101
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Catazaro J, Andrews T, Milkovic NM, Lin J, Lowe AJ, Wilson MA, Powers R. 15N CEST data and traditional model-free analysis capture fast internal dynamics of DJ-1. Anal Biochem 2017; 542:24-28. [PMID: 29169778 DOI: 10.1016/j.ab.2017.11.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 10/24/2017] [Accepted: 11/18/2017] [Indexed: 11/24/2022]
Abstract
Previous studies have shown that relaxation parameters and fast protein dynamics can be quickly elucidated from 15N-CEST experiments [1]. Longitudinal R1 and transverse R2 values were reliably derived from fitting of CEST profiles. Herein we show that 15N-CEST experiments and traditional modelfree analysis provide the internal dynamics of three states of human protein DJ-1 at physiological temperature. The chemical exchange profiles show the absence of a minor state conformation and, in conjunction with 1H-15N NOEs, show increased mobility. R1 and R2 values remained relatively unchanged at the three naturally occurring oxidation states of DJ-1, but exhibit striking NOE differences. The NOE data was, therefore, essential in determining the internal motions of the DJ-1 proteins. To the authors' knowledge, we present the first study that combines 15N CEST data with traditional model-free analyses in the study of a biological system and affirm that more 'lean' model-free approaches should be used cautiously.
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Affiliation(s)
- Jonathan Catazaro
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - Tessa Andrews
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - Nicole M Milkovic
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0664, USA
| | - Jiusheng Lin
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0664, USA
| | - Austin J Lowe
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - Mark A Wilson
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0664, USA
| | - Robert Powers
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA; Nebraska Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA.
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102
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Binding kinetics and substrate selectivity in HIV-1 protease-Gag interactions probed at atomic resolution by chemical exchange NMR. Proc Natl Acad Sci U S A 2017; 114:E9855-E9862. [PMID: 29087351 DOI: 10.1073/pnas.1716098114] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The conversion of immature noninfectious HIV-1 particles to infectious virions is dependent upon the sequential cleavage of the precursor group-specific antigen (Gag) polyprotein by HIV-1 protease. The precise mechanism whereby protease recognizes distinct Gag cleavage sites, located in the intrinsically disordered linkers connecting the globular domains of Gag, remains unclear. Here, we probe the dynamics of the interaction of large fragments of Gag and various variants of protease (including a drug resistant construct) using Carr-Purcell-Meiboom-Gill relaxation dispersion and chemical exchange saturation transfer NMR experiments. We show that the conformational dynamics within the flaps of HIV-1 protease that form the lid over the catalytic cleft play a significant role in substrate specificity and ordered Gag processing. Rapid interconversion between closed and open protease flap conformations facilitates the formation of a transient, sparsely populated productive complex between protease and Gag substrates. Flap closure traps the Gag cleavage sites within the catalytic cleft of protease. Modulation of flap opening through protease-Gag interactions fine-tunes the lifetime of the productive complex and hence the likelihood of Gag proteolysis. A productive complex can also be formed in the presence of a noncognate substrate but is short-lived owing to lack of optimal complementarity between the active site cleft of protease and the substrate, resulting in rapid flap opening and substrate release, thereby allowing protease to differentiate between cognate and noncognate substrates.
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103
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VanSchouwen B, Ahmed R, Milojevic J, Melacini G. Functional dynamics in cyclic nucleotide signaling and amyloid inhibition. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:1529-1543. [PMID: 28911813 DOI: 10.1016/j.bbapap.2017.09.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 08/29/2017] [Accepted: 09/07/2017] [Indexed: 12/28/2022]
Abstract
It is now established that understanding the molecular basis of biological function requires atomic resolution maps of both structure and dynamics. Here, we review several illustrative examples of functional dynamics selected from our work on cyclic nucleotide signaling and amyloid inhibition. Although fundamentally diverse, a central aspect common to both fields is that function can only be rationalized by considering dynamic equilibria between distinct states of the accessible free energy landscape. The dynamic exchange between ground and excited states of signaling proteins is essential to explain auto-inhibition and allosteric activation. The dynamic exchange between non-toxic monomeric species and toxic oligomers of amyloidogenic proteins provides a foundation to understand amyloid inhibition. NMR ideally probes both types of dynamic exchange at atomic resolution. Specifically, we will show how NMR was utilized to reveal the dynamical basis of cyclic nucleotide affinity, selectivity, agonism and antagonism in multiple eukaryotic cAMP and cGMP receptors. We will also illustrate how NMR revealed the mechanism of action of plasma proteins that act as extracellular chaperones and inhibit the self-association of the prototypical amyloidogenic Aβ peptide. The examples outlined in this review illustrate the widespread implications of functional dynamics and the power of NMR as an indispensable tool in molecular pharmacology and pathology.
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Affiliation(s)
- Bryan VanSchouwen
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada
| | - Rashik Ahmed
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Julijana Milojevic
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada
| | - Giuseppe Melacini
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.
