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Smith N, Dasgupta M, Wych DC, Dolamore C, Sierra RG, Lisova S, Marchany-Rivera D, Cohen AE, Boutet S, Hunter MS, Kupitz C, Poitevin F, Moss FR, Mittan-Moreau DW, Brewster AS, Sauter NK, Young ID, Wolff AM, Tiwari VK, Kumar N, Berkowitz DB, Hadt RG, Thompson MC, Follmer AH, Wall ME, Wilson MA. Changes in an enzyme ensemble during catalysis observed by high-resolution XFEL crystallography. Sci Adv 2024; 10:eadk7201. [PMID: 38536910 PMCID: PMC10971408 DOI: 10.1126/sciadv.adk7201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 02/21/2024] [Indexed: 04/01/2024]
Abstract
Enzymes populate ensembles of structures necessary for catalysis that are difficult to experimentally characterize. We use time-resolved mix-and-inject serial crystallography at an x-ray free electron laser to observe catalysis in a designed mutant isocyanide hydratase (ICH) enzyme that enhances sampling of important minor conformations. The active site exists in a mixture of conformations, and formation of the thioimidate intermediate selects for catalytically competent substates. The influence of cysteine ionization on the ICH ensemble is validated by determining structures of the enzyme at multiple pH values. Large molecular dynamics simulations in crystallo and time-resolved electron density maps show that Asp17 ionizes during catalysis and causes conformational changes that propagate across the dimer, permitting water to enter the active site for intermediate hydrolysis. ICH exhibits a tight coupling between ionization of active site residues and catalysis-activated protein motions, exemplifying a mechanism of electrostatic control of enzyme dynamics.
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Affiliation(s)
- Nathan Smith
- Department of Biochemistry and Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Medhanjali Dasgupta
- Department of Biochemistry and Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - David C. Wych
- Computer, Computational, and Statistical Sciences Division, Los Alamos National Laboratory, Los Alamos, NM 875405, USA
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Cole Dolamore
- Department of Biochemistry and Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Raymond G. Sierra
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Stella Lisova
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Darya Marchany-Rivera
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Aina E. Cohen
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Sébastien Boutet
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Mark S. Hunter
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Christopher Kupitz
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Frédéric Poitevin
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Frank R. Moss
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - David W. Mittan-Moreau
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Aaron S. Brewster
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Nicholas K. Sauter
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Iris D. Young
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Alexander M. Wolff
- Department of Chemistry and Biochemistry, University of California, Merced, CA 95340, USA
| | - Virendra K. Tiwari
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Nivesh Kumar
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - David B. Berkowitz
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Ryan G. Hadt
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Michael C. Thompson
- Department of Chemistry and Biochemistry, University of California, Merced, CA 95340, USA
| | - Alec H. Follmer
- Department of Chemistry, University of California-Irvine, Irvine, CA 92697, USA
| | - Michael E. Wall
- Computer, Computational, and Statistical Sciences Division, Los Alamos National Laboratory, Los Alamos, NM 875405, USA
| | - Mark A. Wilson
- Department of Biochemistry and Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
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2
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Grünberg S, Doyle LA, Wolf EJ, Dai N, Corrêa IR, Yigit E, Stoddard BL. The structural basis of mRNA recognition and binding by yeast pseudouridine synthase PUS1. PLoS One 2023; 18:e0291267. [PMID: 37939088 PMCID: PMC10631681 DOI: 10.1371/journal.pone.0291267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 08/25/2023] [Indexed: 11/10/2023] Open
Abstract
The chemical modification of RNA bases represents a ubiquitous activity that spans all domains of life. Pseudouridylation is the most common RNA modification and is observed within tRNA, rRNA, ncRNA and mRNAs. Pseudouridine synthase or 'PUS' enzymes include those that rely on guide RNA molecules and others that function as 'stand-alone' enzymes. Among the latter, several have been shown to modify mRNA transcripts. Although recent studies have defined the structural requirements for RNA to act as a PUS target, the mechanisms by which PUS1 recognizes these target sequences in mRNA are not well understood. Here we describe the crystal structure of yeast PUS1 bound to an RNA target that we identified as being a hot spot for PUS1-interaction within a model mRNA at 2.4 Å resolution. The enzyme recognizes and binds both strands in a helical RNA duplex, and thus guides the RNA containing the target uridine to the active site for subsequent modification of the transcript. The study also allows us to show the divergence of related PUS1 enzymes and their corresponding RNA target specificities, and to speculate on the basis by which PUS1 binds and modifies mRNA or tRNA substrates.
