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Chowdhury SR, Jaiswal S, Lu HP. Compressive-force induced activation of apo-calmodulin in protein signalling. Phys Chem Chem Phys 2020; 22:1092-1096. [PMID: 31894209 DOI: 10.1039/c9cp05074d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Mechanical force plays a critical role in the relationship between protein structure and function. Force manipulation by Atomic Force Microscope can be significant and trigger chemical and biological activities of proteins. Previously we have reported that Apo-CaM undergoes through a spontaneous tertiary structural rupture under a piconewton compressive force. Here we have observed that the ruptured Apo-CaM molecules can be available to bind with C28W peptide, a typical protein signalling activity that only a Ca2+-activated CaM has. This behaviour is both unexpected and profound, as CaM in its Ca2+-non-activated form has a closed structure which does not presumably allow the molecule to bind to target peptides. In this experiment, we demonstrate that both chemical activation and force activation can play a vital role in biology, such as the cell-signalling protein dynamics and function.
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Affiliation(s)
- Susovan Roy Chowdhury
- Department of Chemistry, Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA.
| | - Sunidhi Jaiswal
- Department of Chemistry, Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA.
| | - H Peter Lu
- Department of Chemistry, Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA.
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2
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Jiang G, Wu F, Li Z, Li T, Gupta VK, Duan X, Jiang Y. Sulfoxidation Regulation of Musa acuminata Calmodulin (MaCaM) Influences the Functions of MaCaM-Binding Proteins. PLANT & CELL PHYSIOLOGY 2018; 59:1214-1224. [PMID: 29566226 DOI: 10.1093/pcp/pcy057] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 03/19/2018] [Indexed: 05/25/2023]
Abstract
Sulfoxidation of methionine in proteins by reactive oxygen species can cause conformational alteration or functional impairment, and can be reversed by methionine sulfoxide reductase (Msr). Currently, only a few potential Msr substrates have been confirmed in higher plants. Here, we investigated Msr-mediated sulfoxidation regulation of calmodulin (CaM) and its underlying biological significance in relation to banana fruit ripening and senescence. Expression of MaCaM1 and MaMsrA7 was up-regulated with increased ripening and senescence. We verified that MaCaM1 interacts with MaMsrA7 in vitro and in vivo, and sulfoxidated MaCaM1 could be partly repaired by MaMsrA7 (MaMsrA7 reduces oxidized residues Met77 and Met110 in MaCaM1). Furthermore, we investigated two known CaM-binding proteins, catalase (MaCAT1) and MaHY5-1. MaHY5-1 acts as a transcriptional repressor of carotenoid biosynthesis-related genes (MaPSY1, MaPSY2 and MaPSY3) in banana fruit. MaCaM1 could enhance the catalytic activity of MaCAT1 and the transcriptional repression activity of MaHY5-1 toward MaPSY2. Mimicked sulfoxidation in MaCaM1 did not affect the physical interactions of the protein with MaHY5-1 and MaCAT1, but reduced the catalytic activity of MaCAT1 and the transcriptional repression activity of MaHY5-1. Our data suggest that sulfoxidation modification in MaCaM1 by MaMsrA7 regulates antioxidant response and gene transcription, thereby being involved in regulation of ripening and senescence of banana fruit.
