1
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Pollard LW, Coscia SM, Rebowski G, Palmer NJ, Holzbaur ELF, Dominguez R, Ostap EM. Ensembles of human myosin-19 bound to calmodulin and regulatory light chain RLC12B drive multimicron transport. J Biol Chem 2023; 299:102906. [PMID: 36642185 PMCID: PMC9929473 DOI: 10.1016/j.jbc.2023.102906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 01/15/2023] Open
Abstract
Myosin-19 (Myo19) controls the size, morphology, and distribution of mitochondria, but the underlying role of Myo19 motor activity is unknown. Complicating mechanistic in vitro studies, the identity of the light chains (LCs) of Myo19 remains unsettled. Here, we show by coimmunoprecipitation, reconstitution, and proteomics that the three IQ motifs of human Myo19 expressed in Expi293 human cells bind regulatory light chain (RLC12B) and calmodulin (CaM). We demonstrate that overexpression of Myo19 in HeLa cells enhances the recruitment of both Myo19 and RLC12B to mitochondria, suggesting cellular association of RLC12B with the motor. Further experiments revealed that RLC12B binds IQ2 and is flanked by two CaM molecules. In vitro, we observed that the maximal speed (∼350 nm/s) occurs when Myo19 is supplemented with CaM, but not RLC12B, suggesting maximal motility requires binding of CaM to IQ-1 and IQ-3. The addition of calcium slowed actin gliding (∼200 nm/s) without an apparent effect on CaM affinity. Furthermore, we show that small ensembles of Myo19 motors attached to quantum dots can undergo processive runs over several microns, and that calcium reduces the attachment frequency and run length of Myo19. Together, our data are consistent with a model where a few single-headed Myo19 molecules attached to a mitochondrion can sustain prolonged motile associations with actin in a CaM- and calcium-dependent manner. Based on these properties, we propose that Myo19 can function in mitochondria transport along actin filaments, tension generation on multiple randomly oriented filaments, and/or pushing against branched actin networks assembled near the membrane surface.
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Affiliation(s)
- Luther W Pollard
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA; Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Stephen M Coscia
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA; Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA; Cell and Molecular Biology Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Grzegorz Rebowski
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA; Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Nicholas J Palmer
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA; Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA; Biochemistry and Molecular Biophysics Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Erika L F Holzbaur
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA; Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Roberto Dominguez
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA; Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA.
| | - E Michael Ostap
- Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA; Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA.
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2
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Yang CF, Tsai WC. Calmodulin: The switch button of calcium signaling. Tzu Chi Med J 2022; 34:15-22. [PMID: 35233351 PMCID: PMC8830543 DOI: 10.4103/tcmj.tcmj_285_20] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 03/17/2021] [Accepted: 05/06/2021] [Indexed: 11/25/2022] Open
Abstract
Calmodulin (CaM), a calcium sensor, decodes the critical calcium-dependent signals and converts them into the driving force to control various important cellular functions, such as ion transport. This small protein has a short central linker to connect two globular lobes and each unit is composed of a pair of homologous domains (HD) which are responsible for calcium binding. The conformation of each HD is sensitive to the levels of the intracellular Ca2+ concentrations while the flexible structure of the central domain enables its interactions with hundreds of cellular proteins. Apart from calcium binding, posttranslational modifications (PTMs) also contribute to the modulations of CaM functions by affecting its protein-protein interaction networks and hence drawing out the various downstream signaling cascades. In this mini-review, we first aim to elucidate the structural features of CaM and then overview the recent studies on the engagements of calcium binding and PTMs in Ca2+/CaM-mediated conformational alterations and signaling events. The mechanistic understanding of CaM working models is expected to be a key to decipher the precise role of CaM in cardiac physiology and disease pathology.
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3
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Zea DJ, Laskina S, Baudin A, Richard H, Laine E. Assessing conservation of alternative splicing with evolutionary splicing graphs. Genome Res 2021; 31:1462-1473. [PMID: 34266979 PMCID: PMC8327911 DOI: 10.1101/gr.274696.120] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 06/11/2021] [Indexed: 12/29/2022]
Abstract
Understanding how protein function has evolved and diversified is of great importance for human genetics and medicine. Here, we tackle the problem of describing the whole transcript variability observed in several species by generalizing the definition of splicing graph. We provide a practical solution to construct parsimonious evolutionary splicing graphs where each node is a minimal transcript building block defined across species. We show a clear link between the functional relevance, tissue regulation, and conservation of alternative transcripts on a set of 50 genes. By scaling up to the whole human protein-coding genome, we identify a few thousand genes where alternative splicing modulates the number and composition of pseudorepeats. We have implemented our approach in ThorAxe, an efficient, versatile, robust, and freely available computational tool.
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Affiliation(s)
- Diego Javier Zea
- Sorbonne Université, CNRS, IBPS, Laboratoire de Biologie Computationnelle et Quantitative (LCQB), 75005 Paris, France
| | - Sofya Laskina
- Bioinformatics Unit (MF1), Department for Methods Development and Research Infrastructure, Robert Koch Institute, 13353 Berlin, Germany
| | - Alexis Baudin
- Sorbonne Université, CNRS, LIP6, F-75005 Paris, France
| | - Hugues Richard
- Sorbonne Université, CNRS, IBPS, Laboratoire de Biologie Computationnelle et Quantitative (LCQB), 75005 Paris, France
- Bioinformatics Unit (MF1), Department for Methods Development and Research Infrastructure, Robert Koch Institute, 13353 Berlin, Germany
| | - Elodie Laine
- Sorbonne Université, CNRS, IBPS, Laboratoire de Biologie Computationnelle et Quantitative (LCQB), 75005 Paris, France
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4
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Pazicky S, Dhamotharan K, Kaszuba K, Mertens HDT, Gilberger T, Svergun D, Kosinski J, Weininger U, Löw C. Structural role of essential light chains in the apicomplexan glideosome. Commun Biol 2020; 3:568. [PMID: 33051581 PMCID: PMC7555893 DOI: 10.1038/s42003-020-01283-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 09/11/2020] [Indexed: 01/18/2023] Open
Abstract
Gliding, a type of motility based on an actin-myosin motor, is specific to apicomplexan parasites. Myosin A binds two light chains which further interact with glideosome associated proteins and assemble into the glideosome. The role of individual glideosome proteins is unclear due to the lack of structures of larger glideosome assemblies. Here, we investigate the role of essential light chains (ELCs) in Toxoplasma gondii and Plasmodium falciparum and present their crystal structures as part of trimeric sub-complexes. We show that although ELCs bind a conserved MyoA sequence, P. falciparum ELC adopts a distinct structure in the free and MyoA-bound state. We suggest that ELCs enhance MyoA performance by inducing secondary structure in MyoA and thus stiffen its lever arm. Structural and biophysical analysis reveals that calcium binding has no influence on the structure of ELCs. Our work represents a further step towards understanding the mechanism of gliding in Apicomplexa.
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Affiliation(s)
- Samuel Pazicky
- Centre for Structural Systems Biology (CSSB), Notkestrasse 85, D-22607, Hamburg, Germany
- Molecular Biology Laboratory (EMBL), Hamburg Unit c/o Deutsches Elektronen Synchrotron (DESY), Notkestrasse 85, D-22607, Hamburg, Germany
| | - Karthikeyan Dhamotharan
- Centre for Structural Systems Biology (CSSB), Notkestrasse 85, D-22607, Hamburg, Germany
- Molecular Biology Laboratory (EMBL), Hamburg Unit c/o Deutsches Elektronen Synchrotron (DESY), Notkestrasse 85, D-22607, Hamburg, Germany
| | - Karol Kaszuba
- Centre for Structural Systems Biology (CSSB), Notkestrasse 85, D-22607, Hamburg, Germany
- Molecular Biology Laboratory (EMBL), Hamburg Unit c/o Deutsches Elektronen Synchrotron (DESY), Notkestrasse 85, D-22607, Hamburg, Germany
| | - Haydyn D T Mertens
- Molecular Biology Laboratory (EMBL), Hamburg Unit c/o Deutsches Elektronen Synchrotron (DESY), Notkestrasse 85, D-22607, Hamburg, Germany
| | - Tim Gilberger
- Centre for Structural Systems Biology (CSSB), Notkestrasse 85, D-22607, Hamburg, Germany
- Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Strasse 74, D-20359, Hamburg, Germany
- Department of Biology, University of Hamburg, Hamburg, Germany
| | - Dmitri Svergun
- Molecular Biology Laboratory (EMBL), Hamburg Unit c/o Deutsches Elektronen Synchrotron (DESY), Notkestrasse 85, D-22607, Hamburg, Germany
| | - Jan Kosinski
- Centre for Structural Systems Biology (CSSB), Notkestrasse 85, D-22607, Hamburg, Germany
- Molecular Biology Laboratory (EMBL), Hamburg Unit c/o Deutsches Elektronen Synchrotron (DESY), Notkestrasse 85, D-22607, Hamburg, Germany
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117, Heidelberg, Germany
| | - Ulrich Weininger
- Martin-Luther-University Halle-Wittenberg, Institute of Physics, Biophysics, D-06120, Halle (Saale), Germany
| | - Christian Löw
- Centre for Structural Systems Biology (CSSB), Notkestrasse 85, D-22607, Hamburg, Germany.
- Molecular Biology Laboratory (EMBL), Hamburg Unit c/o Deutsches Elektronen Synchrotron (DESY), Notkestrasse 85, D-22607, Hamburg, Germany.
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5
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Pitt GS, Lee SY. Ca 2+/CaM interaction with voltage-gated Na + channels. Proc Natl Acad Sci U S A 2019; 116:26150-26151. [PMID: 31796599 PMCID: PMC6936364 DOI: 10.1073/pnas.1909835116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Geoffrey S. Pitt
- Cardiovascular Research Institute, Weill Cornell Medical College, New York, NY 10021
| | - Seok-Yong Lee
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710
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6
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Barger SR, James ML, Pellenz CD, Krendel M, Sirotkin V. Human myosin 1e tail but not motor domain replaces fission yeast Myo1 domains to support myosin-I function during endocytosis. Exp Cell Res 2019; 384:111625. [PMID: 31542284 DOI: 10.1016/j.yexcr.2019.111625] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 09/13/2019] [Accepted: 09/15/2019] [Indexed: 10/26/2022]
Abstract
In both unicellular and multicellular organisms, long-tailed class I myosins function in clathrin-mediated endocytosis. Myosin 1e (Myo1e) in vertebrates and Myo1 in fission yeast have similar domain organization, yet whether these proteins or their individual protein domains are functionally interchangeable remains unknown. In an effort to assess functional conservation of class I myosins, we tested whether human Myo1e could replace Myo1 in fission yeast Schizosaccharomyces pombe and found that it was unable to substitute for yeast Myo1. To determine if any individual protein domain is responsible for the inability of Myo1e to function in yeast, we created human-yeast myosin-I chimeras. By functionally testing these chimeric myosins in vivo, we concluded that the Myo1e motor domain is unable to function in yeast, even when combined with the yeast Myo1 tail and a full complement of yeast regulatory light chains. Conversely, the Myo1e tail, when attached to the yeast Myo1 motor domain, supports localization to endocytic actin patches and partially rescues the endocytosis defect in myo1Δ cells. Further dissection showed that both the TH1 and TH2-SH3 domains in the human Myo1e tail are required for localization and function of chimeric myosin-I at endocytic sites. Overall, this study provides insights into the role of individual myosin-I domains, expands the utility of fission yeast as a simple model system to study the effects of disease-associated MYO1E mutations, and supports a model of co-evolution between a myosin motor and its actin track.