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Affiliation(s)
| | - Lindsey A. Doyle
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Eric J. Wolf
- New England Biolabs, Ipswich, Massachusetts, United States of America
| | - Nan Dai
- New England Biolabs, Ipswich, Massachusetts, United States of America
| | - Ivan R. Corrêa
- New England Biolabs, Ipswich, Massachusetts, United States of America
| | - Erbay Yigit
- New England Biolabs, Ipswich, Massachusetts, United States of America
| | - Barry L. Stoddard
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
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3
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Bernstein HJ, Andrews LC, Xerri M. An invertible seven-dimensional Dirichlet cell characterization of lattices. Acta Crystallogr A Found Adv 2023:S2053273323003121. [PMID: 37338213 DOI: 10.1107/s2053273323003121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2023] Open
Abstract
Characterization of crystallographic lattices is an important tool in structure solution, crystallographic database searches and clustering of diffraction images in serial crystallography. Characterization of lattices by Niggli-reduced cells (based on the three shortest non-coplanar lattice vectors) or by Delaunay-reduced cells (based on four non-coplanar vectors summing to zero and all meeting at obtuse or right angles) is commonly performed. The Niggli cell derives from Minkowski reduction. The Delaunay cell derives from Selling reduction. All are related to the Wigner-Seitz (or Dirichlet, or Voronoi) cell of the lattice, which consists of the points at least as close to a chosen lattice point as they are to any other lattice point. The three non-coplanar lattice vectors chosen are here called the Niggli-reduced cell edges. Starting from a Niggli-reduced cell, the Dirichlet cell is characterized by the planes determined by 13 lattice half-edges: the midpoints of the three Niggli cell edges, the six Niggli cell face-diagonals and the four body-diagonals, but seven of the lengths are sufficient: three edge lengths, the three shorter of each pair of face-diagonal lengths, and the shortest body-diagonal length. These seven are sufficient to recover the Niggli-reduced cell.
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Affiliation(s)
- Herbert J Bernstein
- Ronin Institute for Independent Scholarship, c/o NSLS-II, Brookhaven National Laboratory, Bldg 745, PO Box 5000, Upton, NY, USA
| | | | - Mario Xerri
- College of Engineering, Cornell University, Ithaca, NY, USA
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4
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Gillman C, Nicolas WJ, Martynowycz MW, Gonen T. Design and implementation of suspended drop crystallization. IUCrJ 2023; 10:S2052252523004141. [PMID: 37223996 DOI: 10.1107/s2052252523004141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 05/10/2023] [Indexed: 05/26/2023]
Abstract
In this work, a novel crystal growth method termed suspended drop crystallization has been developed. Unlike traditional methods, this technique involves mixing protein and precipitant directly on an electron microscopy grid without any additional support layers. The grid is then suspended within a crystallization chamber designed in-house, allowing for vapor diffusion to occur from both sides of the drop. A UV-transparent window above and below the grid enables the monitoring of crystal growth via light, UV or fluorescence microscopy. Once crystals have formed, the grid can be removed and utilized for X-ray crystallography or microcrystal electron diffraction (MicroED) directly without having to manipulate the crystals. To demonstrate the efficacy of this method, crystals of the enzyme proteinase K were grown and its structure was determined by MicroED following focused ion beam/scanning electron microscopy milling to render the sample thin enough for cryoEM. Suspended drop crystallization overcomes many of the challenges associated with sample preparation, providing an alternative workflow for crystals embedded in viscous media, sensitive to mechanical stress and/or subject to preferred orientation on electron microscopy grids.
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Affiliation(s)
- Cody Gillman
- Departments of Biological Chemistry and Physiology, University of California, Los Angeles, CA, USA
| | - William J Nicolas
- Departments of Biological Chemistry and Physiology, University of California, Los Angeles, CA, USA
| | - Michael W Martynowycz
- Departments of Biological Chemistry and Physiology, University of California, Los Angeles, CA, USA
| | - Tamir Gonen
- Departments of Biological Chemistry and Physiology, University of California, Los Angeles, CA, USA
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5
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Vallat B, Webb B, Fayazi M, Voinea S, Tangmunarunkit H, Ganesan SJ, Lawson CL, Westbrook JD, Kesselman C, Sali A, Berman HM. New system for archiving integrative structures. Acta Crystallogr D Struct Biol 2021; 77:1486-1496. [PMID: 34866606 PMCID: PMC8647179 DOI: 10.1107/s2059798321010871] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 10/19/2021] [Indexed: 11/30/2022] Open
Abstract
Structures of many complex biological assemblies are increasingly determined using integrative approaches, in which data from multiple experimental methods are combined. A standalone system, called PDB-Dev, has been developed for archiving integrative structures and making them publicly available. Here, the data standards and software tools that support PDB-Dev are described along with the new and updated components of the PDB-Dev data-collection, processing and archiving infrastructure. Following the FAIR (Findable, Accessible, Interoperable and Reusable) principles, PDB-Dev ensures that the results of integrative structure determinations are freely accessible to everyone.
