in terms of ligand binding, we evaluated conformational transitions due to the binding of Na+, K+ and Pi in the H,K-ATPase, and compared the results with those obtained for the Na,K-ATPase. This work shows that eosin fluorescence time courses provide a reasonably precise method to study the kinetics of the E1-E2 conformational changes in the H,K-ATPase. We found that, although Na+ shifts the equilibrium toward the E1 conformation and seems to compete with H+ in ATPase activity assays, it was neither possible to isolate a Na+-occluded state, nor to reveal an influx of Na+ related to H,K-ATPase activity. The high rate of the E2K → E1 transition found for the H,K-ATPase, which is not compatible with the presence of a K+-occluded form, agrees with the negligible level of occluded Rb+ (used as a K+ congener) found in the absence of added ligands. The use of vanadate and fluorinated metals to induce E2P-like states increased the level of occluded Rb+ and suggests that-during dephosphorylation-the probability of K+ to remain occluded increases from the E2P-ground to the E2P-product state. From kinetic experiments we found an unexpected increase in the values of kobs for E2P formation with [Pi]; consequently, to obey the Albers-Post model, the binding of Pi to the E2 state cannot be a rapid-equilibrium reaction.
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Affiliation(s)
- S E Faraj
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas "Prof. Alejandro C. Paladini" (IQUIFIB), Buenos Aires, Argentina
| | - W M Valsecchi
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas "Prof. Alejandro C. Paladini" (IQUIFIB), Buenos Aires, Argentina
| | - N T Cerf
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas "Prof. Alejandro C. Paladini" (IQUIFIB), Buenos Aires, Argentina
| | - N U Fedosova
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - R C Rossi
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas "Prof. Alejandro C. Paladini" (IQUIFIB), Buenos Aires, Argentina
| | - M R Montes
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas "Prof. Alejandro C. Paladini" (IQUIFIB), Buenos Aires, Argentina.
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Moraes CM, Lucena MN, Garçon DP, Pinto MR, Fabri LM, Faleiros RO, Fontes CFL, McNamara JC, Leone FA. Biochemical Characterization and Allosteric Modulation by Magnesium of (Na +, K +)-ATPase Activity in the Gills of the Red Mangrove Crab Goniopsis cruentata (Brachyura, Grapsidae). J Membr Biol 2020; 253:229-245. [PMID: 32440867 DOI: 10.1007/s00232-020-00120-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 05/02/2020] [Indexed: 11/26/2022]
Abstract
We provide a kinetic characterization of (Na+, K+)-ATPase activity in a posterior gill microsomal fraction from the grapsid crab Goniopsis cruentata. (Na+, K+)-ATPase activity constitutes 95% of total ATPase activity, and sucrose density centrifugation reveals an ATPase activity peak between 25 and 35% sucrose, distributed into two, partially separated protein fractions. The (Na+, K+)-ATPase α-subunit is localized throughout the ionocyte cytoplasm and has an Mr of ≈ 10 kDa and hydrolyzes ATP obeying cooperative kinetics. Low (VM = 186.0 ± 9.3 nmol Pi min-1 mg-1 protein and K0.5 = 0.085 ± 0.004 mmol L-1) and high (VM = 153.4 ± 7.7 nmol Pi min-1 mg-1 protein and K0.5 = 0.013 ± 0.0006 mmol L-1) affinity ATP binding sites were characterized. At low ATP concentrations, excess Mg2+ stimulates the enzyme, triggering exposure of a high-affinity binding site that accounts for 50% of (Na+, K+)-ATPase activity. Stimulation by Mg2+ (VM = 425.9 ± 25.5 nmol Pi min-1 mg-1 protein, K0.5 = 0.16 ± 0.01 mmol L-1), K+ (VM = 485.3 ± 24.3 nmol Pi min-1 mg-1 protein, K0.5 = 0.9 ± 0.05 mmol L-1), Na+ (VM = 425.0 ± 23.4 nmol Pi min-1 mg-1 protein, K0.5 = 5.1 ± 0.3 mmol L-1) and NH4+ (VM = 497.9 ± 24.9 nmol Pi min-1 mg-1 protein, K0.5 = 9.7 ± 0.5 mmol L-1) obeys cooperative kinetics. Ouabain inhibits up to 95% of ATPase activity with KI = 196.6 ± 9.8 µmol L-1. This first kinetic characterization of the gill (Na+, K+)-ATPase in Goniopsis cruentata enables better comprehension of the biochemical underpinnings of osmoregulatory ability in this semi-terrestrial mangrove crab.