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104
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Ahmed R, VanSchouwen B, Jafari N, Ni X, Ortega J, Melacini G. Molecular Mechanism for the (-)-Epigallocatechin Gallate-Induced Toxic to Nontoxic Remodeling of Aβ Oligomers. J Am Chem Soc 2017; 139:13720-13734. [PMID: 28841302 DOI: 10.1021/jacs.7b05012] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
(-)-Epigallocatechin gallate (EGCG) effectively reduces the cytotoxicity of the Alzheimer's disease β-amyloid peptide (Aβ) by remodeling seeding-competent Aβ oligomers into off-pathway seeding-incompetent Aβ assemblies. However, the mechanism of EGCG-induced remodeling is not fully understood. Here we combine 15N and 1H dark-state exchange saturation transfer (DEST), relaxation, and chemical shift projection NMR analyses with fluorescence, dynamic light scattering, and electron microscopy to elucidate how EGCG remodels Aβ oligomers. We show that the remodeling adheres to a Hill-Scatchard model whereby the Aβ(1-40) self-association occurs cooperatively and generates Aβ(1-40) oligomers with multiple independent binding sites for EGCG with a Kd ∼10-fold lower than that for the Aβ(1-40) monomers. Upon binding to EGCG, the Aβ(1-40) oligomers become less solvent exposed, and the β-regions, which are involved in direct monomer-protofibril contacts in the absence of EGCG, undergo a direct-to-tethered contact shift. This switch toward less engaged monomer-protofibril contacts explains the seeding incompetency observed upon EGCG remodeling and suggests that EGCG interferes with secondary nucleation events known to generate toxic Aβ assemblies. Unexpectedly, the N-terminal residues experience an opposite EGCG-induced shift from tethered to direct contacts, explaining why EGCG remodeling occurs without release of Aβ(1-40) monomers. We also show that upon binding Aβ(1-40) oligomers the relative positions of the EGCG B and D rings change with respect to that of ring A. These distinct structural changes occurring in both Aβ(1-40) oligomers and EGCG during remodeling offer a foundation for understanding the molecular mechanism of EGCG as a neurotoxicity inhibitor. Furthermore, the results reported here illustrate the effectiveness of DEST-based NMR approaches in investigating the mechanism of low-molecular-weight amyloid inhibitors.
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Affiliation(s)
- Rashik Ahmed
- Department of Biochemistry and Biomedical Sciences and ‡Department of Chemistry and Chemical Biology, McMaster University , 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
| | - Bryan VanSchouwen
- Department of Biochemistry and Biomedical Sciences and ‡Department of Chemistry and Chemical Biology, McMaster University , 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
| | - Naeimeh Jafari
- Department of Biochemistry and Biomedical Sciences and ‡Department of Chemistry and Chemical Biology, McMaster University , 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
| | - Xiaodan Ni
- Department of Biochemistry and Biomedical Sciences and ‡Department of Chemistry and Chemical Biology, McMaster University , 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
| | - Joaquin Ortega
- Department of Biochemistry and Biomedical Sciences and ‡Department of Chemistry and Chemical Biology, McMaster University , 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
| | - Giuseppe Melacini
- Department of Biochemistry and Biomedical Sciences and ‡Department of Chemistry and Chemical Biology, McMaster University , 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
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105
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Wang H, Wang S, Li C, Li H, Mao Y, Liu W, Xu C, Long D. Probing Transient Release of Membrane-Sequestered Tyrosine-Based Signaling Motif by Solution NMR Spectroscopy. J Phys Chem Lett 2017; 8:3765-3769. [PMID: 28762742 DOI: 10.1021/acs.jpclett.7b01662] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Membrane sequestration of tyrosine-based signaling motifs of antigen receptors effectively restricts the signaling activities in resting lymphocytes. However, low level of basal signaling in resting cells is required for lymphocyte survival and antigen responsiveness, of which the molecular mechanism remains obscure. Here we probe the transient release of the cytoplasmic domain of the membrane-bound IgG heavy chain (mIgG-tail) by hydrogen exchange NMR spectroscopy, illustrating a dynamic molecular basis for its basal signaling activity. To solve the severe resonance overlap problem in the 2D spectra of mIgG-tail, a non-uniformly sampled pseudo-4D hydrogen exchange NMR experiment has been exploited to quantitatively measure site-specific hydrogen exchange rates. Our solution NMR study reveals transient solvent exposure of the ITT signaling motif that can be further enhanced by calcium ion, and provides insight into the mechanism of lymphocyte basal signaling.
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Affiliation(s)
- Hui Wang
- Hefei National Laboratory for Physical Sciences at the Microscale & School of Life Sciences, University of Science and Technology of China , 443 Huangshan Street, Hefei 230027, China
| | - Shengli Wang
- Hefei National Laboratory for Physical Sciences at the Microscale & School of Life Sciences, University of Science and Technology of China , 443 Huangshan Street, Hefei 230027, China
| | - Changting Li
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences , Shanghai 200031, China
| | - Hua Li
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences , Shanghai 200031, China
| | - Yunyun Mao
- Hefei National Laboratory for Physical Sciences at the Microscale & School of Life Sciences, University of Science and Technology of China , 443 Huangshan Street, Hefei 230027, China
| | - Wanli Liu
- School of Life Sciences, Tsinghua University , Beijing 100084, China
| | - Chenqi Xu
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences , Shanghai 200031, China
| | - Dong Long
- Hefei National Laboratory for Physical Sciences at the Microscale & School of Life Sciences, University of Science and Technology of China , 443 Huangshan Street, Hefei 230027, China
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106
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Jiang Y, Kalodimos CG. NMR Studies of Large Proteins. J Mol Biol 2017; 429:2667-2676. [PMID: 28728982 DOI: 10.1016/j.jmb.2017.07.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 07/06/2017] [Accepted: 07/06/2017] [Indexed: 01/08/2023]
Abstract
Recent breakthroughs in isotope-labeling and pulse sequence techniques have enabled the NMR characterization of large protein systems with molecular masses of hundreds of kilodaltons. NMR studies of a great variety of large proteins have provided unique insights into the binding, dynamic, and allosteric mechanisms. Here we present a brief summary of these developments by highlighting few cases that exemplify the uniqueness of NMR in providing atomic resolution information into key dynamic processes and structures of protein complexes with high degree of flexibility.
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Affiliation(s)
- Yajun Jiang
- Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, Minneapolis, MN 55455, United States; Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, United States
| | - Charalampos G Kalodimos
- Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, Minneapolis, MN 55455, United States; Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, United States.
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