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Affiliation(s)
- Brinda Vallat
- RCSB PDB, Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Benjamin Webb
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, and California Institute for Quantitative Biosciences, University of California at San Francisco, San Francisco, California, USA
| | - Maryam Fayazi
- RCSB PDB, Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Serban Voinea
- Information Sciences Institute, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
| | - Hongsuda Tangmunarunkit
- Information Sciences Institute, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
| | - Sai J. Ganesan
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, and California Institute for Quantitative Biosciences, University of California at San Francisco, San Francisco, California, USA
| | - Catherine L. Lawson
- RCSB PDB, Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - John D. Westbrook
- RCSB PDB, Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Carl Kesselman
- RCSB PDB, Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, and California Institute for Quantitative Biosciences, University of California at San Francisco, San Francisco, California, USA
| | - Helen M. Berman
- Department of Chemistry and Chemical Biology and Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
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6
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Kristensen LG, Holton JM, Rad B, Chen Y, Petzold CJ, Gupta S, Ralston CY. Hydroxyl radical mediated damage of proteins in low oxygen solution investigated using X-ray footprinting mass spectrometry. J Synchrotron Radiat 2021; 28:1333-1342. [PMID: 34475282 PMCID: PMC8415330 DOI: 10.1107/s1600577521004744] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 05/04/2021] [Indexed: 05/12/2023]
Abstract
In the method of X-ray footprinting mass spectrometry (XFMS), proteins at micromolar concentration in solution are irradiated with a broadband X-ray source, and the resulting hydroxyl radical modifications are characterized using liquid chromatography mass spectrometry to determine sites of solvent accessibility. These data are used to infer structural changes in proteins upon interaction with other proteins, folding, or ligand binding. XFMS is typically performed under aerobic conditions; dissolved molecular oxygen in solution is necessary in many, if not all, the hydroxyl radical modifications that are generally reported. In this study we investigated the result of X-ray induced modifications to three different proteins under aerobic versus low oxygen conditions, and correlated the extent of damage with dose calculations. We observed a concentration-dependent protecting effect at higher protein concentration for a given X-ray dose. For the typical doses used in XFMS experiments there was minimal X-ray induced aggregation and fragmentation, but for higher doses we observed formation of covalent higher molecular weight oligomers, as well as fragmentation, which was affected by the amount of dissolved oxygen in solution. The higher molecular weight products in the form of dimers, trimers, and tetramers were present in all sample preparations, and, upon X-ray irradiation, these oligomers became non-reducible as seen in SDS-PAGE. The results provide an important contribution to the large body of X-ray radiation damage literature in structural biology research, and will specifically help inform the future planning of XFMS, and well as X-ray crystallography and small-angle X-ray scattering experiments.
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Affiliation(s)
- Line G Kristensen
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - James M Holton
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Behzad Rad
- Molecular Foundry Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Yan Chen
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Christopher J Petzold
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Sayan Gupta
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Corie Y Ralston
- Molecular Foundry Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
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7
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Harris N, Benedict J, Dickie DA, Pagola S. Mechanochemical synthesis insights and solid-state characterization of quininium aspirinate, a glass-forming drug-drug salt. Acta Crystallogr C Struct Chem 2021; 77:566-576. [PMID: 34482301 PMCID: PMC8418670 DOI: 10.1107/s2053229621008275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 08/11/2021] [Indexed: 11/10/2022] Open
Abstract
Quinine (an antimalarial) and aspirin (a nonsteroidal anti-inflammatory drug) were combined into a new drug-drug salt, quininium aspirinate, C20H25N2O2+·C9H7O4-, by liquid-assisted grinding using stoichiometric amounts of the reactants in a 1:1 molar ratio, and water, EtOH, toluene, or heptane as additives. A tetrahydrofuran (THF) solution of the mechanochemical product prepared using EtOH as additive led to a single crystal of the same material obtained by mechanochemistry, which was used for crystal structure determination at 100 K. Powder X-ray diffraction ruled out crystallographic phase transitions in the 100-295 K interval. Neat mechanical treatment (in a mortar and pestle, or in a ball mill at 20 or 30 Hz milling frequencies) gave rise to an amorphous phase, as shown by powder X-ray diffraction; however, FT-IR spectroscopy unambiguously indicates that a mechanochemical reaction has occurred. Neat milling the reactants at 10 and 15 Hz led to incomplete reactions. Thermogravimetry and differential scanning calorimetry indicate that the amorphous and crystalline mechanochemical products form glasses/supercooled liquids before melting, and do not recrystallize upon cooling. However, the amorphous material obtained by neat grinding crystallizes upon storage into the salt reported. The mechanochemical synthesis, crystal structure analysis, Hirshfeld surfaces, powder X-ray diffraction, thermogravimetry, differential scanning calorimetry, FT-IR spectroscopy, and aqueous solubility of quininium aspirinate are herein reported.