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Affiliation(s)
- Cintya M Moraes
- Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes 3900, Ribeirão Preto, SP, 14040-901, Brazil
| | - Malson N Lucena
- Instituto de Biociências, Universidade Federal do Mato Grosso do Sul, Campo Grande, MS, Brazil
| | | | - Marcelo R Pinto
- Laboratório de Biopatologia e Biologia Molecular Universidade Uberaba, Uberaba, MG, Brazil
| | - Leonardo M Fabri
- Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes 3900, Ribeirão Preto, SP, 14040-901, Brazil
| | - Rogério O Faleiros
- Departamento de Ciências Agrárias e Biológicas, Universidade Federal do Espírito Santo, São Mateus, ES, Brazil
| | - Carlos F L Fontes
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - John C McNamara
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
- Centro de Biologia Marinha, Universidade de São Paulo, São Sebastião, SP, Brazil
| | - Francisco A Leone
- Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes 3900, Ribeirão Preto, SP, 14040-901, Brazil.
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Zhou X, Qian H, Zhang D, Zeng L. Inhibition of autophagy of Cajal mesenchymal cells by gavage of tong bian decoction based on the rat model of chronic transit constipation. Saudi J Biol Sci 2019; 27:623-628. [PMID: 32210680 PMCID: PMC6997910 DOI: 10.1016/j.sjbs.2019.11.040] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 11/16/2019] [Accepted: 11/27/2019] [Indexed: 01/30/2023] Open
Abstract
The objective of this research was to study the effect of tong bian decoction on colon transport function of interstitial cells of Cajal (ICC) in chronic transit constipation (CTC) and the inhibition of autophagy of ICC, so as to achieve the free movement of the bowels. In this research, the experimental rats were divided into normal group (NG) and model group (MG) by random method, and the rat model of CTC was constructed by subdivision circulatory increasing operation gavage method of rhubarb. After the successful establishment of the model, the rats were divided into normal group, MG, tong bian decoction gavage group, mosapride group and normal recovery group. Then, rats in the NG and the MG were killed at the same time, and rats in the tong bian decoction gavage group, mosapride group and normal recovery group were killed at the same time. In this study, the transport function of colon of rats in each group was detected by activated carbon method, and the number of fecal residues in the colon was observed. The mRNA expression of c-kit gene in intestinal tissue of rat was detected by real-time quantitative polymerase chain reaction (RT-qPCR). In addition, the changes of ICC in rats treated with different drugs were detected by immunohistochemical method. The results revealed that in the tong bian decoction gavage group, the water content in the feces of rats was remarkably increased (P < 0.05), the amount of residual feces in the colon was remarkably reduced (P < 0.01), the percentage of carbon powder propulsion in small intestine was remarkably increased (P < 0.01), the staining area of ICC positive cells in colon tissue was remarkably increased (P < 0.05), and the expression of c-kit mRNA was remarkably increased (P < 0.01). It can be concluded that the tong bian decoction could effectively enhance the colon transport function in the rat model of CTC. This laxative mechanism promotes the regeneration and repair ability of ICC by inhibiting the autophagy of ICC, and provides power for the large intestine, so as to achieve the free movement of the bowels. Therefore, the results of this study have certain guiding meaning for the treatment of CTC with traditional Chinese medicine.
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Affiliation(s)
- Xi Zhou
- Department of Anorectal Surgery, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Haihua Qian
- Department of Anorectal Surgery, Affiliated Hospital of Nanjing University of Chinese Medicine, Jiangsu Province Hospital of Chinese Medicine, Nanjing 210023, China
| | - Dan Zhang
- Department of Anorectal Surgery, Affiliated Hospital of Nanjing University of Chinese Medicine, Jiangsu Province Hospital of Chinese Medicine, Nanjing 210023, China
| | - Li Zeng
- Department of Anorectal Surgery, Nanjing University of Chinese Medicine, Nanjing 210023, China
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11
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Hossain KR, Li X, Zhang T, Paula S, Cornelius F, Clarke RJ. Polarity of the ATP binding site of the Na +,K +-ATPase, gastric H +,K +-ATPase and sarcoplasmic reticulum Ca 2+-ATPase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183138. [PMID: 31790695 DOI: 10.1016/j.bbamem.2019.183138] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 11/15/2019] [Accepted: 11/27/2019] [Indexed: 11/18/2022]
Abstract
A fluorescence ratiometric method utilizing the probe eosin Y is presented for estimating the ATP binding site polarity of P-type ATPases in different conformational states. The method has been calibrated by measurements in a series of alcohols and tested using complexation of eosin Y with methyl-β-cyclodextrin. The results obtained with the Na+,K+-, H+,K+- and sarcoplasmic reticulum Ca2+-ATPases indicate that the ATP binding site, to which eosin is known to bind, is significantly more polar in the case of the Na+,K+- and H+,K+-ATPases compared to the Ca2+-ATPase. This result was found to be consistent with docking calculations of eosin with the E2 conformational state of the Na+,K+-ATPase and the Ca2+-ATPase. Fluorescence experiments showed that eosin binds significantly more strongly to the E1 conformation of the Na+,K+-ATPase than the E2 conformation, but in the case of the Ca2+-ATPase both fluorescence experiments and docking calculations showed no significant difference in binding affinity between the two conformations. This result could be due to the fact that, in contrast to the Na+,K+- and H+,K+-ATPases, the E2-E1 transition of the Ca2+-ATPase does not involve the movement of a lysine-rich N-terminal tail which may affect the overall enzyme conformation. Consistent with this hypothesis, the eosin affinity of the E1 conformation of the Na+,K+-ATPase was significantly reduced after N-terminal truncation. It is suggested that changes in conformational entropy of the N-terminal tail of the Na+, K+- and the H+,K+-ATPases during the E2-E1 transition could affect the thermodynamic stability of the E1 conformation and hence its ATP binding affinity.
