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Nde J, Zhang P, Waxham MN, Cheung MS. Experiment and Simulation Reveal Residue Details for How Target Binding Tunes Calmodulin's Calcium-Binding Properties. J Phys Chem B 2023; 127:2900-2908. [PMID: 36977372 DOI: 10.1021/acs.jpcb.2c08734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
We aim to elucidate the molecular mechanism of the reciprocal relation of calmodulin's (CaM) target binding and its affinity for calcium ions (Ca2+), which is central to decoding CaM-dependent Ca2+ signaling in a cell. We employed stopped-flow experiments and coarse-grained molecular simulations that learn the coordination chemistry of Ca2+ in CaM from first-principle calculations. The associative memories as part of the coarse-grained force fields built on known protein structures further influence CaM's selection of its polymorphic target peptides in the simulations. We modeled the peptides from the Ca2+/CaM-binding domain of Ca2+/CaM-dependent kinase II (CaMKII), CaMKIIp (293-310) and selected distinctive mutations at the N-terminus. Our stopped-flow experiments have shown that the CaM's affinity for Ca2+ in the bound complex of Ca2+/CaM/CaMKIIp decreased significantly when Ca2+/CaM bound to the mutant peptide (296-AAA-298) compared to that bound to the wild-type peptide (296-RRK-298). The coarse-grained molecular simulations revealed that the 296-AAA-298 mutant peptide destabilized the structures of Ca2+-binding loops at the C-domain of CaM (c-CaM) due to both loss of electrostatic interactions and differences in polymorphic structures. We have leveraged a powerful coarse-grained approach to advance a residue-level understanding of the reciprocal relation in CaM, that could not be possibly achieved by other computational approaches.
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Affiliation(s)
- Jules Nde
- Department of Physics, University of Washington, Seattle, Washington 98105, United States
| | - Pengzhi Zhang
- Center for Bioinformatics and Computational Biology, Houston Methodist Research Institute, Houston, Texas 77030, United States
| | - M Neal Waxham
- Department of Neurobiology and Anatomy, University of Texas Health Science Center, Houston, Texas 77030, United States
| | - Margaret S Cheung
- Department of Physics, University of Washington, Seattle, Washington 98105, United States
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
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Nde J, Zhang P, Ezerski JC, Lu W, Knapp K, Wolynes PG, Cheung MS. Coarse-Grained Modeling and Molecular Dynamics Simulations of Ca 2+-Calmodulin. Front Mol Biosci 2021; 8:661322. [PMID: 34504868 PMCID: PMC8421859 DOI: 10.3389/fmolb.2021.661322] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 07/21/2021] [Indexed: 12/21/2022] Open
Abstract
Calmodulin (CaM) is a calcium-binding protein that transduces signals to downstream proteins through target binding upon calcium binding in a time-dependent manner. Understanding the target binding process that tunes CaM’s affinity for the calcium ions (Ca2+), or vice versa, may provide insight into how Ca2+-CaM selects its target binding proteins. However, modeling of Ca2+-CaM in molecular simulations is challenging because of the gross structural changes in its central linker regions while the two lobes are relatively rigid due to tight binding of the Ca2+ to the calcium-binding loops where the loop forms a pentagonal bipyramidal coordination geometry with Ca2+. This feature that underlies the reciprocal relation between Ca2+ binding and target binding of CaM, however, has yet to be considered in the structural modeling. Here, we presented a coarse-grained model based on the Associative memory, Water mediated, Structure, and Energy Model (AWSEM) protein force field, to investigate the salient features of CaM. Particularly, we optimized the force field of CaM and that of Ca2+ ions by using its coordination chemistry in the calcium-binding loops to match with experimental observations. We presented a “community model” of CaM that is capable of sampling various conformations of CaM, incorporating various calcium-binding states, and carrying the memory of binding with various targets, which sets the foundation of the reciprocal relation of target binding and Ca2+ binding in future studies.