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Affiliation(s)
- Nehemiah Harris
- Department of Chemistry and Biochemistry, Old Dominion University, 4402 Elkhorn Ave., Norfolk, VA 23529, USA
| | - Jubilee Benedict
- Department of Chemistry and Biochemistry, Old Dominion University, 4402 Elkhorn Ave., Norfolk, VA 23529, USA
| | - Diane A. Dickie
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
| | - Silvina Pagola
- Department of Chemistry and Biochemistry, Old Dominion University, 4402 Elkhorn Ave., Norfolk, VA 23529, USA
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8
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Olenginski GM, Piacentini J, Harris DR, Runko NA, Papoutsis BM, Alter JR, Hess KR, Brewer SH, Phillips-Piro CM. Structural and spectrophotometric investigation of two unnatural amino-acid altered chromophores in the superfolder green fluorescent protein. Acta Crystallogr D Struct Biol 2021; 77:1010-1018. [PMID: 34342274 PMCID: PMC8329867 DOI: 10.1107/s2059798321006525] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 06/21/2021] [Indexed: 11/10/2022] Open
Abstract
The spectrophotometric properties of the green fluorescent protein (GFP) result from the post-translationally cyclized chromophore composed of three amino acids including a tyrosine at the center of the β-barrel protein. Altering the amino acids in the chromophore or the nearby region has resulted in numerous GFP variants with differing photophysical properties. To further examine the effect of small atomic changes in the chromophore on the structure and photophysical properties of GFP, the hydroxyl group of the chromophore tyrosine was replaced with a nitro or a cyano group. The structures and spectrophotometric properties of these superfolder GFP (sfGFP) variants with the unnatural amino acids (UAAs) 4-nitro-L-phenylalanine or 4-cyano-L-phenylalanine were explored. Notably, the characteristic 487 nm absorbance band of wild-type (wt) sfGFP is absent in both unnatural amino-acid-containing protein constructs (Tyr66pNO2Phe-sfGFP and Tyr66pCNPhe-sfGFP). Consequently, neither Tyr66pNO2Phe-sfGFP nor Tyr66pCNPhe-sfGFP exhibited the characteristic emission of wt sfGFP centered at 511 nm when excited at 487 nm. Tyr66pNO2Phe-sfGFP appeared orange due to an absorbance band centered at 406 nm that was not present in wt sfGFP, while Tyr66pCNPhe-sfGFP appeared colorless with an absorbance band centered at 365 nm. Mass spectrometry and X-ray crystallography confirmed the presence of a fully formed chromophore and no significant structural changes in either of these UAA-containing protein constructs, signaling that the change in the observed photophysical properties of the proteins is the result of the presence of the UAA in the chromophore.
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Affiliation(s)
- Gregory M. Olenginski
- Department of Chemistry, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, USA
| | - Juliana Piacentini
- Department of Chemistry, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, USA
| | - Darcy R. Harris
- Department of Chemistry, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, USA
| | - Nicolette A. Runko
- Department of Chemistry, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, USA
| | - Brianna M. Papoutsis
- Department of Chemistry, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, USA
| | - Jordan R. Alter
- Department of Chemistry, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, USA
| | - Kenneth R. Hess
- Department of Chemistry, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, USA
| | - Scott H. Brewer
- Department of Chemistry, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, USA
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9
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Hatti KS, McCoy AJ, Read RJ. Likelihood-based estimation of substructure content from single-wavelength anomalous diffraction (SAD) intensity data. Acta Crystallogr D Struct Biol 2021; 77:880-893. [PMID: 34196615 PMCID: PMC8251343 DOI: 10.1107/s2059798321004538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 04/28/2021] [Indexed: 11/14/2022] Open
Abstract
SAD phasing can be challenging when the signal-to-noise ratio is low. In such cases, having an accurate estimate of the substructure content can determine whether or not the substructure of anomalous scatterer positions can successfully be determined. Here, a likelihood-based target function is proposed to accurately estimate the strength of the anomalous scattering contribution directly from the measured intensities, determining a complex correlation parameter relating the Bijvoet mates as a function of resolution. This gives a novel measure of the intrinsic anomalous signal. The SAD likelihood target function also accounts for correlated errors in the measurement of intensities from Bijvoet mates, which can arise from the effects of radiation damage. When the anomalous signal is assumed to come primarily from a substructure comprising one anomalous scatterer with a known value of f'' and when the protein composition of the crystal is estimated correctly, the refined complex correlation parameters can be interpreted in terms of the atomic content of the primary anomalous scatterer before the substructure is known. The maximum-likelihood estimation of substructure content was tested on a curated database of 357 SAD cases with useful anomalous signal. The prior estimates of substructure content are highly correlated to the content determined by phasing calculations, with a correlation coefficient (on a log-log basis) of 0.72.
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Affiliation(s)
- Kaushik S. Hatti
- Cambridge Institute for Medical Research, Department of Haematology, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, United Kingdom
| | - Airlie J. McCoy
- Cambridge Institute for Medical Research, Department of Haematology, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, United Kingdom
| | - Randy J. Read
- Cambridge Institute for Medical Research, Department of Haematology, University of Cambridge, The Keith Peters Building, Hills Road, Cambridge CB2 0XY, United Kingdom
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10
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Yang L, Lazo E, Byrnes J, Chodankar S, Antonelli S, Rakitin M. Tools for supporting solution scattering during the COVID-19 pandemic. J Synchrotron Radiat 2021; 28:1237-1244. [PMID: 34212889 PMCID: PMC8284406 DOI: 10.1107/s160057752100521x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 05/15/2021] [Indexed: 05/11/2023]
Abstract
During the COVID-19 pandemic, synchrotron beamlines were forced to limit user access. Performing routine measurements became a challenge. At the Life Science X-ray Scattering (LiX) beamline, new instrumentation and mail-in protocols have been developed to remove the access barrier to solution scattering measurements. Our efforts took advantage of existing instrumentation and coincided with the larger effort at NSLS-II to support remote measurements. Given the limited staff-user interaction for mail-in measurements, additional software tools have been developed to ensure data quality, to automate the adjustments in data processing, as users would otherwise rely on the experience of the beamline staff, and produce a summary of the initial assessments of the data. This report describes the details of these developments.