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Affiliation(s)
- K R Hossain
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
| | - X Li
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
| | - T Zhang
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - S Paula
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - F Cornelius
- Department of Biomedicine, University of Aarhus, DK-8000 Aarhus C, Denmark
| | - R J Clarke
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia; The University of Sydney Nano Institute, Sydney, NSW 2006, Australia.
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12
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Gorman A, Hossain KR, Cornelius F, Clarke RJ. Penetration of phospholipid membranes by poly-l-lysine depends on cholesterol and phospholipid composition. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183128. [PMID: 31734310 DOI: 10.1016/j.bbamem.2019.183128] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 10/28/2019] [Accepted: 11/08/2019] [Indexed: 10/25/2022]
Abstract
Clusters of positively-charged basic amino acid residues, particularly lysine, are known to promote the interaction of many peripheral membrane proteins with the cytoplasmic surface of the plasma membrane via electrostatic interactions. In this work, cholesterol's effects on the interaction between lysine residues and membranes have been studied. Using poly-l-lysine (PLL) and vesicles as models to mimic the interaction between lysine-rich protein domains and the plasma membrane, light scattering measurements indicated cholesterol enhanced the electrostatic interaction through indirectly affecting the negatively charged phospholipid dioleoylphosphatidylserine, DOPS. Addition of PLL to lipid vesicles containing DOPS showed an initial increase in static light scattering (SLS), attributed to binding of PLL to the vesicle surface, followed by a slower continuously declining SLS signal, which, from comparison with fluorescent dye leakage studies could be attributed to vesicle lysis. Although electrostatic interactions between PLL and the membrane were not necessary for penetration to occur, cholesterol promoted membrane disruption of negatively charged vesicles, possibly by increasing the electrostatic interactions between PLL and the membrane. In contrast, cholesterol lowered the susceptibility of uncharged vesicles (formed using dioleoylphosphatidylcholine, DOPC) to PLL penetration. This can be explained by the absence of electrostatic interactions and cholesterol's known ability to increase membrane thickness and mechanical strength. Thus, the ability of cationic peptides to penetrate membranes including cholesterol is likely to depend on the membrane's PS:PC ratio.
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Affiliation(s)
- Amy Gorman
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia; Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | | | - Flemming Cornelius
- Department of Biomedicine, University of Aarhus, DK-8000 Aarhus C, Denmark
| | - Ronald J Clarke
- School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia; The University of Sydney Nano Institute, Sydney, NSW 2006, Australia.