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Affiliation(s)
- Jules Nde
- Department of Physics, University of Houston, Houston, TX, United States.,Center for Theoretical Biological Physics, Rice University, Houston, TX, United States
| | - Pengzhi Zhang
- Department of Physics, University of Houston, Houston, TX, United States
| | - Jacob C Ezerski
- Department of Physics, University of Houston, Houston, TX, United States
| | - Wei Lu
- Center for Theoretical Biological Physics, Rice University, Houston, TX, United States
| | - Kaitlin Knapp
- Center for Theoretical Biological Physics, Rice University, Houston, TX, United States
| | - Peter G Wolynes
- Center for Theoretical Biological Physics, Rice University, Houston, TX, United States
| | - Margaret S Cheung
- Department of Physics, University of Houston, Houston, TX, United States.,Center for Theoretical Biological Physics, Rice University, Houston, TX, United States
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Zhu W, Kong J, Zhang J, Wang J, Li W, Wang W. Consequences of Hydrophobic Nanotube Binding on the Functional Dynamics of Signaling Protein Calmodulin. ACS OMEGA 2019; 4:10494-10501. [PMID: 31460146 PMCID: PMC6648716 DOI: 10.1021/acsomega.9b01217] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Accepted: 06/06/2019] [Indexed: 06/10/2023]
Abstract
The wide applications of nanomaterials in industry and our daily life have raised growing concerns on their toxicity to human body. Increasing evidence links the cytotoxicity of nanoparticles to the disruption of cellular signaling pathways. Here, we report a computational study on the mechanisms of the cytotoxicity of carbon nanotubes (CNTs) by investigating the direct impacts of CNTs on the functional motions of calmodulin (CaM), which is one of the most important signaling proteins in a cell, and its signaling function relies on the Ca2+ binding-coupled conformational switching. Computational simulations with a coarse-grained model showed that binding of CNTs modifies the conformational equilibrium of CaM and induces the closed-to-open conformational transition, leading to the loss of its Ca2+-sensing ability. In addition, the binding of CNTs drastically increases the calcium affinity of CaM, which may disrupt the Ca2+ homeostasis in a cell. These results suggest that the binding of hydrophobic nanotubes not only inhibits the signaling function of CaM as a calcium sensor but also renders CaM to toxic species through sequestering Ca2+ from other competing calcium-binding proteins, suggesting a new physical mechanism of the cytotoxicity of nanoparticles.
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Affiliation(s)
- Wentao Zhu
- National Laboratory of Solid State
Microstructure, and Collaborative Innovation Center of Advanced Microstructures
and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Jianyang Kong
- National Laboratory of Solid State
Microstructure, and Collaborative Innovation Center of Advanced Microstructures
and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Jian Zhang
- National Laboratory of Solid State
Microstructure, and Collaborative Innovation Center of Advanced Microstructures
and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Jun Wang
- National Laboratory of Solid State
Microstructure, and Collaborative Innovation Center of Advanced Microstructures
and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Wenfei Li
- National Laboratory of Solid State
Microstructure, and Collaborative Innovation Center of Advanced Microstructures
and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Wei Wang
- National Laboratory of Solid State
Microstructure, and Collaborative Innovation Center of Advanced Microstructures
and Department of Physics, Nanjing University, Nanjing 210093, China
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Schaefer C, de Bruijn RAJ, McLeish TCB. Ligand-regulated oligomerisation of allosterically interacting proteins. SOFT MATTER 2018; 14:6961-6968. [PMID: 30009315 DOI: 10.1039/c8sm00943k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The binding of ligands to distinct sites at proteins or at protein clusters is often cooperative or anti-cooperative due to allosteric signalling between those sites. The allostery is usually attributed to a configurational change of the proteins from a relaxed to a configurationally different tense state. Alternatively, as originally proposed by Cooper and Dryden, a tense state may be achieved by merely restricting the thermal vibrations of the protein around its mean configuration. In this work, we provide theoretical tools to investigate fluctuation allostery using cooling and titration experiments in which ligands regulate dimerisation, or ring or chain formation. We discuss in detail how ligands may regulate the supramolecular (co)polymerisation of liganded and unliganded proteins.
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Affiliation(s)
- Charley Schaefer
- Department of Physics, Durham University, South Road, Durham, DH1 3LE, UK.