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Affiliation(s)
- Lin Yang
- Brookhaven National Laboratory, 745 Brookhaven Avenue, Upton, NY 11973, USA
| | - Edwin Lazo
- Brookhaven National Laboratory, 745 Brookhaven Avenue, Upton, NY 11973, USA
| | - James Byrnes
- Brookhaven National Laboratory, 745 Brookhaven Avenue, Upton, NY 11973, USA
| | - Shirish Chodankar
- Brookhaven National Laboratory, 745 Brookhaven Avenue, Upton, NY 11973, USA
| | - Stephen Antonelli
- Brookhaven National Laboratory, 745 Brookhaven Avenue, Upton, NY 11973, USA
| | - Maksim Rakitin
- Brookhaven National Laboratory, 745 Brookhaven Avenue, Upton, NY 11973, USA
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11
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Peck A, Yao Q, Brewster AS, Zwart PH, Heumann JM, Sauter NK, Jensen GJ. Challenges in solving structures from radiation-damaged tomograms of protein nanocrystals assessed by simulation. Acta Crystallogr D Struct Biol 2021; 77:572-586. [PMID: 33950014 PMCID: PMC8098477 DOI: 10.1107/s2059798321002369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Accepted: 03/02/2021] [Indexed: 11/11/2022] Open
Abstract
Structure-determination methods are needed to resolve the atomic details that underlie protein function. X-ray crystallography has provided most of our knowledge of protein structure, but is constrained by the need for large, well ordered crystals and the loss of phase information. The rapidly developing methods of serial femtosecond crystallography, micro-electron diffraction and single-particle reconstruction circumvent the first of these limitations by enabling data collection from nanocrystals or purified proteins. However, the first two methods also suffer from the phase problem, while many proteins fall below the molecular-weight threshold required for single-particle reconstruction. Cryo-electron tomography of protein nanocrystals has the potential to overcome these obstacles of mainstream structure-determination methods. Here, a data-processing scheme is presented that combines routines from X-ray crystallography and new algorithms that have been developed to solve structures from tomograms of nanocrystals. This pipeline handles image-processing challenges specific to tomographic sampling of periodic specimens and is validated using simulated crystals. The tolerance of this workflow to the effects of radiation damage is also assessed. The simulations indicate a trade-off between a wider tilt range to facilitate merging data from multiple tomograms and a smaller tilt increment to improve phase accuracy. Since phase errors, but not merging errors, can be overcome with additional data sets, these results recommend distributing the dose over a wide angular range rather than using a finer sampling interval to solve the protein structure.
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Affiliation(s)
- Ariana Peck
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Qing Yao
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Aaron S. Brewster
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Petrus H. Zwart
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Center for Advanced Mathematics in Energy Research Applications, Lawrence Berkeley National Laboratory, Berkeley CA 94720, USA
| | - John M. Heumann
- Department of Molecular, Cellular and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Nicholas K. Sauter
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Grant J. Jensen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
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12
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Abstract
Diffraction data acquired from cryocooled protein crystals often include diffraction from ice. Analysis of ice diffraction from crystals of three proteins shows that the ice formed within solvent cavities during rapid cooling is comprised of a stacking-disordered mixture of hexagonal and cubic planes, with the cubic plane fraction increasing with increasing cryoprotectant concentration and increasing cooling rate. Building on the work of Thorn and coworkers [Thorn et al. (2017), Acta Cryst. D73, 729-727], a revised metric is defined for detecting ice from deposited protein structure-factor data, and this metric is validated using full-frame diffraction data from the Integrated Resource for Reproducibility in Macromolecular Crystallography. Using this revised metric and improved algorithms, an analysis of structure-factor data from a random sample of 89 827 PDB entries collected at cryogenic temperatures indicates that roughly 16% show evidence of ice contamination, and that this fraction increases with increasing solvent content and maximum solvent-cavity size. By examining the ice diffraction-peak positions at which structure-factor perturbations are observed, it is found that roughly 25% of crystals exhibit ice with primarily hexagonal character, indicating that inadequate cooling rates and/or cryoprotectant concentrations were used, while the remaining 75% show ice with a stacking-disordered or cubic character.