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Affiliation(s)
- Guoxiang Jiang
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Fuwang Wu
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Zhiwei Li
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Taotao Li
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Vijai Kumar Gupta
- Department of Chemistry and Biotechnology, ERA Chair of Green Chemistry, School of Science, Tallinn University of Technology, Tallinn 12618, Estonia
| | - Xuewu Duan
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Yueming Jiang
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
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3
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Sadoine M, Cerminara M, Gerrits M, Fitter J, Katranidis A. Cotranslational Incorporation into Proteins of a Fluorophore Suitable for smFRET Studies. ACS Synth Biol 2018; 7:405-411. [PMID: 29370697 DOI: 10.1021/acssynbio.7b00433] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Single-molecule FRET (smFRET) is a powerful tool to investigate conformational changes of biological molecules. In general, smFRET studies require protein samples that are site-specifically double-labeled with a pair of donor and acceptor fluorophores. The common approaches to produce such samples cannot be applied when studying the synthesis and folding of the polypeptide chain on the ribosome. The best strategy is to incorporate two fluorescent amino acids cotranslationally using cell-free protein synthesis systems. Here, we demonstrate the cotranslational site-specific incorporation into a model protein of Atto633, a dye with excellent photophysical properties, suitable for single molecule spectroscopy, together with a second dye using a combination of the sense cysteine and the nonsense amber codon. In this work we show that cotranslational incorporation of good fluorophores into proteins is a viable strategy to produce suitable samples for smFRET studies.
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Affiliation(s)
- Mayuri Sadoine
- Forschungszentrum Jülich, Institute of Complex Systems
ICS-5, 52428 Jülich, Germany
| | - Michele Cerminara
- Forschungszentrum Jülich, Institute of Complex Systems
ICS-5, 52428 Jülich, Germany
| | - Michael Gerrits
- Biocatalysis
Group, Department of Chemistry, Technische Universität Berlin, 10623 Berlin, Germany
| | - Jörg Fitter
- Forschungszentrum Jülich, Institute of Complex Systems
ICS-5, 52428 Jülich, Germany
- RWTH Aachen University, I.Physikalisches
Institut (IA), 52062 Aachen, Germany
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4
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Sadoine M, Cerminara M, Kempf N, Gerrits M, Fitter J, Katranidis A. Selective Double-Labeling of Cell-Free Synthesized Proteins for More Accurate smFRET Studies. Anal Chem 2017; 89:11278-11285. [DOI: 10.1021/acs.analchem.7b01639] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mayuri Sadoine
- Forschungszentrum
Jülich, Institute of Complex Systems ICS-5, 52425 Jülich, Germany
| | - Michele Cerminara
- Forschungszentrum
Jülich, Institute of Complex Systems ICS-5, 52425 Jülich, Germany
| | - Noémie Kempf
- Forschungszentrum
Jülich, Institute of Complex Systems ICS-5, 52425 Jülich, Germany
| | | | - Jörg Fitter
- Forschungszentrum
Jülich, Institute of Complex Systems ICS-5, 52425 Jülich, Germany
- 1. Physikalisches
Institut (IA), RWTH Aachen, 52062 Aachen, Germany
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5
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Jiang G, Xiao L, Yan H, Zhang D, Wu F, Liu X, Su X, Dong X, Wang J, Duan X, Jiang Y. Redox regulation of methionine in calmodulin affects the activity levels of senescence-related transcription factors in litchi. Biochim Biophys Acta Gen Subj 2017; 1861:1140-1151. [PMID: 28188859 DOI: 10.1016/j.bbagen.2017.02.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Revised: 01/24/2017] [Accepted: 02/06/2017] [Indexed: 12/21/2022]
Abstract
Reactive oxygen species (ROS) play a role in aging and senescence in organisms. The oxidation of methionine (Met) residues in proteins to Met sulfoxide by ROS can cause conformational alteration and functional impairments. Met oxidation is reversed by Met sulfoxide reductase (Msr) A and B. Currently, the repair of oxidized proteins by Msr and Msr-mediated physiological functions are not well understood, especially in higher plants. The down-regulated expression of LcMsrA1/B1 may be involved in the senescence of litchi (Litchi chinensis) fruit. We verified that LcCaM1 is a substrate of LcMsrA1 and LcMsrB1 in vitro and in vivo, and oxidized LcCaM1 could be repaired by LcMsrA1 in combination with LcMsrB1. Moreover, LcMsrA1 and LcMsrB1 play important roles in repairing oxidized Met110 and Met125 residues, respectively, in LcCaM1. Furthermore, the Met oxidation in LcCaM1 did not affect its physical interactions with two LcCaM1-binding senescence-related transcription factors LcNAC13 and LcWRKY1, but enhanced their DNA-binding activities. Therefore, we hypothesized that the down-regulated expression of LcMsrA1/B1 results in the accelerated oxidation of LcCaM1, which enhanced the DNA-binding activities of LcNAC13 and LcWRKY1, thereby activating or repressing the expression of senescence-related genes.