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Affiliation(s)
- Sarah R Barger
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, NY, 13210, USA
| | - Michael L James
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, NY, 13210, USA
| | - Christopher D Pellenz
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, NY, 13210, USA
| | - Mira Krendel
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, NY, 13210, USA.
| | - Vladimir Sirotkin
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, NY, 13210, USA.
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7
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Archer CR, Enslow BT, Taylor AB, De la Rosa V, Bhattacharya A, Shapiro MS. A mutually induced conformational fit underlies Ca 2+-directed interactions between calmodulin and the proximal C terminus of KCNQ4 K + channels. J Biol Chem 2019; 294:6094-6112. [PMID: 30808708 PMCID: PMC6463706 DOI: 10.1074/jbc.ra118.006857] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 02/24/2019] [Indexed: 11/06/2022] Open
Abstract
Calmodulin (CaM) conveys intracellular Ca2+ signals to KCNQ (Kv7, "M-type") K+ channels and many other ion channels. Whether this "calmodulation" involves a dramatic structural rearrangement or only slight perturbations of the CaM/KCNQ complex is as yet unclear. A consensus structural model of conformational shifts occurring between low nanomolar and physiologically high intracellular [Ca2+] is still under debate. Here, we used various techniques of biophysical chemical analyses to investigate the interactions between CaM and synthetic peptides corresponding to the A and B domains of the KCNQ4 subtype. We found that in the absence of CaM, the peptides are disordered, whereas Ca2+/CaM imposed helical structure on both KCNQ A and B domains. Isothermal titration calorimetry revealed that Ca2+/CaM has higher affinity for the B domain than for the A domain of KCNQ2-4 and much higher affinity for the B domain when prebound with the A domain. X-ray crystallography confirmed that these discrete peptides spontaneously form a complex with Ca2+/CaM, similar to previous reports of CaM binding KCNQ-AB domains that are linked together. Microscale thermophoresis and heteronuclear single-quantum coherence NMR spectroscopy indicated the C-lobe of Ca2+-free CaM to interact with the KCNQ4 B domain (Kd ∼10-20 μm), with increasing Ca2+ molar ratios shifting the CaM-B domain interactions via only the CaM C-lobe to also include the N-lobe. Our findings suggest that in response to increased Ca2+, CaM undergoes lobe switching that imposes a dramatic mutually induced conformational fit to both the proximal C terminus of KCNQ4 channels and CaM, likely underlying Ca2+-dependent regulation of KCNQ gating.
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Affiliation(s)
- Crystal R Archer
- From the Departments of Cell and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas 78229; Departments of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Benjamin T Enslow
- the Long School of Medicine, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Alexander B Taylor
- Departments of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Victor De la Rosa
- From the Departments of Cell and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Akash Bhattacharya
- Departments of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Mark S Shapiro
- From the Departments of Cell and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas 78229.
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8
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Yadav S, Sitbon YH, Kazmierczak K, Szczesna-Cordary D. Hereditary heart disease: pathophysiology, clinical presentation, and animal models of HCM, RCM, and DCM associated with mutations in cardiac myosin light chains. Pflugers Arch 2019; 471:683-699. [PMID: 30706179 DOI: 10.1007/s00424-019-02257-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 12/26/2018] [Accepted: 01/13/2019] [Indexed: 02/07/2023]
Abstract
Genetic cardiomyopathies, a group of cardiovascular disorders based on ventricular morphology and function, are among the leading causes of morbidity and mortality worldwide. Such genetically driven forms of hypertrophic (HCM), dilated (DCM), and restrictive (RCM) cardiomyopathies are chronic, debilitating diseases that result from biomechanical defects in cardiac muscle contraction and frequently progress to heart failure (HF). Locus and allelic heterogeneity, as well as clinical variability combined with genetic and phenotypic overlap between different cardiomyopathies, have challenged proper clinical prognosis and provided an incentive for identification of pathogenic variants. This review attempts to provide an overview of inherited cardiomyopathies with a focus on their genetic etiology in myosin regulatory (RLC) and essential (ELC) light chains, which are EF-hand protein family members with important structural and regulatory roles. From the clinical discovery of cardiomyopathy-linked light chain mutations in patients to an array of exploratory studies in animals, and reconstituted and recombinant systems, we have summarized the current state of knowledge on light chain mutations and how they induce physiological disease states via biochemical and biomechanical alterations at the molecular, tissue, and organ levels. Cardiac myosin RLC phosphorylation and the N-terminus ELC have been discussed as two important emerging modalities with important implications in the regulation of myosin motor function, and thus cardiac performance. A comprehensive understanding of such triggers is absolutely necessary for the development of target-specific rescue strategies to ameliorate or reverse the effects of myosin light chain-related inherited cardiomyopathies.
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MESH Headings
- Animals
- Cardiomyopathy, Dilated/etiology
- Cardiomyopathy, Dilated/genetics
- Cardiomyopathy, Dilated/pathology
- Cardiomyopathy, Hypertrophic/etiology
- Cardiomyopathy, Hypertrophic/genetics
- Cardiomyopathy, Hypertrophic/pathology
- Cardiomyopathy, Restrictive/etiology
- Cardiomyopathy, Restrictive/genetics
- Cardiomyopathy, Restrictive/pathology
- Disease Models, Animal
- Humans
- Mutation
- Myosin Light Chains/genetics
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Affiliation(s)
- Sunil Yadav
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, 1600 NW 10th Ave., Miami, FL, 33136, USA
| | - Yoel H Sitbon
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, 1600 NW 10th Ave., Miami, FL, 33136, USA
| | - Katarzyna Kazmierczak
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, 1600 NW 10th Ave., Miami, FL, 33136, USA
| | - Danuta Szczesna-Cordary
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, 1600 NW 10th Ave., Miami, FL, 33136, USA.
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9
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Li X, Wu G, Yang Y, Fu S, Liu X, Kang H, Yang X, Su XC, Shen Y. Calmodulin dissociates the STIM1-Orai1 complex and STIM1 oligomers. Nat Commun 2017; 8:1042. [PMID: 29051492 PMCID: PMC5648805 DOI: 10.1038/s41467-017-01135-w] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Accepted: 08/22/2017] [Indexed: 01/20/2023] Open
Abstract
Store-operated calcium entry (SOCE) is a major pathway for calcium ions influx into cells and has a critical role in various cell functions. Here we demonstrate that calcium-bound calmodulin (Ca2+-CaM) binds to the core region of activated STIM1. This interaction facilitates slow Ca2+-dependent inactivation after Orai1 channel activation by wild-type STIM1 or a constitutively active STIM1 mutant. We define the CaM-binding site in STIM1, which is adjacent to the STIM1-Orai1 coupling region. The binding of Ca2+-CaM to activated STIM1 disrupts the STIM1-Orai1 complex and also disassembles STIM1 oligomer. Based on these results we propose a model for the calcium-bound CaM-regulated deactivation of SOCE.
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Affiliation(s)
- Xin Li
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin, 300071, China
| | - Guangyan Wu
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin, 300071, China
| | - Yin Yang
- State Key Laboratory of Elemento-Organic Chemistry and College of Chemistry, Nankai University, 94 Weijin Road, Tianjin, 300071, China
| | - Shijuan Fu
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin, 300071, China
| | - Xiaofen Liu
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin, 300071, China
| | - Huimin Kang
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin, 300071, China
| | - Xue Yang
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin, 300071, China.
| | - Xun-Cheng Su
- State Key Laboratory of Elemento-Organic Chemistry and College of Chemistry, Nankai University, 94 Weijin Road, Tianjin, 300071, China. .,Synergetic Innovation Center of Chemical Science and Engineering, 94 Weijin Road, Tianjin, 300071, China.
| | - Yuequan Shen
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin, 300071, China. .,Synergetic Innovation Center of Chemical Science and Engineering, 94 Weijin Road, Tianjin, 300071, China.
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10
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Powell CJ, Jenkins ML, Parker ML, Ramaswamy R, Kelsen A, Warshaw DM, Ward GE, Burke JE, Boulanger MJ. Dissecting the molecular assembly of the Toxoplasma gondii MyoA motility complex. J Biol Chem 2017; 292:19469-19477. [PMID: 28972141 DOI: 10.1074/jbc.m117.809632] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 09/22/2017] [Indexed: 01/28/2023] Open
Abstract
Apicomplexan parasites such as Toxoplasma gondii rely on a unique form of locomotion known as gliding motility. Generating the mechanical forces to support motility are divergent class XIV myosins (MyoA) coordinated by accessory proteins known as light chains. Although the importance of the MyoA-light chain complex is well-established, the detailed mechanisms governing its assembly and regulation are relatively unknown. To establish a molecular blueprint of this dynamic complex, we first mapped the adjacent binding sites of light chains MLC1 and ELC1 on the MyoA neck (residues 775-818) using a combination of hydrogen-deuterium exchange mass spectrometry and isothermal titration calorimetry. We then determined the 1.85 Å resolution crystal structure of MLC1 in complex with its cognate MyoA peptide. Structural analysis revealed a bilobed architecture with MLC1 clamping tightly around the helical MyoA peptide, consistent with the stable 10 nm Kd measured by isothermal titration calorimetry. We next showed that coordination of calcium by an EF-hand in ELC1 and prebinding of MLC1 to the MyoA neck enhanced the affinity of ELC1 for the MyoA neck 7- and 8-fold, respectively. When combined, these factors enhanced ELC1 binding 49-fold (to a Kd of 12 nm). Using the full-length MyoA motor (residues 1-831), we then showed that, in addition to coordinating the neck region, ELC1 appears to engage the MyoA converter subdomain, which couples the motor domain to the neck. These data support an assembly model where staged binding events cooperate to yield high-affinity complexes that are able to maximize force transduction.
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Affiliation(s)
- Cameron J Powell
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada and
| | - Meredith L Jenkins
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada and
| | - Michelle L Parker
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada and
| | - Raghavendran Ramaswamy
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada and
| | - Anne Kelsen
- the Departments of Microbiology and Molecular Genetics and
| | - David M Warshaw
- Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405
| | - Gary E Ward
- the Departments of Microbiology and Molecular Genetics and
| | - John E Burke
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada and
| | - Martin J Boulanger
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada and
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11
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Li L, Xing Y, Chang D, Fang S, Cui B, Li Q, Wang X, Guo S, Yang X, Men S, Shen Y. CaM/BAG5/Hsc70 signaling complex dynamically regulates leaf senescence. Sci Rep 2016; 6:31889. [PMID: 27539741 PMCID: PMC4990970 DOI: 10.1038/srep31889] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 07/28/2016] [Indexed: 02/01/2023] Open
Abstract
Calcium signaling plays an essential role in plant cell physiology, and chaperone-mediated protein folding directly regulates plant programmed cell death. The Arabidopsis thaliana protein AtBAG5 (Bcl-2-associated athanogene 5) is unique in that it contains both a BAG domain capable of binding Hsc70 (Heat shock cognate protein 70) and a characteristic IQ motif that is specific for Ca(2+)-free CaM (Calmodulin) binding and hence acts as a hub linking calcium signaling and the chaperone system. Here, we determined crystal structures of AtBAG5 alone and in complex with Ca(2+)-free CaM. Structural and biochemical studies revealed that Ca(2+)-free CaM and Hsc70 bind AtBAG5 independently, whereas Ca(2+)-saturated CaM and Hsc70 bind AtBAG5 with negative cooperativity. Further in vivo studies confirmed that AtBAG5 localizes to mitochondria and that its overexpression leads to leaf senescence symptoms including decreased chlorophyll retention and massive ROS production in dark-induced plants. Mutants interfering the CaM/AtBAG5/Hsc70 complex formation leads to different phenotype of leaf senescence. Collectively, we propose that the CaM/AtBAG5/Hsc70 signaling complex plays an important role in regulating plant senescence.