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Affiliation(s)
- David W. Moreau
- Physics Department, Cornell University, Ithaca, NY 14853, USA
| | - Hakan Atakisi
- Physics Department, Cornell University, Ithaca, NY 14853, USA
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13
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Liebschner D, Afonine PV, Moriarty NW, Poon BK, Chen VB, Adams PD. CERES: a cryo-EM re-refinement system for continuous improvement of deposited models. Acta Crystallogr D Struct Biol 2021; 77:48-61. [PMID: 33404525 PMCID: PMC7787109 DOI: 10.1107/s2059798320015879] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 12/03/2020] [Indexed: 11/10/2022] Open
Abstract
The field of electron cryomicroscopy (cryo-EM) has advanced quickly in recent years as the result of numerous technological and methodological developments. This has led to an increase in the number of atomic structures determined using this method. Recently, several tools for the analysis of cryo-EM data and models have been developed within the Phenix software package, such as phenix.real_space_refine for the refinement of atomic models against real-space maps. Also, new validation metrics have been developed for low-resolution cryo-EM models. To understand the quality of deposited cryo-EM structures and how they might be improved, models deposited in the Protein Data Bank that have map resolutions of better than 5 Å were automatically re-refined using current versions of Phenix tools. The results are available on a publicly accessible web page (https://cci.lbl.gov/ceres). The implementation of a Cryo-EM Re-refinement System (CERES) for the improvement of models deposited in the wwPDB, and the results of the re-refinements, are described. Based on these results, contents are proposed for a `cryo-EM Table 1', which summarizes experimental details and validation metrics in a similar way to `Table 1' in crystallography. The consistent use of robust metrics for the evaluation of cryo-EM models and data should accompany every structure deposition and be reported in scientific publications.
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Affiliation(s)
- Dorothee Liebschner
- Molecular Biosciences and Integrated Bioimaging, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Pavel V. Afonine
- Molecular Biosciences and Integrated Bioimaging, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Nigel W. Moriarty
- Molecular Biosciences and Integrated Bioimaging, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Billy K. Poon
- Molecular Biosciences and Integrated Bioimaging, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Vincent B. Chen
- Department of Biochemistry, Duke University, Durham, NC 27710, USA
| | - Paul D. Adams
- Molecular Biosciences and Integrated Bioimaging, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
- Department of Bioengineering, University of California Berkeley, Berkeley, CA 94720, USA
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14
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McLoughlin F, Marshall RS, Ding X, Chatt EC, Kirkpatrick LD, Augustine RC, Li F, Otegui MS, Vierstra RD. Autophagy Plays Prominent Roles in Amino Acid, Nucleotide, and Carbohydrate Metabolism during Fixed-Carbon Starvation in Maize. Plant Cell 2020; 32:2699-2724. [PMID: 32616663 PMCID: PMC7474275 DOI: 10.1105/tpc.20.00226] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 06/04/2020] [Accepted: 06/27/2020] [Indexed: 05/31/2023]
Abstract
Autophagic recycling of proteins, lipids, nucleic acids, carbohydrates, and organelles is essential for cellular homeostasis and optimal health, especially under nutrient-limiting conditions. To better understand how this turnover affects plant growth, development, and survival upon nutrient stress, we applied an integrated multiomics approach to study maize (Zea mays) autophagy mutants subjected to fixed-carbon starvation induced by darkness. Broad metabolic alterations were evident in leaves missing the core autophagy component ATG12 under normal growth conditions (e.g., lipids and secondary metabolism), while changes in amino acid-, carbohydrate-, and nucleotide-related metabolites selectively emerged during fixed-carbon starvation. Through combined proteomic and transcriptomic analyses, we identified numerous autophagy-responsive proteins, which revealed processes underpinning the various metabolic changes seen during carbon stress as well as potential autophagic cargo. Strikingly, a strong upregulation of various catabolic processes was observed in the absence of autophagy, including increases in simple carbohydrate levels with a commensurate drop in starch levels, elevated free amino acid levels with a corresponding reduction in intact protein levels, and a strong increase in the abundance of several nitrogen-rich nucleotide catabolites. Altogether, this analysis showed that fixed-carbon starvation in the absence of autophagy adjusts the choice of respiratory substrates, promotes the transition of peroxisomes to glyoxysomes, and enhances the retention of assimilated nitrogen.
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Affiliation(s)
- Fionn McLoughlin
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130
| | - Richard S Marshall
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130
| | - Xinxin Ding
- Department of Botany, University of Wisconsin, Madison, Wisconsin 53706
- Center for Quantitative Cell Imaging, University of Wisconsin, Madison, Wisconsin 53706
| | - Elizabeth C Chatt
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130
| | - Liam D Kirkpatrick
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130
| | - Robert C Augustine
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130
| | - Faqiang Li
- Department of Genetics, University of Wisconsin, Madison, Wisconsin 53706
| | - Marisa S Otegui
- Department of Botany, University of Wisconsin, Madison, Wisconsin 53706
- Center for Quantitative Cell Imaging, University of Wisconsin, Madison, Wisconsin 53706
| | - Richard D Vierstra
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130
- Department of Genetics, University of Wisconsin, Madison, Wisconsin 53706
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15
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Zeytuni N, Dickey SW, Hu J, Chou HT, Worrall LJ, Alexander JAN, Carlson ML, Nosella M, Duong F, Yu Z, Otto M, Strynadka NCJ. Structural insight into the Staphylococcus aureus ATP-driven exporter of virulent peptide toxins. Sci Adv 2020; 6:eabb8219. [PMID: 32998902 PMCID: PMC7527219 DOI: 10.1126/sciadv.abb8219] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 08/14/2020] [Indexed: 06/06/2023]
Abstract
Staphylococcus aureus is a major human pathogen that has acquired alarming broad-spectrum antibiotic resistance. One group of secreted toxins with key roles during infection is the phenol-soluble modulins (PSMs). PSMs are amphipathic, membrane-destructive cytolytic peptides that are exported to the host-cell environment by a designated adenosine 5'-triphosphate (ATP)-binding cassette (ABC) transporter, the PSM transporter (PmtABCD). Here, we demonstrate that the minimal Pmt unit necessary for PSM export is PmtCD and provide its first atomic characterization by single-particle cryo-EM and x-ray crystallography. We have captured the transporter in the ATP-bound state at near atomic resolution, revealing a type II ABC exporter fold, with an additional cytosolic domain. Comparison to a lower-resolution nucleotide-free map displaying an "open" conformation and putative hydrophobic inner chamber of a size able to accommodate the binding of two PSM peptides provides mechanistic insight and sets the foundation for therapeutic design.