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Affiliation(s)
- Guoxiang Jiang
- Guangdong Provincial Key Laboratory of Applied Botany/Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Lu Xiao
- Guangdong Provincial Key Laboratory of Applied Botany/Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Huiling Yan
- Guangdong Provincial Key Laboratory of Applied Botany/Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dandan Zhang
- Guangdong Provincial Key Laboratory of Applied Botany/Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Fuwang Wu
- Guangdong Provincial Key Laboratory of Applied Botany/Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Xuncheng Liu
- Guangdong Provincial Key Laboratory of Applied Botany/Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
| | - Xinguo Su
- Guangdong Food and Drug Vocational College, Guangzhou 510520, China
| | - Xinhong Dong
- College of Chemistry and Biology Engineering, Guilin University of Technology, Gulin 541004, China
| | - Jiasheng Wang
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA 30602, USA
| | - Xuewu Duan
- Guangdong Provincial Key Laboratory of Applied Botany/Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.
| | - Yueming Jiang
- Guangdong Provincial Key Laboratory of Applied Botany/Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
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6
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Khanmoradi M, Nikoorazm M, Ghorbani-Choghamarani A. Anchoring of Cu(II)-vanillin Schiff base complex on MCM-41: A highly efficient and recyclable catalyst for synthesis of sulfides and 5-substituted 1H
-tetrazoles and oxidation of sulfides to sulfoxides. Appl Organomet Chem 2017. [DOI: 10.1002/aoc.3693] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Maryam Khanmoradi
- Department of Chemistry, Faculty of Science; Ilam University; PO Box 69315516 Ilam Iran
| | - Mohsen Nikoorazm
- Department of Chemistry, Faculty of Science; Ilam University; PO Box 69315516 Ilam Iran
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Mary Imelda Jayaseeli A, Ramdass A, Rajagopal S. Selective H2O2 oxidation of organic sulfides to sulfoxides catalyzed by cobalt(III)–salen ion. Polyhedron 2015. [DOI: 10.1016/j.poly.2015.07.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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8
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Determination of the individual roles of the linker residues in the interdomain motions of calmodulin using NMR chemical shifts. J Mol Biol 2014; 426:1826-38. [PMID: 24530797 DOI: 10.1016/j.jmb.2014.02.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Revised: 01/18/2014] [Accepted: 02/04/2014] [Indexed: 12/22/2022]
Abstract
Many protein molecules are formed by two or more domains whose structures and dynamics are closely related to their biological functions. It is thus important to develop methods to determine the structural properties of these multidomain proteins. Here, we characterize the interdomain motions in the calcium-bound state of calmodulin (Ca(2+)-CaM) using NMR chemical shifts as replica-averaged structural restraints in molecular dynamics simulations. We find that the conformational fluctuations of the interdomain linker, which are largely responsible for the overall interdomain motions of CaM, can be well described by exploiting the information provided by chemical shifts. We thus identify 10 residues in the interdomain linker region that change their conformations upon substrate binding. Five of these residues (Met76, Lys77, Thr79, Asp80 and Ser81) are highly flexible and cover the range of conformations observed in the substrate-bound state, while the remaining five (Arg74, Lys75, Asp78, Glu82 and Glu83) are much more rigid and do not populate conformations typical of the substrate-bound form. The ensemble of conformations representing the Ca(2+)-CaM state obtained in this study is in good agreement with residual dipolar coupling, paramagnetic resonance enhancement, small-angle X-ray scattering and fluorescence resonance energy transfer measurements, which were not used as restraints in the calculations. These results provide initial evidence that chemical shifts can be used to characterize the conformational fluctuations of multidomain proteins.