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Affiliation(s)
- Luhua Li
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, Tianjin 300071, China
- College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Yangfei Xing
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, Tianjin 300071, China
- College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Dong Chang
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, Tianjin 300071, China
- College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Shasha Fang
- College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Boyang Cui
- College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Qi Li
- College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Xuejie Wang
- College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Shang Guo
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Xue Yang
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Shuzhen Men
- College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Yuequan Shen
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, Tianjin 300071, China
- College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China
- Synergetic Innovation Center of Chemical Science and Engineering, 94 Weijin Road, Tianjin 300071, China
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12
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Pitt GS, Lee SY. Current view on regulation of voltage-gated sodium channels by calcium and auxiliary proteins. Protein Sci 2016; 25:1573-84. [PMID: 27262167 DOI: 10.1002/pro.2960] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Accepted: 05/31/2016] [Indexed: 11/09/2022]
Abstract
In cardiac and skeletal myocytes, and in most neurons, the opening of voltage-gated Na(+) channels (NaV channels) triggers action potentials, a process that is regulated via the interactions of the channels' intercellular C-termini with auxiliary proteins and/or Ca(2+) . The molecular and structural details for how Ca(2+) and/or auxiliary proteins modulate NaV channel function, however, have eluded a concise mechanistic explanation and details have been shrouded for the last decade behind controversy about whether Ca(2+) acts directly upon the NaV channel or through interacting proteins, such as the Ca(2+) binding protein calmodulin (CaM). Here, we review recent advances in defining the structure of NaV intracellular C-termini and associated proteins such as CaM or fibroblast growth factor homologous factors (FHFs) to reveal new insights into how Ca(2+) affects NaV function, and how altered Ca(2+) -dependent or FHF-mediated regulation of NaV channels is perturbed in various disease states through mutations that disrupt CaM or FHF interaction.
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Affiliation(s)
- Geoffrey S Pitt
- Cardiovascular Research Institute, Weill Cornell Medicine, New York, NY, 10065
| | - Seok-Yong Lee
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, 27710
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13
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Heissler SM, Sellers JR. Various Themes of Myosin Regulation. J Mol Biol 2016; 428:1927-46. [PMID: 26827725 DOI: 10.1016/j.jmb.2016.01.022] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 01/12/2016] [Accepted: 01/19/2016] [Indexed: 10/24/2022]
Abstract
Members of the myosin superfamily are actin-based molecular motors that are indispensable for cellular homeostasis. The vast functional and structural diversity of myosins accounts for the variety and complexity of the underlying allosteric regulatory mechanisms that determine the activation or inhibition of myosin motor activity and enable precise timing and spatial aspects of myosin function at the cellular level. This review focuses on the molecular basis of posttranslational regulation of eukaryotic myosins from different classes across species by allosteric intrinsic and extrinsic effectors. First, we highlight the impact of heavy and light chain phosphorylation. Second, we outline intramolecular regulatory mechanisms such as autoinhibition and subsequent activation. Third, we discuss diverse extramolecular allosteric mechanisms ranging from actin-linked regulatory mechanisms to myosin:cargo interactions. At last, we briefly outline the allosteric regulation of myosins with synthetic compounds.
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Affiliation(s)
- Sarah M Heissler
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, 50 South Drive, B50/3529, Bethesda, MD 20892-8015, USA.
| | - James R Sellers
- Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, 50 South Drive, B50/3529, Bethesda, MD 20892-8015, USA
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14
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Kovalevskaya NV, van de Waterbeemd M, Bokhovchuk FM, Bate N, Bindels RJM, Hoenderop JGJ, Vuister GW. Structural analysis of calmodulin binding to ion channels demonstrates the role of its plasticity in regulation. Pflugers Arch 2013; 465:1507-19. [PMID: 23609407 DOI: 10.1007/s00424-013-1278-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 03/18/2013] [Accepted: 04/02/2013] [Indexed: 12/17/2022]
Abstract
The Ca²⁺-binding protein calmodulin (CaM) is a well-known regulator of ion-channel activity. Consequently, the Protein Data Bank contains many structures of CaM in complex with different fragments of ion channels that together display a variety of binding modes. In addition to the canonical interaction, in which CaM engages its target with both its domains, many of the ion-channel-CaM complexes demonstrate alternative non-canonical binding modes that depend on the target and experimental conditions. Based on these findings, several mechanisms of ion-channel regulation by CaM have been proposed, all exploiting its plasticity and flexibility in interacting with its targets. In this review, we focus on complexes of CaM with either the voltage-gated calcium channels; the voltage-gated sodium channels or the small conductance calcium-activated potassium channels, for which both structural and functional data are available. For each channel, the functional relevance of these structural data and possible mechanism of calcium-dependent (in)activation and/or facilitation are discussed in detail.
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Affiliation(s)
- Nadezda V Kovalevskaya
- Department of Physiology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Geert Grooteplein Zuid 26-28, Nijmegen, 6525, GA, The Netherlands
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15
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Lewis JH, Greenberg MJ, Laakso JM, Shuman H, Ostap EM. Calcium regulation of myosin-I tension sensing. Biophys J 2012; 102:2799-807. [PMID: 22735530 DOI: 10.1016/j.bpj.2012.05.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 05/07/2012] [Accepted: 05/09/2012] [Indexed: 11/26/2022] Open
Abstract
Myo1b is a myosin that is exquisitely sensitive to tension. Its actin-attachment lifetime increases > 50-fold when its working stroke is opposed by 1 pN of force. The long attachment lifetime of myo1b under load raises the question: how are actin attachments that last >50 s in the presence of force regulated? Like most myosins, forces are transmitted to the myo1b motor through a light-chain binding domain that is structurally stabilized by calmodulin, a calcium-binding protein. Thus, we examined the effect of calcium on myo1b motility using ensemble and single-molecule techniques. Calcium accelerates key biochemical transitions on the ATPase pathway, decreases the working-stroke displacement, and greatly reduces the ability of myo1b to sense tension. Thus, calcium provides an effective mechanism for inhibiting motility and terminating long-duration attachments.
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Affiliation(s)
- John H Lewis
- Pennsylvania Muscle Institute and Department of Physiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
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16
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Beausang JF, Sun Y, Quinlan ME, Forkey JN, Goldman YE. Fluorescent labeling of calmodulin with bifunctional rhodamine. Cold Spring Harb Protoc 2012; 2012:2012/5/pdb.prot069351. [PMID: 22550304 DOI: 10.1101/pdb.prot069351] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Polarized total internal reflection fluorescence microscopy (polTIRFM) can be used to detect the spatial orientation and rotational dynamics of single molecules. polTIRFM determines the three-dimensional angular orientation and the extent of wobble of a fluorescent probe bound to the macromolecule of interest. This protocol describes how to label chicken calmodulin (CaM) with bifunctional rhodamine (BR) at two engineered cysteine (Cys) residues (P66C and A73C) so that it cross-links the two Cys sites. The resulting BR-CaM protein is then purified by high-performance liquid chromatography (HPLC) and concentrated by filter centrifugation. To confirm that the two Cys residues in the labeled CaM are actually cross-linked by BR, a sample of purified BR-CaM is digested by an endoproteinase and analyzed by mass spectrometry. The BR-CaM can then be used to label myosin V, which can in turn be used in a polTIRFM processive motility assay.
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17
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Ni S, Hong F, Haldeman BD, Baker JE, Facemyer KC, Cremo CR. Modification of interface between regulatory and essential light chains hampers phosphorylation-dependent activation of smooth muscle myosin. J Biol Chem 2012; 287:22068-79. [PMID: 22549781 DOI: 10.1074/jbc.m112.343491] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We examined the regulatory importance of interactions between regulatory light chain (RLC), essential light chain (ELC), and adjacent heavy chain (HC) in the regulatory domain of smooth muscle heavy meromyosin. After mutating the HC, RLC, and/or ELC to disrupt their predicted interactions (using scallop myosin coordinates), we measured basal ATPase, V(max), and K(ATPase) of actin-activated ATPase, actin-sliding velocities, rigor binding to actin, and kinetics of ATP binding and ADP release. If unphosphorylated, all mutants were similar to wild type showing turned-off behaviors. In contrast, if phosphorylated, mutation of RLC residues smM129Q and smG130C in the F-G helix linker, which interact with the ELC (Ca(2+) binding in scallop), was sufficient to abolish motility and diminish ATPase activity, without altering other parameters. ELC mutations within this interacting ELC loop (smR20M and smK25A) were normal, but smM129Q/G130C-R20M or -K25A showed a partially recovered phenotype suggesting that interaction between the RLC and ELC is important. A molecular dynamics study suggested that breaking the RLC/ELC interface leads to increased flexibility at the interface and ELC-binding site of the HC. We hypothesize that this leads to hampered activation by allowing a pre-existing equilibrium between activated and inhibited structural distributions (Vileno, B., Chamoun, J., Liang, H., Brewer, P., Haldeman, B. D., Facemyer, K. C., Salzameda, B., Song, L., Li, H. C., Cremo, C. R., and Fajer, P. G. (2011) Broad disorder and the allosteric mechanism of myosin II regulation by phosphorylation. Proc. Natl. Acad. Sci. U.S.A. 108, 8218-8223) to be biased strongly toward the inhibited distribution even when the RLC is phosphorylated. We propose that an important structural function of RLC phosphorylation is to promote or assist in the maintenance of an intact RLC/ELC interface. If the RLC/ELC interface is broken, the off-state structures are no longer destabilized by phosphorylation.
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Affiliation(s)
- Shaowei Ni
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, Nevada 89557, USA
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18
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Beausang JF, Sun Y, Quinlan ME, Forkey JN, Goldman YE. Orientation and rotational motions of single molecules by polarized total internal reflection fluorescence microscopy (polTIRFM). Cold Spring Harb Protoc 2012; 2012:2012/5/pdb.top069344. [PMID: 22550303 DOI: 10.1101/pdb.top069344] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In this article, we describe methods to detect the spatial orientation and rotational dynamics of single molecules using polarized total internal reflection fluorescence microscopy (polTIRFM). polTIRFM determines the three-dimensional angular orientation and the extent of wobble of a fluorescent probe bound to the macromolecule of interest. We discuss single-molecule versus ensemble measurements, as well as single-molecule techniques for orientation and rotation, and fluorescent probes for orientation studies. Using calmodulin (CaM) as an example of a target protein, we describe a method for labeling CaM with bifunctional rhodamine (BR). We also describe the physical principles and experimental setup of polTIRFM. We conclude with a brief introduction to assays using polTIRFM to assess the interaction of actin and myosin.
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19
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Chagot B, Chazin WJ. Solution NMR structure of Apo-calmodulin in complex with the IQ motif of human cardiac sodium channel NaV1.5. J Mol Biol 2010; 406:106-19. [PMID: 21167176 DOI: 10.1016/j.jmb.2010.11.046] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2010] [Revised: 11/22/2010] [Accepted: 11/23/2010] [Indexed: 12/19/2022]
Abstract
The function of the human voltage-gated sodium channel Na(V)1.5 is regulated in part by intracellular calcium signals. The ubiquitous calcium sensor protein calmodulin (CaM) is an important part of the complex calcium-sensing apparatus in Na(V)1.5. CaM interacts with an IQ (isoleucine-glutamine) motif in the large intracellular C-terminal domain of the channel. Using co-expression and co-purification, we have been able to isolate a CaM-IQ motif complex and to determine its high-resolution structure in absence of calcium using multi-dimensional solution NMR. Under these conditions, the Na(V)1.5 IQ motif interacts with the C-terminal domain (C-lobe) of CaM, with the N-terminal domain remaining free in solution. The structure reveals that the C-lobe adopts a semi-open conformation with the IQ motif bound in a narrow hydrophobic groove. Sequence similarities between voltage-gated sodium channels and voltage-gated calcium channels suggest that the structure of the CaM-Na(V)1.5 IQ motif complex can serve as a general model for the interaction between CaM and ion channel IQ motifs under low-calcium conditions. The structure also provides insight into the biochemical basis for disease-associated mutations that map to the IQ motif in Na(V)1.5.