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Garcia A, Lev B, Hossain KR, Gorman A, Diaz D, Pham THN, Cornelius F, Allen TW, Clarke RJ. Cholesterol depletion inhibits Na +,K +-ATPase activity in a near-native membrane environment. J Biol Chem 2019; 294:5956-5969. [PMID: 30770471 PMCID: PMC6463725 DOI: 10.1074/jbc.ra118.006223] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 02/08/2019] [Indexed: 12/28/2022] Open
Abstract
Cholesterol's effects on Na+,K+-ATPase reconstituted in phospholipid vesicles have been extensively studied. However, previous studies have reported both cholesterol-mediated stimulation and inhibition of Na+,K+-ATPase activity. Here, using partial reaction kinetics determined via stopped-flow experiments, we studied cholesterol's effect on Na+,K+-ATPase in a near-native environment in which purified membrane fragments were depleted of cholesterol with methyl-β-cyclodextrin (mβCD). The mβCD-treated Na+,K+-ATPase had significantly reduced overall activity and exhibited decreased observed rate constants for ATP phosphorylation (ENa3+ → E2P, i.e. phosphorylation by ATP and Na+ occlusion from the cytoplasm) and K+ deocclusion with subsequent intracellular Na+ binding (E2K2+ → E1Na3+). However, cholesterol depletion did not affect the observed rate constant for K+ occlusion by phosphorylated Na+,K+-ATPase on the extracellular face and subsequent dephosphorylation (E2P → E2K2+). Thus, partial reactions involving cation binding and release at the protein's intracellular side were most dependent on cholesterol. Fluorescence measurements with the probe eosin indicated that cholesterol depletion stabilizes the unphosphorylated E2 state relative to E1, and the cholesterol depletion-induced slowing of ATP phosphorylation kinetics was consistent with partial conversion of Na+,K+-ATPase into the E2 state, requiring a slow E2 → E1 transition before the phosphorylation. Molecular dynamics simulations of Na+,K+-ATPase in membranes with 40 mol % cholesterol revealed cholesterol interaction sites that differ markedly among protein conformations. They further indicated state-dependent effects on membrane shape, with the E2 state being likely disfavored in cholesterol-rich bilayers relative to the E1P state because of a greater hydrophobic mismatch. In summary, cholesterol extraction from membranes significantly decreases Na+,K+-ATPase steady-state activity.
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Affiliation(s)
- Alvaro Garcia
- From the School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia; The University of Sydney Nano Institute, Sydney, NSW 2006, Australia
| | - Bogdan Lev
- the School of Science, RMIT University, Melbourne, VIC 3001, Australia
| | - Khondker R Hossain
- From the School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
| | - Amy Gorman
- From the School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia; the Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Dil Diaz
- From the School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
| | | | - Flemming Cornelius
- the Department of Biomedicine, University of Aarhus, DK-8000 Aarhus C, Denmark
| | - Toby W Allen
- the School of Science, RMIT University, Melbourne, VIC 3001, Australia; the Department of Chemistry, University of California, Davis, California 95616
| | - Ronald J Clarke
- From the School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia; The University of Sydney Nano Institute, Sydney, NSW 2006, Australia.
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Corradi V, Sejdiu BI, Mesa-Galloso H, Abdizadeh H, Noskov SY, Marrink SJ, Tieleman DP. Emerging Diversity in Lipid-Protein Interactions. Chem Rev 2019; 119:5775-5848. [PMID: 30758191 PMCID: PMC6509647 DOI: 10.1021/acs.chemrev.8b00451] [Citation(s) in RCA: 245] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
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Membrane
lipids interact with proteins in a variety of ways, ranging
from providing a stable membrane environment for proteins to being
embedded in to detailed roles in complicated and well-regulated protein
functions. Experimental and computational advances are converging
in a rapidly expanding research area of lipid–protein interactions.
Experimentally, the database of high-resolution membrane protein structures
is growing, as are capabilities to identify the complex lipid composition
of different membranes, to probe the challenging time and length scales
of lipid–protein interactions, and to link lipid–protein
interactions to protein function in a variety of proteins. Computationally,
more accurate membrane models and more powerful computers now enable
a detailed look at lipid–protein interactions and increasing
overlap with experimental observations for validation and joint interpretation
of simulation and experiment. Here we review papers that use computational
approaches to study detailed lipid–protein interactions, together
with brief experimental and physiological contexts, aiming at comprehensive
coverage of simulation papers in the last five years. Overall, a complex
picture of lipid–protein interactions emerges, through a range
of mechanisms including modulation of the physical properties of the
lipid environment, detailed chemical interactions between lipids and
proteins, and key functional roles of very specific lipids binding
to well-defined binding sites on proteins. Computationally, despite
important limitations, molecular dynamics simulations with current
computer power and theoretical models are now in an excellent position
to answer detailed questions about lipid–protein interactions.