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Affiliation(s)
- N. Zeytuni
- Department of Biochemistry and Molecular Biology and the Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - S. W. Dickey
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - J. Hu
- Department of Biochemistry and Molecular Biology and the Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - H. T. Chou
- CryoEM Shared Resources, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - L. J. Worrall
- Department of Biochemistry and Molecular Biology and the Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
- High Resolution Macromolecular Cryo-Electron Microscopy facility, University of British Columbia, Vancouver, V6T 1Z3, BC, Canada
| | - J. A. N. Alexander
- Department of Biochemistry and Molecular Biology and the Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - M. L. Carlson
- Department of Biochemistry and Molecular Biology and the Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - M. Nosella
- Department of Biochemistry and Molecular Biology and the Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - F. Duong
- Department of Biochemistry and Molecular Biology and the Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
| | - Z. Yu
- CryoEM Shared Resources, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - M. Otto
- CryoEM Shared Resources, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - N. C. J. Strynadka
- Department of Biochemistry and Molecular Biology and the Centre for Blood Research, University of British Columbia, Vancouver, BC, Canada
- High Resolution Macromolecular Cryo-Electron Microscopy facility, University of British Columbia, Vancouver, V6T 1Z3, BC, Canada
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16
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Bonn-Breach R, Gu Y, Jenkins J, Fasan R, Wedekind J. Structure of Sonic Hedgehog protein in complex with zinc(II) and magnesium(II) reveals ion-coordination plasticity relevant to peptide drug design. Acta Crystallogr D Struct Biol 2019; 75:969-979. [PMID: 31692471 PMCID: PMC6834079 DOI: 10.1107/s2059798319012890] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 09/17/2019] [Indexed: 12/21/2022] Open
Abstract
The Hedgehog pathway is an essential cell-signaling paradigm implicated in cancer tumorigenesis and the developmental disorder holoprosencephaly, making it an attractive target for therapeutic design. The N-terminal domain of the Sonic Hedgehog protein (Shh-N) is the essential signaling molecule in the Hedgehog pathway. In this role Shh-N interacts with its cognate membrane receptor Patched, as well as the regulatory proteins HHIP and CDO, by utilizing interfaces harboring one or more divalent ions. Here, the crystal structure of human Shh-N is presented at 1.43 Å resolution, representing a landmark in the characterization of this protein. The structure reveals that the conserved Zn2+-binding site adopts an atypical octahedral coordination geometry, whereas an adjacent binding site, normally occupied by binuclear Ca2+, has been supplanted by a single octahedrally bound Mg2+. Both divalent sites are compared with those in previous Shh-N structures, which demonstrates a significant degree of plasticity of the Shh-N protein in terms of divalent ion binding. The presence of a high Mg2+ concentration in the crystallization medium appears to have influenced metal loading at both metal ion-binding sites. These observations have technical and design implications for efforts focused on the development of inhibitors that target Shh-N-mediated protein-protein interactions.
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Affiliation(s)
- Rachel Bonn-Breach
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Yu Gu
- Department of Chemistry, University of Rochester, 120 Trustee Road, Rochester, NY 14627, USA
| | - Jermaine Jenkins
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Rudi Fasan
- Department of Chemistry, University of Rochester, 120 Trustee Road, Rochester, NY 14627, USA
| | - Joseph Wedekind
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
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17
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Taberman H, Bury CS, van der Woerd MJ, Snell EH, Garman EF. Structural knowledge or X-ray damage? A case study on xylose isomerase illustrating both. J Synchrotron Radiat 2019; 26:931-944. [PMID: 31274415 PMCID: PMC6613113 DOI: 10.1107/s1600577519005599] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Accepted: 04/23/2019] [Indexed: 05/29/2023]
Abstract
Xylose isomerase (XI) is an industrially important metalloprotein studied for decades. Its reaction mechanism has been postulated to involve movement of the catalytic metal cofactor to several different conformations. Here, a dose-dependent approach was used to investigate the radiation damage effects on XI and their potential influence on the reaction mechanism interpreted from the X-ray derived structures. Radiation damage is still one of the major challenges for X-ray diffraction experiments and causes both global and site-specific damage. In this study, consecutive high-resolution data sets from a single XI crystal from the same wedge were collected at 100 K and the progression of radiation damage was tracked over increasing dose (0.13-3.88 MGy). The catalytic metal and its surrounding amino acid environment experience a build-up of free radicals, and the results show radiation-damage-induced structural perturbations ranging from an absolute metal positional shift to specific residue motions in the active site. The apparent metal movement is an artefact of global damage and the resulting unit-cell expansion, but residue motion appears to be driven by the dose. Understanding and identifying radiation-induced damage is an important factor in accurately interpreting the biological conclusions being drawn.