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Affiliation(s)
- Benjamin Chagot
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37232, USA
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20
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McConnell RE, Tyska MJ. Leveraging the membrane - cytoskeleton interface with myosin-1. Trends Cell Biol 2010; 20:418-26. [PMID: 20471271 DOI: 10.1016/j.tcb.2010.04.004] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 04/15/2010] [Accepted: 04/16/2010] [Indexed: 12/19/2022]
Abstract
Class 1 myosins are small motor proteins with the ability to simultaneously bind to actin filaments and cellular membranes. Given their ability to generate mechanical force, and their high prevalence in many cell types, these molecules are well positioned to carry out several important biological functions at the interface of membrane and the actin cytoskeleton. Indeed, recent studies implicate these motors in endocytosis, exocytosis, release of extracellular vesicles, and the regulation of tension between membrane and the cytoskeleton. Many class 1 myosins also exhibit a load-dependent mechano-chemical cycle that enables them to maintain tension for long periods of time without hydrolyzing ATP. These properties put myosins-1 in a unique position to regulate dynamic membrane-cytoskeleton interactions and respond to physical forces during these events.
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Affiliation(s)
- Russell E McConnell
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37205, USA
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21
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O'Donnell SE, Newman RA, Witt TJ, Hultman R, Froehlig JR, Christensen AP, Shea MA. Thermodynamics and conformational change governing domain-domain interactions of calmodulin. Methods Enzymol 2009; 466:503-26. [PMID: 21609874 DOI: 10.1016/s0076-6879(09)66021-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Calmodulin (CaM) is a small (148 amino acid), ubiquitously expressed eukaryotic protein essential for Ca(2+) regulation and signaling. This highly acidic polypeptide (pI<4) has two homologous domains (N and C), each consisting of two EF-hand Ca(2+)-binding sites. Despite significant homology, the domains have intrinsic differences in their Ca(2+)-binding properties and separable roles in regulating physiological targets such as kinases and ion channels. In mammalian full-length CaM, sites III and IV in the C-domain bind Ca(2+) cooperatively with ~10-fold higher affinity than sites I and II in the N-domain. However, the difference is only twofold when CaM is severed at residue 75, indicating that anticooperative interactions occur in full-length CaM. The Ca(2+)-binding properties of sites I and II are regulated by several factors including the interplay of interdomain linker residues far from the binding sites. Our prior thermodynamic studies showed that these residues inhibit thermal denaturation and decrease calcium affinity. Based on high-resolution structures and NMR spectra, there appear to be interactions between charged residues in the sequence 75-80 and those near the amino terminus of CaM. To explore electrostatic contributions to interdomain interactions in CaM, KCl was used to perturb the Ca(2+)-binding affinity, thermal stability, and hydrodynamic size of a nested set of recombinant mammalian CaM (rCaM) fragments terminating at residues 75, 80, 85, or 90. Potassium chloride is known to decrease Ca(2+)-binding affinity of full-length CaM. It may act directly by competition with acidic side chains that chelate Ca(2+) in the binding sites, and indirectly elsewhere in the molecule by changing tertiary constraints and conformation. In all proteins studied, KCl decreased Ca(2+)-affinity, decreased Stokes radius, and increased thermal stability, but not monotonically. Crystallographic structures of Ca(2+)-saturated rCaM(1-75) (3B32.pdb) and rCaM(1-90) (3IFK.pdb) were determined, offering cautionary notes about the effect of packing interactions on flexible linkers. This chapter describes an array of methods for characterizing system-specific thermodynamic properties that in concert govern structure and function.
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Affiliation(s)
- Susan E O'Donnell
- Department of Biochemistry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
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22
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Borsi V, Luchinat C, Parigi G. Global and local mobility of apocalmodulin monitored through fast-field cycling relaxometry. Biophys J 2009; 97:1765-71. [PMID: 19751682 PMCID: PMC2749786 DOI: 10.1016/j.bpj.2009.07.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 06/27/2009] [Accepted: 07/08/2009] [Indexed: 02/03/2023] Open
Abstract
Calmodulin (CaM) is a ubiquitous eukaryotic protein with two conformationally independent domains that can bind up to two calcium ions each. In the calcium-bound state, CaM is able to regulate a vast number of cellular activities by binding to a multiplicity of target proteins in different modes. Its versatility has been ascribed to its anomalously high flexibility. The calcium-free form (apoCaM), which is the resting state of CaM in cells, is also able to functionally bind a number of protein targets, but its dynamics has received less attention. At variance with the calcium-bound form, the crystal structure of apoCaM shows a compact organization of the two domains, but NMR measurements could not detect any contact between them, thus indicating the presence of mobility in solution. The mobility of apoCaM is here investigated through protein proton relaxation rate measurements performed with a high-sensitivity fast-field cycling relaxometer. Such measurements provide direct access to the spectral density function and show that 1), the reorientation time is in agreement with a closed form of the protein; but 2), the collective order parameter is much smaller than for other well folded compact proteins, indicating that a remarkably large side-chain mobility must be present.
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Affiliation(s)
- Valentina Borsi
- Magnetic Resonance Center (CERM), University of Florence, Florence, Italy
| | - Claudio Luchinat
- Magnetic Resonance Center (CERM), University of Florence, Florence, Italy
- Department of Agricultural Biotechnology, University of Florence, Florence, Italy
| | - Giacomo Parigi
- Magnetic Resonance Center (CERM), University of Florence, Florence, Italy
- Department of Agricultural Biotechnology, University of Florence, Florence, Italy
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23
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Mukherjea M, Llinas P, Kim H, Travaglia M, Safer D, Ménétrey J, Franzini-Armstrong C, Selvin PR, Houdusse A, Sweeney HL. Myosin VI dimerization triggers an unfolding of a three-helix bundle in order to extend its reach. Mol Cell 2009; 35:305-15. [PMID: 19664948 DOI: 10.1016/j.molcel.2009.07.010] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Revised: 07/14/2009] [Accepted: 07/23/2009] [Indexed: 10/20/2022]
Abstract
Myosin VI challenges the prevailing theory of how myosin motors move on actin: the lever arm hypothesis. While the reverse directionality and large powerstroke of myosin VI can be attributed to unusual properties of a subdomain of the motor (converter with a unique insert), these adaptations cannot account for the large step size on actin. Either the lever arm hypothesis needs modification, or myosin VI has some unique form of extension of its lever arm. We determined the structure of the region immediately distal to the lever arm of the motor and show that it is a three-helix bundle. Based on C-terminal truncations that display the normal range of step sizes on actin, CD, fluorescence studies, and a partial deletion of the bundle, we demonstrate that this bundle unfolds upon dimerization of two myosin VI monomers. This unconventional mechanism generates an extension of the lever arm of myosin VI.
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Affiliation(s)
- Monalisa Mukherjea
- Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, 19104, USA
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24
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Xiao Q, Prussia A, Yu K, Cui YY, Hartzell HC. Regulation of bestrophin Cl channels by calcium: role of the C terminus. ACTA ACUST UNITED AC 2009; 132:681-92. [PMID: 19029375 PMCID: PMC2585866 DOI: 10.1085/jgp.200810056] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Human bestrophin-1 (hBest1), which is genetically linked to several kinds of retinopathy and macular degeneration in both humans and dogs, is the founding member of a family of Cl− ion channels that are activated by intracellular Ca2+. At present, the structures and mechanisms responsible for Ca2+ sensing remain unknown. Here, we have used a combination of molecular modeling, density functional–binding energy calculations, mutagenesis, and patch clamp to identify the regions of hBest1 involved in Ca2+ sensing. We identified a cluster of a five contiguous acidic amino acids in the C terminus immediately after the last transmembrane domain, followed by an EF hand and another regulatory domain that are essential for Ca2+ sensing by hBest1. The cluster of five amino acids (293–308) is crucial for normal channel gating by Ca2+ because all but two of the 35 mutations we made in this region rendered the channel incapable of being activated by Ca2+. Using homology models built on the crystal structure of calmodulin (CaM), an EF hand (EF1) was identified in hBest1. EF1 was predicted to bind Ca2+ with a slightly higher affinity than the third EF hand of CaM and lower affinity than the second EF hand of troponin C. As predicted by the model, the D312G mutation in the putative Ca2+-binding loop (312–323) reduced the apparent Ca2+ affinity by 20-fold. In addition, the D312G and D323N mutations abolished Ca2+-dependent rundown of the current. Furthermore, analysis of truncation mutants of hBest1 identified a domain adjacent to EF1 that is rich in acidic amino acids (350–390) that is required for Ca2+ activation and plays a role in current rundown. These experiments identify a region of hBest1 (312–323) that is involved in the gating of hBest1 by Ca2+ and suggest a model in which Ca2+ binding to EF1 activates the channel in a process that requires the acidic domain (293–308) and another regulatory domain (350–390). Many of the ∼100 disease-causing mutations in hBest1 are located in this region that we have implicated in Ca2+ sensing, suggesting that these mutations disrupt hBest1 channel gating by Ca2+.
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Affiliation(s)
- Qinghuan Xiao
- Department of Cell Biology and Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA 30322, USA
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25
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Lieto-Trivedi A, Coluccio LM. Calcium, nucleotide, and actin affect the interaction of mammalian Myo1c with its light chain calmodulin. Biochemistry 2008; 47:10218-26. [PMID: 18729383 DOI: 10.1021/bi8011059] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
To investigate the interaction of mammalian class I myosin, Myo1c, with its light chain calmodulin, we expressed (with calmodulin) truncation mutants consisting of the Myo1c motor domain followed by 0-4 presumed calmodulin-binding (IQ) domains (Myo1c (0IQ)-Myo1c (4IQ)). The amount of calmodulin associating with the Myo1c heavy chain increased with increasing number of IQ domains from Myo1c (0IQ) to Myo1c (3IQ). No calmodulin beyond that associated with Myo1c (3IQ) was found with Myo1c (4IQ) despite its availability, showing that Myo1c binds three molecules of calmodulin with no evidence of a fourth IQ domain. Unlike Myo1c (0IQ), the basal ATPase activity of Myo1c (1IQ) was >10-fold higher in Ca (2+) vs EGTA +/- exogenous calmodulin, showing that regulation is by Ca (2+) binding to calmodulin on the first IQ domain. The K m and V max of the actin-activated Mg (2+)-ATPase activity were largely independent of the number of IQ domains present and moderately affected by Ca (2+). In binding assays, some calmodulin pelleted with Myo1c heavy chain when actin was present, but a considerable fraction remained in the supernatant, suggesting that calmodulin is displaced most likely from the second IQ domain. The Myo1c heavy chain associated with actin in a nucleotide-dependent fashion. In ATP a smaller proportion of calmodulin pelleted with the heavy chain, suggesting that Myo1c undergoes nucleotide-dependent conformational changes that affect the affinity of calmodulin for the heavy chain. The studies support a model in which Myo1c in the inner ear is regulated by both Ca (2+) and nucleotide, which exert their effects on motor activity through the light-chain-binding region.