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9
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Penniston JT, Caride AJ, Strehler EE. Alternative pathways for association and dissociation of the calmodulin-binding domain of plasma membrane Ca(2+)-ATPase isoform 4b (PMCA4b). J Biol Chem 2012; 287:29664-71. [PMID: 22767601 DOI: 10.1074/jbc.m112.377556] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The calmodulin (CaM)-binding domain of isoform 4b of the plasma membrane Ca(2+) -ATPase (PMCA) pump is represented by peptide C28. CaM binds to either PMCA or C28 by a mechanism in which the primary anchor residue Trp-1093 binds to the C-terminal lobe of the extended CaM molecule, followed by collapse of CaM with the N-terminal lobe binding to the secondary anchor Phe-1110 (Juranic, N., Atanasova, E., Filoteo, A. G., Macura, S., Prendergast, F. G., Penniston, J. T., and Strehler, E. E. (2010) J. Biol. Chem. 285, 4015-4024). This is a relatively rapid reaction, with an apparent half-time of ~1 s. The dissociation of CaM from PMCA4b or C28 is much slower, with an overall half-time of ~10 min. Using targeted molecular dynamics, we now show that dissociation of Ca(2+)-CaM from C28 may occur by a pathway in which Trp-1093, although deeply embedded in a pocket in the C-terminal lobe of CaM, leaves first. The dissociation begins by relatively rapid release of Trp-1093, followed by very slow release of Phe-1110, removal of C28, and return of CaM to its conformation in the free state. Fluorescence measurements and molecular dynamics calculations concur in showing that this alternative path of release of the PMCA4b CaM-binding domain is quite different from that of binding. The intermediate of dissociation with exposed Trp-1093 has a long lifetime (minutes) and may keep the PMCA primed for activation.
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Affiliation(s)
- John T Penniston
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA 02114, USA
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10
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Snijder J, Rose RJ, Raijmakers R, Heck AJ. Site-specific methionine oxidation in calmodulin affects structural integrity and interaction with Ca2+/calmodulin-dependent protein kinase II. J Struct Biol 2011; 174:187-95. [DOI: 10.1016/j.jsb.2010.12.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 12/02/2010] [Accepted: 12/08/2010] [Indexed: 10/18/2022]
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11
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Zaidi A. Plasma membrane Ca 2+-ATPases: Targets of oxidative stress in brain aging and neurodegeneration. World J Biol Chem 2010; 1:271-80. [PMID: 21537484 PMCID: PMC3083975 DOI: 10.4331/wjbc.v1.i9.271] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 08/20/2010] [Accepted: 08/27/2010] [Indexed: 02/05/2023] Open
Abstract
The plasma membrane Ca2+-ATPase (PMCA) pumps play an important role in the maintenance of precise levels of intracellular Ca2+ [Ca2+]i, essential to the functioning of neurons. In this article, we review evidence showing age-related changes of the PMCAs in synaptic plasma membranes (SPMs). PMCA activity and protein levels in SPMs diminish progressively with increasing age. The PMCAs are very sensitive to oxidative stress and undergo functional and structural changes when exposed to oxidants of physiological relevance. The major signatures of oxidative modification in the PMCAs are rapid inactivation, conformational changes, aggregation, internalization from the plasma membrane and proteolytic degradation. PMCA proteolysis appears to be mediated by both calpains and caspases. The predominance of one proteolytic pathway vs the other, the ensuing pattern of PMCA degradation and its consequence on pump activity depends largely on the type of insult, its intensity and duration. Experimental reduction of PMCA expression not only alters the dynamics of cellular Ca2+ handling but also has a myriad of downstream consequences on various aspects of cell function, indicating a broad role of these pumps. Age- and oxidation-related down-regulation of the PMCAs may play an important role in compromised neuronal function in the aging brain and its several-fold increased susceptibility to neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease, and stroke. Therapeutic approaches that protect the PMCAs and stabilize [Ca2+]i homeostasis may be capable of slowing and/or preventing neuronal degeneration. The PMCAs are therefore emerging as a new class of drug targets for therapeutic interventions in various chronic degenerative disorders.