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Affiliation(s)
- Valentina Corradi
- Centre for Molecular Simulation and Department of Biological Sciences , University of Calgary , 2500 University Drive NW , Calgary , Alberta T2N 1N4 , Canada
| | - Besian I Sejdiu
- Centre for Molecular Simulation and Department of Biological Sciences , University of Calgary , 2500 University Drive NW , Calgary , Alberta T2N 1N4 , Canada
| | - Haydee Mesa-Galloso
- Centre for Molecular Simulation and Department of Biological Sciences , University of Calgary , 2500 University Drive NW , Calgary , Alberta T2N 1N4 , Canada
| | - Haleh Abdizadeh
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 7 , 9747 AG Groningen , The Netherlands
| | - Sergei Yu Noskov
- Centre for Molecular Simulation and Department of Biological Sciences , University of Calgary , 2500 University Drive NW , Calgary , Alberta T2N 1N4 , Canada
| | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 7 , 9747 AG Groningen , The Netherlands
| | - D Peter Tieleman
- Centre for Molecular Simulation and Department of Biological Sciences , University of Calgary , 2500 University Drive NW , Calgary , Alberta T2N 1N4 , Canada
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Effect of Cholesterol on the Dipole Potential of Lipid Membranes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1115:135-154. [DOI: 10.1007/978-3-030-04278-3_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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16
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Diaz D, Clarke RJ. Evolutionary Analysis of the Lysine-Rich N-terminal Cytoplasmic Domains of the Gastric H +,K +-ATPase and the Na +,K +-ATPase. J Membr Biol 2018; 251:653-666. [PMID: 30056551 DOI: 10.1007/s00232-018-0043-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 07/19/2018] [Indexed: 12/16/2022]
Abstract
The catalytic α-subunits of both the Na+,K+-ATPase and the gastric H+,K+-ATPase possess lysine-rich N-termini which project into the cytoplasm. Due to conflicting experimental results, it is currently unclear whether the N-termini play a role in ion pump function or regulation, and, if they do, by what mechanism. Comparison of the lysine frequencies of the N-termini of both proteins with those of all of their extramembrane domains showed that the N-terminal lysine frequencies are far higher than one would expect simply from exposure to the aqueous solvent. The lysine frequency was found to vary significantly between different vertebrate classes, but this is due predominantly to a change in N-terminal length. As evidenced by a comparison between fish and mammals, an evolutionary trend towards an increase of the length of the N-terminus of the H+,K+-ATPase on going from an ancestral fish to mammals could be identified. This evolutionary trend supports the hypothesis that the N-terminus is important in ion pump function or regulation. In placental mammals, one of the lysines is replaced by serine (Ser-27), which is a target for protein kinase C. In most other animal species, a lysine occupies this position and hence no protein kinase C target is present. Interaction with protein kinase C is thus not the primary role of the lysine-rich N-terminus. The disordered structure of the N-terminus may, via increased flexibility, facilitate interaction with another binding partner, e.g. the surrounding membrane, or help to stabilise particular enzyme conformations via the increased entropy it produces.
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Affiliation(s)
- Dil Diaz
- School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia
| | - Ronald J Clarke
- School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia. .,The University of Sydney Nano Institute, Sydney, NSW, 2006, Australia.
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Interaction of N-terminal peptide analogues of the Na+,K+-ATPase with membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018. [DOI: 10.1016/j.bbamem.2018.03.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Disruption of Ankyrin B and Caveolin-1 Interaction Sites Alters Na +,K +-ATPase Membrane Diffusion. Biophys J 2017; 113:2249-2260. [PMID: 28988699 DOI: 10.1016/j.bpj.2017.08.053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 07/21/2017] [Accepted: 08/14/2017] [Indexed: 02/07/2023] Open
Abstract
The Na+,K+-ATPase is a plasma membrane ion transporter of high physiological importance for ion homeostasis and cellular excitability in electrically active tissues. Mutations in the genes coding for Na+,K+-ATPase α-subunit isoforms lead to severe human pathologies including Familial Hemiplegic Migraine type 2, Alternating Hemiplegia of Childhood, Rapid-onset Dystonia Parkinsonism, or epilepsy. Many of the reported mutations lead to change- or loss-of-function effects, whereas others do not alter the functional properties, but lead to, e.g., reduced protein stability, reduced protein expression, or defective plasma membrane targeting. Na+,K+-ATPase frequently assembles with other membrane transporters or cellular matrix proteins in specialized plasma membrane microdomains, but the effects of these interactions on targeting or protein mobility are elusive so far. Mutation of established interaction motifs of the Na+,K+-ATPase with ankyrin B and caveolin-1 are expected to result in changes in plasma membrane targeting, changes of the localization pattern, and of the diffusion behavior of the enzyme. We studied the consequences of mutations in these binding sites by monitoring diffusion of eGFP-labeled Na+,K+-ATPase constructs in the plasma membrane of HEK293T cells by fluorescence correlation spectroscopy as well as fluorescence recovery after photobleaching or photoswitching, and observed significant differences compared to the wild-type enzyme, with synergistic effects for combinations of interaction site mutations. These measurements expand the possibilities to study the consequences of Na+,K+-ATPase mutations and provide information about the interaction of Na+,K+-ATPase α-isoforms with cellular matrix proteins, the cytoskeleton, or other membrane protein complexes.
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