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Affiliation(s)
- Alena Lieto-Trivedi
- Boston Biomedical Research Institute, 64 Grove Street, Watertown, Massachusetts 02472, USA
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26
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Dieterich DC, Karpova A, Mikhaylova M, Zdobnova I, König I, Landwehr M, Kreutz M, Smalla KH, Richter K, Landgraf P, Reissner C, Boeckers TM, Zuschratter W, Spilker C, Seidenbecher CI, Garner CC, Gundelfinger ED, Kreutz MR. Caldendrin-Jacob: a protein liaison that couples NMDA receptor signalling to the nucleus. PLoS Biol 2008; 6:e34. [PMID: 18303947 PMCID: PMC2253627 DOI: 10.1371/journal.pbio.0060034] [Citation(s) in RCA: 154] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Accepted: 01/03/2008] [Indexed: 11/18/2022] Open
Abstract
NMDA (N-methyl-D-aspartate) receptors and calcium can exert multiple and very divergent effects within neuronal cells, thereby impacting opposing occurrences such as synaptic plasticity and neuronal degeneration. The neuronal Ca2+ sensor Caldendrin is a postsynaptic density component with high similarity to calmodulin. Jacob, a recently identified Caldendrin binding partner, is a novel protein abundantly expressed in limbic brain and cerebral cortex. Strictly depending upon activation of NMDA-type glutamate receptors, Jacob is recruited to neuronal nuclei, resulting in a rapid stripping of synaptic contacts and in a drastically altered morphology of the dendritic tree. Jacob's nuclear trafficking from distal dendrites crucially requires the classical Importin pathway. Caldendrin binds to Jacob's nuclear localization signal in a Ca2+-dependent manner, thereby controlling Jacob's extranuclear localization by competing with the binding of Importin-alpha to Jacob's nuclear localization signal. This competition requires sustained synapto-dendritic Ca2+ levels, which presumably cannot be achieved by activation of extrasynaptic NMDA receptors, but are confined to Ca2+ microdomains such as postsynaptic spines. Extrasynaptic NMDA receptors, as opposed to their synaptic counterparts, trigger the cAMP response element-binding protein (CREB) shut-off pathway, and cell death. We found that nuclear knockdown of Jacob prevents CREB shut-off after extrasynaptic NMDA receptor activation, whereas its nuclear overexpression induces CREB shut-off without NMDA receptor stimulation. Importantly, nuclear knockdown of Jacob attenuates NMDA-induced loss of synaptic contacts, and neuronal degeneration. This defines a novel mechanism of synapse-to-nucleus communication via a synaptic Ca2+-sensor protein, which links the activity of NMDA receptors to nuclear signalling events involved in modelling synapto-dendritic input and NMDA receptor-induced cellular degeneration.
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Affiliation(s)
- Daniela C Dieterich
- AG Molecular Mechanisms of Plasticity, Department of Neurochemistry and Molecular Biology, Leibniz-Institute for Neurobiology, Magdeburg, Germany
| | - Anna Karpova
- AG Molecular Mechanisms of Plasticity, Department of Neurochemistry and Molecular Biology, Leibniz-Institute for Neurobiology, Magdeburg, Germany
| | - Marina Mikhaylova
- AG Molecular Mechanisms of Plasticity, Department of Neurochemistry and Molecular Biology, Leibniz-Institute for Neurobiology, Magdeburg, Germany
| | - Irina Zdobnova
- AG Molecular Mechanisms of Plasticity, Department of Neurochemistry and Molecular Biology, Leibniz-Institute for Neurobiology, Magdeburg, Germany
| | - Imbritt König
- AG Molecular Mechanisms of Plasticity, Department of Neurochemistry and Molecular Biology, Leibniz-Institute for Neurobiology, Magdeburg, Germany
| | - Marco Landwehr
- AG Molecular Mechanisms of Plasticity, Department of Neurochemistry and Molecular Biology, Leibniz-Institute for Neurobiology, Magdeburg, Germany
| | - Martin Kreutz
- AG Molecular Mechanisms of Plasticity, Department of Neurochemistry and Molecular Biology, Leibniz-Institute for Neurobiology, Magdeburg, Germany
| | - Karl-Heinz Smalla
- AG Molecular Mechanisms of Plasticity, Department of Neurochemistry and Molecular Biology, Leibniz-Institute for Neurobiology, Magdeburg, Germany
| | - Karin Richter
- Institute for Medical Neurobiology, Otto-von-Guericke University, Magdeburg, Germany
| | - Peter Landgraf
- AG Molecular Mechanisms of Plasticity, Department of Neurochemistry and Molecular Biology, Leibniz-Institute for Neurobiology, Magdeburg, Germany
| | - Carsten Reissner
- AG Molecular Mechanisms of Plasticity, Department of Neurochemistry and Molecular Biology, Leibniz-Institute for Neurobiology, Magdeburg, Germany
| | - Tobias M Boeckers
- Institute for Anatomy and Cell Biology, University of Ulm, Ulm, Germany
| | - Werner Zuschratter
- AG Molecular Mechanisms of Plasticity, Department of Neurochemistry and Molecular Biology, Leibniz-Institute for Neurobiology, Magdeburg, Germany
| | - Christina Spilker
- AG Molecular Mechanisms of Plasticity, Department of Neurochemistry and Molecular Biology, Leibniz-Institute for Neurobiology, Magdeburg, Germany
| | - Constanze I Seidenbecher
- AG Molecular Mechanisms of Plasticity, Department of Neurochemistry and Molecular Biology, Leibniz-Institute for Neurobiology, Magdeburg, Germany
| | - Craig C Garner
- Department of Psychiatry and Behavioral Sciences, Nancy Pritzker Laboratory, Stanford University, Palo Alto, California, United States of America
| | - Eckart D Gundelfinger
- AG Molecular Mechanisms of Plasticity, Department of Neurochemistry and Molecular Biology, Leibniz-Institute for Neurobiology, Magdeburg, Germany
| | - Michael R Kreutz
- AG Molecular Mechanisms of Plasticity, Department of Neurochemistry and Molecular Biology, Leibniz-Institute for Neurobiology, Magdeburg, Germany
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Tang N, Lin T, Yang J, Foskett JK, Ostap EM. CIB1 and CaBP1 bind to the myo1c regulatory domain. J Muscle Res Cell Motil 2007; 28:285-91. [PMID: 17994197 PMCID: PMC2901637 DOI: 10.1007/s10974-007-9124-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Accepted: 10/25/2007] [Indexed: 01/08/2023]
Abstract
Myo1c is a member of the myosin-I family that binds phosphoinositides and links the actin cytoskeleton to cellular membranes. Recent investigations suggest that targeting of myo1c to some subcellular regions requires the binding of an unknown protein to the IQ motifs in the myo1c regulatory domain. We identify two myristoylated proteins that bind the myo1c regulatory domain: calcium-binding protein 1 (CaBP1) and calcium- and integrin-binding-protein-1 (CIB1). CIB1 and CaBP1 interact with myo1c in vivo as determined by pull-down experiments and fluorescence microscopy where the endogenously expressed proteins show extensive cellular colocalization with myo1c. CIB1 and CaBP1 bind to the myo1c IQ motifs in the regulatory domain where they compete with calmodulin for binding. CaBP1 has a higher apparent affinity for myo1c than CIB1, and both proteins better compete with calmodulin in the presence of calcium. We propose that these proteins may play a role in specifying subcellular localization of myo1c.
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Affiliation(s)
- Nanyun Tang
- The Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, 3700 Hamilton Walk, Philadelphia, PA 19104-6085, USA. Department of Physiology, University of Pennsylvania School of Medicine, B400 Richards Building, 3700 Hamilton Walk, Philadelphia, PA 19104-6085, USA
| | - Tianming Lin
- The Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, 3700 Hamilton Walk, Philadelphia, PA 19104-6085, USA. Department of Physiology, University of Pennsylvania School of Medicine, B400 Richards Building, 3700 Hamilton Walk, Philadelphia, PA 19104-6085, USA
| | - Jun Yang
- Department of Physiology, University of Pennsylvania School of Medicine, B400 Richards Building, 3700 Hamilton Walk, Philadelphia, PA 19104-6085, USA
| | - J. Kevin Foskett
- Department of Physiology, University of Pennsylvania School of Medicine, B400 Richards Building, 3700 Hamilton Walk, Philadelphia, PA 19104-6085, USA
| | - E. Michael Ostap
- The Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, 3700 Hamilton Walk, Philadelphia, PA 19104-6085, USA. Department of Physiology, University of Pennsylvania School of Medicine, B400 Richards Building, 3700 Hamilton Walk, Philadelphia, PA 19104-6085, USA
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28
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Manceva S, Lin T, Pham H, Lewis JH, Goldman YE, Ostap EM. Calcium regulation of calmodulin binding to and dissociation from the myo1c regulatory domain. Biochemistry 2007; 46:11718-26. [PMID: 17910470 PMCID: PMC2566900 DOI: 10.1021/bi700894h] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Myo1c is an unconventional myosin involved in cell signaling and membrane dynamics. Calcium binding to the regulatory-domain-associated calmodulin affects myo1c motor properties, but the kinetic details of this regulation are not fully understood. We performed actin gliding assays, ATPase measurements, fluorescence spectroscopy, and stopped-flow kinetics to determine the biochemical parameters that define the calmodulin-regulatory-domain interaction. We found calcium moderately increases the actin-activated ATPase activity and completely inhibits actin gliding. Addition of exogenous calmodulin in the presence of calcium fully restores the actin gliding rate. A fluorescently labeled calmodulin mutant (N111C) binds to recombinant peptides containing the myo1c IQ motifs at a diffusion-limited rate in the presence and absence of calcium. Measurements of calmodulin dissociation from the IQ motifs in the absence of calcium show that the calmodulin bound to the IQ motif adjacent to the motor domain (IQ1) has the slowest dissociation rate (0.0007 s-1), and the IQ motif adjacent to the tail domain (IQ3) has the fastest dissociation rate (0.5 s-1). When the complex is equilibrated with calcium, calmodulin dissociates most rapidly from IQ1 (60 s-1). However, this increased rate of dissociation is limited by a slow calcium-induced conformational change (3 s-1). Fluorescence anisotropy decay of fluorescently labeled N111C bound to myo1c did not depend appreciably on Ca2+. Our data suggest that the calmodulin bound to the IQ motif adjacent to the motor domain is rapidly exchangeable in the presence of calcium and is responsible for regulation of myo1c ATPase and motile activity.
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Affiliation(s)
| | | | | | | | | | - E. Michael Ostap
- *Corresponding author: E. Michael Ostap, Department of Physiology, University of Pennsylvania School of Medicine, B400 Richards Building, Philadelphia, PA 19104-6085, Phone: 215-573-9758, Fax: 215-573-1171,
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29
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Rainaldi M, Yamniuk AP, Murase T, Vogel HJ. Calcium-dependent and -independent binding of soybean calmodulin isoforms to the calmodulin binding domain of tobacco MAPK phosphatase-1. J Biol Chem 2007; 282:6031-42. [PMID: 17202149 DOI: 10.1074/jbc.m608970200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The recent finding of an interaction between calmodulin (CaM) and the tobacco mitogen-activated protein kinase phosphatase-1 (NtMKP1) establishes an important connection between Ca(2+) signaling and the MAPK cascade, two of the most important signaling pathways in plant cells. Here we have used different biophysical techniques, including fluorescence and NMR spectroscopy as well as microcalorimetry, to characterize the binding of soybean CaM isoforms, SCaM-1 and -4, to synthetic peptides derived from the CaM binding domain of NtMKP1. We find that the actual CaM binding region is shorter than what had previously been suggested. Moreover, the peptide binds to the SCaM C-terminal domain even in the absence of free Ca(2+) with the single Trp residue of the NtMKP1 peptides buried in a solvent-inaccessible hydrophobic region. In the presence of Ca(2+), the peptides bind first to the C-terminal lobe of the SCaMs with a nanomolar affinity, and at higher peptide concentrations, a second peptide binds to the N-terminal domain with lower affinity. Thermodynamic analysis demonstrates that the formation of the peptide-bound complex with the Ca(2+)-loaded SCaMs is driven by favorable binding enthalpy due to a combination of hydrophobic and electrostatic interactions. Experiments with CaM proteolytic fragments showed that the two domains bind the peptide in an independent manner. To our knowledge, this is the first report providing direct evidence for sequential binding of two identical peptides of a target protein to CaM. Discussion of the potential biological role of this interaction motif is also provided.