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Affiliation(s)
- Asma Zaidi
- Asma Zaidi, Department of Biochemistry, Kansas City University of Medicine and Biosciences, Kansas City, MO 64106, United States
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12
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Juranic N, Atanasova E, Filoteo AG, Macura S, Prendergast FG, Penniston JT, Strehler EE. Calmodulin wraps around its binding domain in the plasma membrane Ca2+ pump anchored by a novel 18-1 motif. J Biol Chem 2009; 285:4015-4024. [PMID: 19996092 DOI: 10.1074/jbc.m109.060491] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Using solution NMR spectroscopy, we obtained the structure of Ca(2+)-calmodulin (holoCaM) in complex with peptide C28 from the binding domain of the plasma membrane Ca(2+)-ATPase (PMCA) pump isoform 4b. This provides the first atomic resolution insight into the binding mode of holoCaM to the full-length binding domain of PMCA. Structural comparison of the previously determined holoCaM.C20 complex with this holoCaM.C28 complex supports the idea that the initial binding step is represented by (holoCaM.C20) and the final bound complex by (holoCaM.C28). This affirms the existing multi-step kinetic model of PMCA4b activation by CaM. The complex exhibits a new binding motif in which holoCaM is wrapped around helical C28 peptide using two anchoring residues from the peptide at relative positions 18 and 1. The anchors correspond to Phe-1110 and Trp-1093, respectively, in full-length PMCA4b, and the peptide and CaM are oriented in an anti-parallel manner. This is a greater sequence distance between anchors than in any of the known holoCaM complexes with a helical peptide. Analysis of the geometry of holoCaM-peptide binding for the cases where the target peptide adopts an alpha(D)-helix with its anchors buried in the main hydrophobic pockets of the two CaM lobes establishes that only relative sequential positions of 10, 14, 17, and 18 are allowed for the second anchor.
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Affiliation(s)
- Nenad Juranic
- From the Departments of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905.
| | - Elena Atanasova
- From the Departments of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905
| | - Adelaida G Filoteo
- From the Departments of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905
| | - Slobodan Macura
- From the Departments of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905
| | - Franklyn G Prendergast
- From the Departments of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905; Departments of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, Minnesota 55905 and
| | | | - Emanuel E Strehler
- From the Departments of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905
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13
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Venezia CF, Meany BJ, Braz VA, Barkley MD. Kinetics of association and dissociation of HIV-1 reverse transcriptase subunits. Biochemistry 2009; 48:9084-93. [PMID: 19715314 DOI: 10.1021/bi9010495] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The biologically active form of HIV-1 reverse transcriptase (RT) is the p66/p51 heterodimer. The process of maturation of the heterodimer from precursor proteins is poorly understood. Previous studies indicated that association of p66 and p51 is very slow. Three techniques, a pre-steady-state activity assay, intrinsic tryptophan fluorescence, and a FRET assay, were used to monitor the dimerization kinetics of RT. Kinetic experiments were conducted with purified p66 and p51 proteins in aqueous buffer. All three techniques gave essentially the same results. The dissociation kinetics of p66/p51 were first-order with rate constants (k(diss)) of approximately 4 x 10(-6) s(-1) (t(1/2) = 48 h). The association kinetics of p66 and p51 were concentration-dependent with second-order rate constants (k(ass)) of approximately 1.7 M(-1) s(-1) for the simple bimolecular association reaction. The implications of slow dimerization of p66/p51 for the maturation process are discussed. A reaction-controlled model invoking conformational selection is proposed to explain the slow protein-protein association kinetics.