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El Hage K, Mondal P, Meuwly M. Free energy simulations for protein ligand binding and stability. MOLECULAR SIMULATION 2018. [DOI: 10.1080/08927022.2017.1416115] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Krystel El Hage
- Department of Chemistry, University of Basel , Basel, Switzerland
| | - Padmabati Mondal
- Department of Chemistry, University of Basel , Basel, Switzerland
| | - Markus Meuwly
- Department of Chemistry, University of Basel , Basel, Switzerland
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Xiao Y, Shaw GS, Konermann L. Calcium-Mediated Control of S100 Proteins: Allosteric Communication via an Agitator/Signal Blocking Mechanism. J Am Chem Soc 2017; 139:11460-11470. [PMID: 28758397 DOI: 10.1021/jacs.7b04380] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Allosteric proteins possess dynamically coupled residues for the propagation of input signals to distant target binding sites. The input signals usually correspond to "effector is present" or "effector is not present". Many aspects of allosteric regulation remain incompletely understood. This work focused on S100A11, a dimeric EF-hand protein with two hydrophobic target binding sites. An annexin peptide (Ax) served as the target. Target binding is allosterically controlled by Ca2+ over a distance of ∼26 Å. Ca2+ promotes formation of a [Ca4 S100 Ax2] complex, where the Ax peptides are accommodated between helices III/IV and III'/IV'. Without Ca2+ these binding sites are closed, precluding interactions with Ax. The allosteric mechanism was probed by microsecond MD simulations in explicit water, complemented by hydrogen exchange mass spectrometry (HDX/MS). Consistent with experimental data, MD runs in the absence of Ca2+ and Ax culminated in target binding site closure. In simulations on [Ca4 S100] the target binding sites remained open. These results capture the essence of allosteric control, revealing how Ca2+ prevents binding site closure. Both HDX/MS and MD data showed that the metalation sites become more dynamic after Ca2+ loss. However, these enhanced dynamics do not represent the primary trigger of the allosteric cascade. Instead, a labile salt bridge acts as an incessantly active "agitator" that destabilizes the packing of adjacent residues, causing a domino chain of events that culminates in target binding site closure. This agitator represents the starting point of the allosteric signal propagation pathway. Ca2+ binding rigidifies elements along this pathway, thereby blocking signal transmission. This blocking mechanism does not conform to the commonly held view that allosteric communication pathways generally originate at the sites where effectors interact with the protein.
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Affiliation(s)
- Yiming Xiao
- Department of Chemistry, The University of Western Ontario , London, Ontario N6A 5B7, Canada
| | - Gary S Shaw
- Department of Chemistry, The University of Western Ontario , London, Ontario N6A 5B7, Canada
| | - Lars Konermann
- Department of Chemistry, The University of Western Ontario , London, Ontario N6A 5B7, Canada
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Molecular mechanism of multispecific recognition of Calmodulin through conformational changes. Proc Natl Acad Sci U S A 2017; 114:E3927-E3934. [PMID: 28461506 DOI: 10.1073/pnas.1615949114] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Calmodulin (CaM) is found to have the capability to bind multiple targets. Investigations on the association mechanism of CaM to its targets are crucial for understanding protein-protein binding and recognition. Here, we developed a structure-based model to explore the binding process between CaM and skMLCK binding peptide. We found the cooperation between nonnative electrostatic interaction and nonnative hydrophobic interaction plays an important role in nonspecific recognition between CaM and its target. We also found that the conserved hydrophobic anchors of skMLCK and binding patches of CaM are crucial for the transition from high affinity to high specificity. Furthermore, this association process involves simultaneously both local conformational change of CaM and global conformational changes of the skMLCK binding peptide. We found a landscape with a mixture of the atypical "induced fit," the atypical "conformational selection," and "simultaneously binding-folding," depending on the synchronization of folding and binding. Finally, we extend our discussions on multispecific binding between CaM and its targets. These association characteristics proposed for CaM and skMLCK can provide insights into multispecific binding of CaM.
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Nandigrami P, Portman JJ. Comparing allosteric transitions in the domains of calmodulin through coarse-grained simulations. J Chem Phys 2016; 144:105102. [PMID: 26979706 DOI: 10.1063/1.4943130] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Calmodulin (CaM) is a ubiquitous Ca(2+)-binding protein consisting of two structurally similar domains with distinct stabilities, binding affinities, and flexibilities. We present coarse grained simulations that suggest that the mechanism for the domain's allosteric transitions between the open and closed conformations depends on subtle differences in the folded state topology of the two domains. Throughout a wide temperature range, the simulated transition mechanism of the N-terminal domain (nCaM) follows a two-state transition mechanism while domain opening in the C-terminal domain (cCaM) involves unfolding and refolding of the tertiary structure. The appearance of the unfolded intermediate occurs at a higher temperature in nCaM than it does in cCaM consistent with nCaM's higher thermal stability. Under approximate physiological conditions, the simulated unfolded state population of cCaM accounts for 10% of the population with nearly all of the sampled transitions (approximately 95%) unfolding and refolding during the conformational change. Transient unfolding significantly slows the domain opening and closing rates of cCaM, which can potentially influence its Ca(2+)-binding mechanism.
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Affiliation(s)
| | - John J Portman
- Department of Physics, Kent State University, Kent, Ohio 44242, USA
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