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Affiliation(s)
- Mario Rainaldi
- Structural Biology Research Group, Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
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30
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Lian LY, Myatt D, Kitmitto A. Apo calmodulin binding to the L-type voltage-gated calcium channel Cav1.2 IQ peptide. Biochem Biophys Res Commun 2007; 353:565-70. [PMID: 17189613 DOI: 10.1016/j.bbrc.2006.12.070] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Accepted: 12/07/2006] [Indexed: 11/26/2022]
Abstract
The influx of calcium through the L-type voltage-gated calcium channels (LTCCs) is the trigger for the process of calcium-induced calcium release (CICR) from the sarcoplasmic reticulum, an essential step for cardiac contraction. There are two feedback mechanisms that regulate LTCC activity: calcium-dependent inactivation (CDI) and calcium-dependent facilitation (CDF), both of which are mediated by calmodulin (CaM) binding. The IQ domain (aa 1645-1668) housed within the cytoplasmic domain of the LTCC Cav1.2 subunit has been shown to bind both calcium-loaded (Ca2+CaM ) and calcium-free CaM (apoCaM). Here, we provide new data for the structural basis for the interaction of apoCaM with the IQ peptide using NMR, revealing that the apoCaM C-lobe residues are most significantly perturbed upon complex formation. In addition, we have employed transmission electron microscopy of purified LTCC complexes which shows that both apoCaM and Ca2+CaM can bind to the intact channel.
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Affiliation(s)
- Lu-Yun Lian
- School of Biological Sciences, The University of Liverpool, P.O. Box 147, Liverpool L69 7ZB, UK.
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31
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Houdusse A, Gaucher JF, Krementsova E, Mui S, Trybus KM, Cohen C. Crystal structure of apo-calmodulin bound to the first two IQ motifs of myosin V reveals essential recognition features. Proc Natl Acad Sci U S A 2006; 103:19326-31. [PMID: 17151196 PMCID: PMC1687203 DOI: 10.1073/pnas.0609436103] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2006] [Indexed: 11/18/2022] Open
Abstract
A 2.5-A resolution structure of calcium-free calmodulin (CaM) bound to the first two IQ motifs of the murine myosin V heavy chain reveals an unusual CaM conformation. The C-terminal lobe of each CaM adopts a semi-open conformation that grips the first part of the IQ motif (IQxxxR), whereas the N-terminal lobe adopts a closed conformation that interacts more weakly with the second part of the motif (GxxxR). Variable residues in the IQ motif play a critical role in determining the precise structure of the bound CaM, such that even the consensus residues of different motifs show unique interactions with CaM. This complex serves as a model for the lever arm region of many classes of unconventional myosins, as well as other IQ motif-containing proteins such as neuromodulin and IQGAPs.
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Affiliation(s)
- Anne Houdusse
- *Motilité Structurale, Institut Curie, Centre National de la Recherche Scientifique, Unite Mixté de Recherche 144, 26 rue d'Ulm, 75248, Paris Cedex 05, France
| | - Jean-François Gaucher
- Université Paris Descartes/Centre National de la Recherche Scientifique, Faculté de Pharmacie, Laboratoire de Cristallographie et RMN Biologiques (Unite Mixté de Recherche 8015), 4 Avenue de l'Observatoire, 75270 Paris Cedex 06, France
| | - Elena Krementsova
- Department of Molecular Physiology and Biophysics, Health Sciences Research Facility, University of Vermont, Burlington, VT 05405-0068; and
| | - Suet Mui
- Rosenstiel Basic Medical Sciences Research Center, MS 029, Brandeis University, P.O. Box 549110, Waltham, MA 02454-9110
| | - Kathleen M. Trybus
- Department of Molecular Physiology and Biophysics, Health Sciences Research Facility, University of Vermont, Burlington, VT 05405-0068; and
| | - Carolyn Cohen
- Rosenstiel Basic Medical Sciences Research Center, MS 029, Brandeis University, P.O. Box 549110, Waltham, MA 02454-9110
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32
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Capozzi F, Casadei F, Luchinat C. EF-hand protein dynamics and evolution of calcium signal transduction: an NMR view. J Biol Inorg Chem 2006; 11:949-62. [PMID: 16957918 DOI: 10.1007/s00775-006-0163-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Accepted: 08/09/2006] [Indexed: 10/24/2022]
Abstract
Calcium signaling, one of the most widespread signaling mechanisms in cells, is generally carried out by EF-hand proteins, characterized by a helix-loop-helix motif paired in functional domains. EF-hand proteins may be viewed as molecular switches activated by calcium concentration transients. The EF-hand structural database has grown to a point where meaningful inferences on the functional conformational rearrangements upon calcium binding can be made by comparing a fair number of pairs of end points, i.e., the structures of the apo and calcium-bound forms. More compact descriptors of the movement associated with calcium binding, in terms of principal component analysis of the six interhelical angles, have also become available. Dynamic information obtained by NMR, also with the aid of calcium substitution with paramagnetic lanthanides, is shedding light on the intrinsic amplitude of the conformational degrees of freedom sampled by the various members of the EF-hand superfamily, as well as on the time scales of the motions. Particularly, NMR of lanthanide derivatives helps in capturing long time scale motions. Both static and dynamic pictures reveal a large variety of behaviors. It is increasingly recognized that the EF-hand machinery has differentiated its behavior during evolution in several ways, e.g., by modifying one of the loops, by undergoing a further duplication after the initial motif duplication that originated the functional domain, or by acquiring the ability to dimerize.
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Affiliation(s)
- Francesco Capozzi
- Department of Food Science, University of Bologna, Piazza G. Goidanich 60, 47023, Cesena, Italy
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33
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Debreczeni JE, Farkas L, Harmat V, Hetényi C, Hajdú I, Závodszky P, Kohama K, Nyitray L. Structural Evidence for Non-canonical Binding of Ca2+ to a Canonical EF-hand of a Conventional Myosin. J Biol Chem 2005; 280:41458-64. [PMID: 16227209 DOI: 10.1074/jbc.m506315200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously identified a single inhibitory Ca2+-binding site in the first EF-hand of the essential light chain of Physarum conventional myosin (Farkas, L., Malnasi-Csizmadia, A., Nakamura, A., Kohama, K., and Nyitray, L. (2003) J. Biol. Chem. 278, 27399-27405). As a general rule, conformation of the EF-hand-containing domains in the calmodulin family is "closed" in the absence and "open" in the presence of bound cations; a notable exception is the unusual Ca2+-bound closed domain in the essential light chain of the Ca2+-activated scallop muscle myosin. Here we have reported the 1.8 A resolution structure of the regulatory domain (RD) of Physarum myosin II in which Ca2+ is bound to a canonical EF-hand that is also in a closed state. The 12th position of the EF-hand loop, which normally provides a bidentate ligand for Ca2+ in the open state, is too far in the structure to participate in coordination of the ion. The structure includes a second Ca2+ that only mediates crystal contacts. To reveal the mechanism behind the regulatory effect of Ca2+, we compared conformational flexibilities of the liganded and unliganded RD. Our working hypothesis, i.e. the modulatory effect of Ca2+ on conformational flexibility of RD, is in line with the observed suppression of hydrogen-deuterium exchange rate in the Ca2+-bound form, as well as with results of molecular dynamics calculations. Based on this evidence, we concluded that Ca2+-induced change in structural dynamics of RD is a major factor in Ca2+-mediated regulation of Physarum myosin II activity.
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Affiliation(s)
- Judit E Debreczeni
- Department of Biochemistry, Eötvös Loránd University, Budapest H-1117, Hungary
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34
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Abstract
Myo1b is a widely expressed myosin-I isoform that concentrates on endosomal and ruffling membranes and is thought to play roles in membrane trafficking and dynamics. Myo1b is alternatively spliced within the regulatory domain of the molecule, yielding isoforms with six (myo1b(a)), five (myo1b(b)), or four (myo1b(c)) non-identical IQ motifs. The calmodulin binding properties of the myo1b IQ motifs have not been investigated, and the mechanical and cell biological consequences of alternative splicing are not known. Therefore, we expressed the alternatively spliced myo1b isoforms truncated after the final IQ motif and included a sequence at their C termini that is a substrate for bacterial biotin ligase. Site-specific biotinylation allows us to specifically attach the myosin to motility surfaces via a biotin-streptavidin linkage. We measured the ATPase and motile properties of the recombinant myo1b splice isoforms, and we correlated these properties with calmodulin binding. We confirmed that calcium-dependent changes in the ATPase activity are due to calcium binding to the calmodulin closest to the motor. We found that calmodulin binds tightly to some of the IQ motifs (Kd < 0.2 microM) and very weakly to the others (Kd > 5 microM), suggesting that a subset of the IQ motifs are not calmodulin bound under physiological conditions. Finally, we found the in vitro motility rate to be dependent on the myo1b isoform and the calmodulin concentration and that the myo1b regulatory domain acts as a rigid lever arm upon calmodulin binding to the high affinity and low affinity IQ motifs.
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Affiliation(s)
- Tianming Lin
- Department of Physiology and The Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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35
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Chevreux G, Potier N, Van Dorsselaer A, Bahloul A, Houdusse A, Wells A, Sweeney HL. Electrospray ionization mass spectrometry studies of noncovalent myosin VI complexes reveal a new specific calmodulin binding site. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2005; 16:1367-76. [PMID: 15979337 DOI: 10.1016/j.jasms.2005.03.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2005] [Revised: 03/21/2005] [Accepted: 03/22/2005] [Indexed: 05/03/2023]
Abstract
Among the myosin superfamily, myosin VI differs from all others by a reverse directionality and a particular motility. Little structural information is available for myosin VI. It is known that it binds one calmodulin (CaM) by means of a single "IQ motif" and that myosin VI contains a specific insert located at the junction between the motor domain (MD) and the lever arm, likely to play a critical role for the unusual motility previously observed. Electrospray ionization mass spectrometry (MS) was used to determine the CaM and Ca2+ stoichiometries in several myosin VI constructs. In particular, the experimental conditions required for the observation of multiprotein/Ca2+ noncovalent assemblies are detailed for two truncated MD constructs (less than 20 kDa) and for three full MD constructs (more than 90 KDa). The specificity of the detected stoichiometries is discussed for each construct and the resolving power of Time of Flight mass spectrometry is stressed, in particular for the detection of metal ions binding to high molecular weight complexes. MS reveals a new CaM binding site for myosin VI and highlights a different behavior for the five myosin VI constructs versus Ca2+ binding. In addition to these stoichiometry based experiments, gas-phase dissociation analyses on intact complexes are described. They reveal that Ca2+ transfer between protein partners occurs during the dissociation process for one construct with a full MD. Charge-transfer and dissociation behavior has allowed to draw structural assumptions for the interaction of the MD with the CaM N-terminal lobe.