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Affiliation(s)
- Carl F Venezia
- Department of Chemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA
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14
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Gsponer J, Christodoulou J, Cavalli A, Bui JM, Richter B, Dobson CM, Vendruscolo M. A coupled equilibrium shift mechanism in calmodulin-mediated signal transduction. Structure 2008; 16:736-46. [PMID: 18462678 PMCID: PMC2428103 DOI: 10.1016/j.str.2008.02.017] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2007] [Revised: 02/15/2008] [Accepted: 02/18/2008] [Indexed: 11/25/2022]
Abstract
We used nuclear magnetic resonance data to determine ensembles of conformations representing the structure and dynamics of calmodulin (CaM) in the calcium-bound state (Ca(2+)-CaM) and in the state bound to myosin light chain kinase (CaM-MLCK). These ensembles reveal that the Ca(2+)-CaM state includes a range of structures similar to those present when CaM is bound to MLCK. Detailed analysis of the ensembles demonstrates that correlated motions within the Ca(2+)-CaM state direct the structural fluctuations toward complex-like substates. This phenomenon enables initial ligation of MLCK at the C-terminal domain of CaM and induces a population shift among the substates accessible to the N-terminal domain, thus giving rise to the cooperativity associated with binding. Based on these results and the combination of modern free energy landscape theory with classical allostery models, we suggest that a coupled equilibrium shift mechanism controls the efficient binding of CaM to a wide range of ligands.
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Affiliation(s)
- Jörg Gsponer
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
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15
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Long LH, Liu J, Liu RL, Wang F, Hu ZL, Xie N, Fu H, Chen JG. Differential Effects of Methionine and Cysteine Oxidation on [Ca2+]i in Cultured Hippocampal Neurons. Cell Mol Neurobiol 2008; 29:7-15. [DOI: 10.1007/s10571-008-9289-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2008] [Accepted: 06/06/2008] [Indexed: 12/23/2022]
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16
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Orihuela D. Effect of aluminium on duodenal calcium transport in pregnant and lactating rats treated with bromocriptine. J Inorg Biochem 2007; 101:1270-4. [PMID: 17629566 DOI: 10.1016/j.jinorgbio.2007.06.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Revised: 06/04/2007] [Accepted: 06/05/2007] [Indexed: 12/30/2022]
Abstract
The aim of present work was to study the effect of oral aluminium (Al) overload on intestinal calcium (Ca) absorption in the critical stages of pregnancy and lactation of rats and to find out possible relationships with prolactin (PRL) and 17beta-estradiol (E2) circulating levels. Adult female Wistar rats were orally treated from day 1 of pregnancy with 0 (control), or 50 mg elemental Al (as chloride)/kg body weight per day. Ca transport was determined by everted duodenal sacs technique using 2 microCi of (45)CaCl(2) as flux marker (JCa(ms)). Al treatment reduced JCa(ms) either in late pregnancy (day 19) or in middle lactation (day 9 postpartum). Oral administration of bromocriptine (BrC), an inhibitor of PRL secretion, at dose of 10 mg/kg body weight given 18 h before JCa(ms) measurements were done, produced a significant decrease in the inhibitory effect of Al on JCa(ms), expressed as percent of control, at day 9 of nursing (vehicle: 51+/-7%, BrC: 28+/-4%, P <0.05). A positive correlation between Al effects on JCa(ms) and the physiological variations of E2 serum levels along pregnancy and lactation in BrC-treated rats was also found (r(2)=0.277, P =0.001). We conclude Al could reduce transcellular Ca absorption in the duodenum by interfering with physiological mechanisms of Ca transport partially mediated by serum level increments of E2 and PRL, observed in late pregnancy and mainly during middle lactation of rats.
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Affiliation(s)
- Daniel Orihuela
- Laboratorio de Investigaciones Fisiológicas Experimentales, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Argentina.
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