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36
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Knight PJ, Thirumurugan K, Xu Y, Wang F, Kalverda AP, Stafford WF, Sellers JR, Peckham M. The predicted coiled-coil domain of myosin 10 forms a novel elongated domain that lengthens the head. J Biol Chem 2005; 280:34702-8. [PMID: 16030012 DOI: 10.1074/jbc.m504887200] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Myosin 10 contains a region of predicted coiled coil 120 residues long. However, the highly charged nature and pattern of charges in the proximal 36 residues appear incompatible with coiled-coil formation. Circular dichroism, NMR, and analytical ultracentrifugation show that a synthesized peptide containing this region forms a stable single alpha-helix (SAH) domain in solution and does not dimerize to form a coiled coil even at millimolar concentrations. Additionally, electron microscopy of a recombinant myosin 10 containing the motor, the three calmodulin binding domains, and the full-length predicted coiled coil showed that it was mostly monomeric at physiological protein concentration. In dimers the molecules were joined only at their extreme distal ends, and no coiled-coil tail was visible. Furthermore, the neck lengths of both monomers and dimers were much longer than expected from the number of calmodulin binding domains. In contrast, micrographs of myosin 5 heavy meromyosin obtained under the same conditions clearly showed a coiled-coil tail, and the necks were the predicted length. Thus the predicted coiled coil of myosin 10 forms a novel elongated structure in which the proximal region is a SAH domain and the distal region is a SAH domain (or has an unknown extended structure) that dimerizes only at its end. Sequence comparisons show that similar structures may exist in the predicted coiled-coil domains of myosins 6 and 7a and MyoM and could function to increase the size of the working stroke.
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Affiliation(s)
- Peter J Knight
- School of Biomedical Sciences, Astbury Centre for Structural Molecular Biology, and School of Biochemistry and Microbiology, University of Leeds, Leeds, LS2 9JT, United Kingdom
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37
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Köhler D, Struchholz S, Bähler M. The two IQ-motifs and Ca2+/calmodulin regulate the rat myosin 1d ATPase activity. FEBS J 2005; 272:2189-97. [PMID: 15853803 DOI: 10.1111/j.1742-4658.2005.04642.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The light chain binding domain of rat myosin 1d consists of two IQ-motifs, both of which bind the light chain calmodulin (CaM). To analyze the Myo1d ATPase activity as a function of the IQ-motifs and Ca2+/CaM binding, we expressed and affinity purified the Myo1d constructs Myo1d-head, Myo1d-IQ1, Myo1d-IQ1.2, Myo1d-IQ2 and Myo1dDeltaLV-IQ2. IQ1 exhibited a high affinity for CaM both in the absence and presence of free Ca2+. IQ2 had a lower affinity for CaM in the absence of Ca2+ than in the presence of Ca2+. The actin-activated ATPase activity of Myo1d was approximately 75% inhibited by Ca2+-binding to CaM. This inhibition was observed irrespective of whether IQ1, IQ2 or both IQ1 and IQ2 were fused to the head. Based on the measured Ca2+-dependence, we propose that Ca2+-binding to the C-terminal pair of high affinity sites in CaM inhibits the Myo1d actin-activated ATPase activity. This inhibition was due to a conformational change of the C-terminal lobe of CaM remaining bound to the IQ-motif(s). Interestingly, a similar but Ca2+-independent inhibition of Myo1d actin-activated ATPase activity was observed when IQ2, fused directly to the Myo1d-head, was rotated through 200 degrees by the deletion of two amino acids in the lever arm alpha-helix N-terminal to the IQ-motif.
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Affiliation(s)
- Danny Köhler
- Institute for General Zoology and Genetics, Westfälische Wilhelms University, Münster, Germany
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38
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Kouprina N, Pavlicek A, Collins NK, Nakano M, Noskov VN, Ohzeki JI, Mochida GH, Risinger JI, Goldsmith P, Gunsior M, Solomon G, Gersch W, Kim JH, Barrett JC, Walsh CA, Jurka J, Masumoto H, Larionov V. The microcephaly ASPM gene is expressed in proliferating tissues and encodes for a mitotic spindle protein. Hum Mol Genet 2005; 14:2155-65. [PMID: 15972725 DOI: 10.1093/hmg/ddi220] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The most common cause of primary autosomal recessive microcephaly (MCPH) appears to be mutations in the ASPM gene which is involved in the regulation of neurogenesis. The predicted gene product contains two putative N-terminal calponin-homology (CH) domains and a block of putative calmodulin-binding IQ domains common in actin binding cytoskeletal and signaling proteins. Previous studies in mouse suggest that ASPM is preferentially expressed in the developing brain. Our analyses reveal that ASPM is widely expressed in fetal and adult tissues and upregulated in malignant cells. Several alternatively spliced variants encoding putative ASPM isoforms with different numbers of IQ motifs were identified. The major ASPM transcript contains 81 IQ domains, most of which are organized into a higher order repeat (HOR) structure. Another prominent spliced form contains an in-frame deletion of exon 18 and encodes 14 IQ domains not organized into a HOR. This variant is conserved in mouse. Other spliced variants lacking both CH domains and a part of the IQ motifs were also detected, suggesting the existence of isoforms with potentially different functions. To elucidate the biochemical function of human ASPM, we developed peptide specific antibodies to the N- and C-termini of ASPM. In a western analysis of proteins from cultured human and mouse cells, the antibodies detected bands with mobilities corresponding to the predicted ASPM isoforms. Immunostaining of cultured human cells with antibodies revealed that ASPM is localized in the spindle poles during mitosis. This finding suggests that MCPH is the consequence of an impairment in mitotic spindle regulation in cortical progenitors due to mutations in ASPM.
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Affiliation(s)
- Natalay Kouprina
- Laboratory of Biosystems and Cancer, National Cancer Institute, Bethesda, MD 20892, USA
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39
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Somlyo AV, Khromov AS, Webb MR, Ferenczi MA, Trentham DR, He ZH, Sheng S, Shao Z, Somlyo AP. Smooth muscle myosin: regulation and properties. Philos Trans R Soc Lond B Biol Sci 2005; 359:1921-30. [PMID: 15647168 PMCID: PMC1693473 DOI: 10.1098/rstb.2004.1562] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The relationship of the biochemical states to the mechanical events in contraction of smooth muscle cross-bridges is reviewed. These studies use direct measurements of the kinetics of Pi and ADP release. The rate of release of Pi from thiophosphorylated cycling cross-bridges held isometric was biphasic with turnovers of 1.8 s-1 and 0.3 s-1, reflecting properties and forces directly acting on cross-bridges through mechanisms such as positive strain and inhibition by high-affinity MgADP binding. Fluorescent transients reporting release of an ADP analogue 3'-deac-edaADP were significantly faster in phasic than in tonic smooth muscles. Thiophosphorylation of myosin regulatory light chains (RLCs) increased and positive strain decreased the release rate around twofold. The rates of ADP release from rigor cross-bridges and the steady-state Pi release from cycling isometric cross-bridges are similar, indicating that the ADP-release step or an isomerization preceding it may limit the ATPase rate. Thus ADP release in phasic and tonic smooth muscles is a regulated step with strain- and dephosphorylation-dependence. High affinity of cross-bridges for ADP and slow ADP release prolong the fraction of the duty cycle occupied by strongly bound AM.ADP state(s) and contribute to the high economy of force that is characteristic of smooth muscle. RLC thiophosphorylation led to structural changes in smooth muscle cross-bridges consistent with our findings that thiophosphorylation and strain modulate product release.
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Affiliation(s)
- Avril V Somlyo
- Molecular Physiology and Biological Physics, University of Virginia, PO Box 800736, 1300 Jefferson Park Avenue, Charlottesville, VA 22908-0736, USA.
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40
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Jin H, Sha D, Wei J, Davis KM, Wu H, Jin Y, Wu JY. Effect of apocalmodulin on recombinant human brain glutamic acid decarboxylase. J Neurochem 2005; 92:739-48. [PMID: 15686475 DOI: 10.1111/j.1471-4159.2004.02901.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work, we report that the recombinant glutathione S-transferase (GST)-human L-glutamic acid decarboxylase (HGAD) isoforms, 65-kDa L-glutamic acid decarboxylase (GAD) (GST-HGAD65) fusion protein or free truncated HGAD65, were activated by apocalmodulin (ApoCaM) to an extent of 60%. Both truncated forms of GAD67 (tGAD67), HGAD67(Delta1-70) and HGAD67(Delta1-90), were markedly activated by ApoCaM to an extent of 141 and 85%, respectively, while GST-HGAD67 was not significantly affected. The activation appears to be due to an increase of GAD affinity for its cofactor, pyridoxal phosphate (PLP). This conclusion is based on the following observations. Firstly, the V(max) of GAD was increased when ApoCaM was present whereas the affinity for the substrate, glutamate, was not affected. Secondly, the affinity of GAD for PLP was increased in the presence of ApoCaM. Thirdly, results from calmodulin-agarose affinity column chromatography studies indicated a direct interaction or binding between ApoCaM and GAD. Fourthly, ApoCaM was found to be copurified with GAD65/GAD67 by anti-GAD65/67 immunoaffinity column using rat brain extract. Hence, it is proposed that a conformational change is induced when ApoCaM interacts with GAD65 or tGAD67, resulting in an increase of GAD affinity for PLP and the activation of GAD. The physiological significance of the interaction between GAD and ApoCaM is discussed.
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Affiliation(s)
- Hong Jin
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
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41
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Bhattacharya S, Bunick CG, Chazin WJ. Target selectivity in EF-hand calcium binding proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2004; 1742:69-79. [PMID: 15590057 DOI: 10.1016/j.bbamcr.2004.09.002] [Citation(s) in RCA: 185] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2004] [Revised: 08/30/2004] [Accepted: 09/01/2004] [Indexed: 10/26/2022]
Abstract
EF-hand calcium binding proteins have remarkable sequence homology and structural similarity, yet their response to binding of calcium is diverse and they function in a wide range of biological processes. Knowledge of the fine-tuning of EF-hand protein sequences to optimize specific biochemical properties has been significantly advanced over the past 10 years by determination of atomic resolution structures. These data lay the foundation for addressing how functional selectivity is generated from a generic ionic signal. This review presents current ideas about the structural mechanisms that provide the selectivity of different EF-hand proteins for specific cellular targets, using S100 and calmodulin family proteins to demonstrate the critical concepts. Three factors contribute significantly to target selectivity: molecular architecture, response to binding of Ca(2+) ions, and the characteristics of target binding surfaces. Comparisons of calmodulin and S100 proteins provide insights into the role these factors play in facilitating the variety of binding configurations necessary for recognizing a diverse set of targets.
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Affiliation(s)
- Shibani Bhattacharya
- Department of Biochemistry, Center for Structural Biology, 5140 BIOSCI/MRBIII, Vanderbilt University, Nashville, TN 37232-8725, USA
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42
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Martin SR, Bayley PM. Calmodulin bridging of IQ motifs in myosin-V. FEBS Lett 2004; 567:166-70. [PMID: 15178316 DOI: 10.1016/j.febslet.2004.04.053] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2004] [Revised: 04/14/2004] [Accepted: 04/23/2004] [Indexed: 11/18/2022]
Abstract
Ca(2+)-saturated calmodulin binds to double-length IQ lever-arm sequences from murine myosin-V, forming a 1:1 "bridging" complex with very high affinity, (K9d)<10 pM for double motifs, IQ34, IQ45 and IQ56). Such a 1:1 complex involves interaction of one calmodulin (CaM) molecule with two adjacent IQ-motifs, providing a molecular mechanism for the observed Ca(2+)-dependent CaM dissociation from the IQ-region. Structural considerations suggest that formation of the 1:1 complex requires a severe distortion of the lever-arm, potentially regulating functional motility. This would be consistent with a recent report of diverse, irregular shapes of the lever arm of myosin-V induced by the presence of Ca(2+).
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Affiliation(s)
- Stephen R Martin
- Division of Physical Biochemistry, National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
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43
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Seidenbecher CI, Landwehr M, Smalla KH, Kreutz M, Dieterich DC, Zuschratter W, Reissner C, Hammarback JA, Böckers TM, Gundelfinger ED, Kreutz MR. Caldendrin but not calmodulin binds to light chain 3 of MAP1A/B: an association with the microtubule cytoskeleton highlighting exclusive binding partners for neuronal Ca(2+)-sensor proteins. J Mol Biol 2004; 336:957-70. [PMID: 15095872 DOI: 10.1016/j.jmb.2003.12.054] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2003] [Revised: 12/15/2003] [Accepted: 12/18/2003] [Indexed: 11/19/2022]
Abstract
Caldendrin is a neuronal Ca(2+)-sensor protein (NCS), which represents the closest homologue of calmodulin (CaM) in nerve cells. It is tightly associated with the somato-dendritic cytoskeleton of neurons and highly enriched in the postsynaptic cytomatrix. Here, we report that caldendrin specifically associates with the microtubule cytoskeleton via an interaction with light chain 3 (LC3), a microtubule component with sequence homology to the GABAA receptor-associated protein (GABARAP), which is, like LC3, probably involved in cellular transport processes. Interestingly, two binding sites exist in LC3 for caldendrin from which only one exhibits a strict Ca(2+)-dependency for the interaction to take place but both require the presence of the first two EF-hands of caldendrin. CaM, however, is not capable of binding to LC3 at both sites despite its high degree of primary structure similarity with caldendrin. Computer modelling suggests that this might be explained by an altered distribution of surface charges at the first two EF-hands rendering each molecule, in principle, specific for a discrete set of binding partners. These findings provide molecular evidence that NCS can transduce signals to a specific target interaction irrespective of Ca(2+)-concentrations and CaM-levels.
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Affiliation(s)
- Constanze I Seidenbecher
- AG Molecular Mechanisms of Plasticity, Department of Neurochemistry/Molecular Biology, Leibniz Institute for Neurobiology, Brenneckestr. 6 39118 Magdeburg, Germany
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44
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Bahloul A, Chevreux G, Wells AL, Martin D, Nolt J, Yang Z, Chen LQ, Potier N, Van Dorsselaer A, Rosenfeld S, Houdusse A, Sweeney HL. The unique insert in myosin VI is a structural calcium-calmodulin binding site. Proc Natl Acad Sci U S A 2004; 101:4787-92. [PMID: 15037754 PMCID: PMC387326 DOI: 10.1073/pnas.0306892101] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Myosin VI contains an inserted sequence that is unique among myosin superfamily members and has been suggested to be a determinant of the reverse directionality and unusual motility of the motor. It is thought that each head of a two-headed myosin VI molecule binds one calmodulin (CaM) by means of a single "IQ motif". Using truncations of the myosin VI protein and electrospray ionization(ESI)-MS, we demonstrate that in fact each myosin VI head binds two CaMs. One CaM binds to a conventional IQ motif either with or without calcium and likely plays a regulatory role when calcium binds to its N-terminal lobe. The second CaM binds to a unique insertion between the converter region and IQ motif. This unusual CaM-binding site normally binds CaM with four Ca2+ and can bind only if the C-terminal lobe of CaM is occupied by calcium. Regions of the MD outside of the insert peptide contribute to the Ca(2+)-CaM binding, as truncations that eliminate elements of the MD alter CaM binding and allow calcium dissociation. We suggest that the Ca(2+)-CaM bound to the unique insert represents a structural CaM, and not a calcium sensor or regulatory component of the motor. This structure is likely an integral part of the myosin VI "converter" region and repositions the myosin VI "lever arm" to allow reverse direction (minus-end) motility on actin.
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Affiliation(s)
- Amel Bahloul
- Structural Motility, Institut Curie Centre National de la Recherche Scientifique, Unité Mixte de Recherche 144, 26 Rue d'Ulm, 75248 Paris 05, France
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45
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Abstract
Protein flexibility and rigidity can be analyzed using constraint theory, which views proteins as 3D networks of constraints involving covalent bonds and also including hydrophobic interactions and hydrogen bonds. This article describes an algorithm, ROCK (Rigidity Optimized Conformational Kinetics), which generates new conformations for these complex networks with many interlocked rings while maintaining the constraints. These new conformations are tracked for the flexible regions of a protein, while leaving the rigid regions undisturbed. An application to HIV protease demonstrates how large the flap motion can be. The algorithm is also used to generate conformational pathways between two distinct protein conformations. As an example, directed trajectories between the closed and the occluded conformations of the protein dihydrofolate reductase are determined.
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Affiliation(s)
- Ming Lei
- Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454, USA
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46
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Kilmartin JV. Sfi1p has conserved centrin-binding sites and an essential function in budding yeast spindle pole body duplication. ACTA ACUST UNITED AC 2003; 162:1211-21. [PMID: 14504268 PMCID: PMC2173958 DOI: 10.1083/jcb.200307064] [Citation(s) in RCA: 160] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Centrins are calmodulin-like proteins present in microtubule-organizing centers. The Saccharomyces cerevisiae centrin, Cdc31p, was functionally tagged with a single Z domain of protein A, and used in pull-down experiments to isolate Cdc31p-binding proteins. One of these, Sfi1p, localizes to the half-bridge of the spindle pole body (SPB), where Cdc31p is also localized. Temperature-sensitive mutants in SFI1 show a defect in SPB duplication and genetic interactions with cdc31-1. Sfi1p contains multiple internal repeats that are also present in a Schizosaccharomyces pombe protein, which also localizes to the SPB, and in several human proteins, one of which localizes close to the centriole region. Cdc31p binds directly to individual Sfi1 repeats in a 1:1 ratio, so a single molecule of Sfi1p binds multiple molecules of Cdc31p. The centrosomal human protein containing Sfi1 repeats also binds centrin in the repeat region, showing that this centrin-binding motif is conserved.
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47
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Farkas L, Malnasi-Csizmadia A, Nakamura A, Kohama K, Nyitray L. Localization and characterization of the inhibitory Ca2+-binding site of Physarum polycephalum myosin II. J Biol Chem 2003; 278:27399-405. [PMID: 12754206 DOI: 10.1074/jbc.m304220200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A myosin II is thought to be the driving force of the fast cytoplasmic streaming in the plasmodium of Physarum polycephalum. This regulated myosin, unique among conventional myosins, is inhibited by direct Ca2+ binding. Here we report that Ca2+ binds to the first EF-hand of the essential light chain (ELC) subunit of Physarum myosin. Flow dialysis experiments of wild-type and mutant light chains and the regulatory domain revealed a single binding site that shows moderate specificity for Ca2+. The regulatory light chain, in contrast to regulatory light chains of higher eukaryotes, is unable to bind divalent cations. Although the Ca2+-binding loop of ELC has a canonical sequence, replacement of glutamic acid to alanine in the -z coordinating position only slightly decreased the Ca2+ affinity of the site, suggesting that the Ca2+ coordination is different from classical EF-hands; namely, the specific "closed-to-open" conformational transition does not occur in the ELC in response to Ca2+. Ca2+- and Mg2+-dependent conformational changes in the microenvironment of the binding site were detected by fluorescence experiments. Transient kinetic experiments showed that the displacement of Mg2+ by Ca2+ is faster than the change in direction of cytoplasmic streaming; therefore, we conclude that Ca2+ inhibition could operate in physiological conditions. By comparing the Physarum Ca2+ site with the well studied Ca2+ switch of scallop myosin, we surmise that despite the opposite effect of Ca2+ binding on the motor activity, the two conventional myosins could have a common structural basis for Ca2+ regulation.
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Affiliation(s)
- Laszlo Farkas
- Department of Biochemistry, Eötvös Loránd University, Budapest 1117, Hungary
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48
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Abstract
A family of proteins known as IQGAPs have been identified in yeast, amebas and mammals. IQGAPs are multidomain molecules that contain several protein-interacting motifs which mediate binding to target proteins. Mammalian IQGAP1 is a component of signaling networks that are integral to maintaining cytoskeletal architecture and cell-cell adhesion. Published data suggest that IQGAP1 is a scaffolding protein that modulates cross-talk among diverse pathways in complex regulatory circuits. These pathways include modulating the actin cytoskeleton, mediating signaling by Rho family GTPases and calmodulin, regulating E-cadherin and beta-catenin function and organizing microtubules.
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Affiliation(s)
- Michael W Briggs
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Thorn 530, 75 Francis Street, Boston, MA 02115, USA
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49
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Bayley P, Martin S, Browne P, Royer C. Time-resolved fluorescence anisotropy studies show domain-specific interactions of calmodulin with IQ target sequences of myosin V. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2003; 32:122-7. [PMID: 12734700 DOI: 10.1007/s00249-002-0274-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Single cysteine mutants of calmodulin, Cam(S38C) and Cam(N111C), have been specifically labelled with Alexa488 maleimide to study the effects of calcium on the structural dynamics of calmodulin complexed with IQ3, IQ4 and IQ34 target peptide motifs of mouse unconventional myosin-V. Using phase fluorometry, the time-resolved anisotropy shows well-separated global and segmental correlation times. The calcium-sensitive global motion of either calmodulin domain can be independently monitored in domain-specific interactions of either apo- or Ca(4).calmodulin with IQ3 or IQ4 peptides. C-domain interactions predominate, and apo-N-domain interactions are unexpectedly weak. The 1:1 complex of Ca(4).calmodulin with IQ34 behaves as a compact globular species. The results demonstrate novel dynamic aspects of calmodulin-IQ interactions relating to the calcium regulation of motility of unconventional myosin.
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Affiliation(s)
- Peter Bayley
- Division of Physical Biochemistry, National Institute for Medical Research, Mill Hill, London, NW7 1AA, UK.
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50
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Cui Y, Wen J, Hung Sze K, Man D, Lin D, Liu M, Zhu G. Interaction between calcium-free calmodulin and IQ motif of neurogranin studied by nuclear magnetic resonance spectroscopy. Anal Biochem 2003; 315:175-82. [PMID: 12689827 DOI: 10.1016/s0003-2697(03)00007-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The interaction of Ca(2+)-free calmodulin (apoCaM) with the IQ motif corresponding to the calmodulin-binding domain of neurogranin has been studied by nuclear magnetic resonance (NMR) methods. The NMR spectra of uncomplexed apoCaM and apoCaM in complex with the IQ motif recorded at 750 MHz were studied and the backbone assignments of the protein in both forms were obtained by triple-resonance multidimensional NMR experiments. Chemical shift perturbations were used to map the binding surfaces. Only a single set of resonances was observed throughout the titration, indicating that the binding interaction is under fast exchange. Analysis of chemical shift changes indicates that (a) the main interaction and conformational changes occur in the C-terminal domain of calmodulin and (b) linker-1 (residues 40-44) between EF-1 and EF-2, linker-3 (residues 112-117) between EF-3 and EF-4, and the end of the alpha-helix H (residues 145-148) may be involved in the binding process. The dissociation constant (K(d)), estimated by fitting the chemical shift changes against the IQ peptide concentration, ranged from about 1.2 x 10(-5) to 8.8 x 10(-5) M. This result demonstrates that the interaction falls into the weak binding regime.
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Affiliation(s)
- Yanfang Cui
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, The Chinese Academy of Sciences, Wuhan 430071, People's Republic of China.
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