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Affiliation(s)
- Helena Taberman
- Macromolecular Crystallography (HZB-MX), Helmholtz-Zentrum Berlin, Albert-Einstein Straße 15, 12489 Berlin, Germany
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Charles S. Bury
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Mark J. van der Woerd
- Department of Enterprise Technology Services, 2001 Capitol Avenue, Cheyenne, WY 82001, USA
| | - Edward H. Snell
- Hauptman-Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY 14203, USA
- Materials Design and Innovation, State University of New York at Buffalo, 700 Ellicott Street, Buffalo, NY 14203, USA
| | - Elspeth F. Garman
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
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18
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Choudury SG, Shahid S, Cuerda-Gil D, Panda K, Cullen A, Ashraf Q, Sigman MJ, McCue AD, Slotkin RK. The RNA Export Factor ALY1 Enables Genome-Wide RNA-Directed DNA Methylation. Plant Cell 2019; 31:759-774. [PMID: 30814259 PMCID: PMC6501602 DOI: 10.1105/tpc.18.00624] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 01/23/2019] [Accepted: 02/22/2019] [Indexed: 05/07/2023]
Abstract
RNA-directed DNA methylation (RdDM) is a set of mechanisms by which transcriptionally repressive DNA and histone methylation are targeted to viruses, transposable elements, and some transgenes. We identified an Arabidopsis (Arabidopsis thaliana) mutant in which all forms of RdDM are deficient, leading to transcriptional activation of some transposable elements and the inability to initiate transgene silencing. The corresponding gene, ALY1, encodes an RNA binding nuclear export protein. Arabidopsis ALY proteins function together to export many messenger RNAs (mRNAs), but we found that ALY1 is unique among this family for its ability to enable RdDM. Through the identification of ALY1 direct targets via RNA immunoprecipitation sequencing, coupled with mRNA sequencing of nuclear and cytoplasmic fractions, we identified mRNAs of known RdDM factors that fail to efficiently export from the nucleus in aly1 mutants. We found that loss of RdDM in aly1 is a result of deficient nuclear export of the ARGONAUTE6 mRNA and subsequent decreases in ARGONAUTE6 protein, a key effector of RdDM. One aly1 allele was more severe due to an additional loss of RNA Polymerase V function, which is also necessary for RdDM. Together, our data reconcile the broad role of ALY1 in mRNA export with the specific loss of RdDM through the activities of ARGONAUTE6 and RNA Polymerase V.
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Affiliation(s)
- Sarah G Choudury
- Molecular, Cellular and Developmental Biology Graduate Program, The Ohio State University, Columbus, Ohio 43210
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210
| | - Saima Shahid
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132
| | - Diego Cuerda-Gil
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210
| | - Kaushik Panda
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132
| | - Alissa Cullen
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210
| | - Quratulayn Ashraf
- Molecular, Cellular and Developmental Biology Graduate Program, The Ohio State University, Columbus, Ohio 43210
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210
| | - Meredith J Sigman
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210
| | - Andrea D McCue
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210
| | - R Keith Slotkin
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211
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19
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Wetherill MS, Davis GC, Kezbers K, Carter V, Wells E, Williams MB, Ijams SD, Monlezun D, Harlan T, Whelan LJ. Development and Evaluation of a Nutrition-Centered Lifestyle Medicine Curriculum for Physician Assistant Students. Med Sci Educ 2019; 29:163-172. [PMID: 34457464 PMCID: PMC8368925 DOI: 10.1007/s40670-018-00655-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
BACKGROUND US medical schools are increasingly integrating lifestyle medicine competencies into their academic programs. Yet, physician assistant (PA) academic programs have been slower to respond. METHODS We developed, implemented, and evaluated a nutrition-centered lifestyle medicine curriculum for 2nd-year PA students (n = 24). The 4-week hybrid, 2-credit hour course activities aligned with the American College of Lifestyle Medicine competencies for primary care providers and reinforced four of the Accreditation Standards for PA Education. We combined didactic lectures with weekly hands-on cooking modules from the "Health meets Food" courseware for medical students. We employed a pre-post evaluation design including a comparison group of 2nd-year PA students in a separate program. We assessed changes in personal nutrition behaviors and knowledge and confidence for counseling in nutrition, exercise/physical activity, weight, smoking, and alcohol, using the modified 5A's framework (assess, advise, agree, assist, and arrange) for lifestyle counseling. RESULTS Students receiving the intervention demonstrated significantly higher gains in both knowledge and confidence for the 5A's of nutrition counseling compared to the control group. Self-reported knowledge and confidence for the 5A's of counseling for the other lifestyle behaviors similarly improved among the intervention group compared to the control group, but to a lesser extent. CONCLUSION A nutrition-centered lifestyle medicine course can demonstrate PA academic program adherence to accreditation standards, while also introducing students to nutrition and lifestyle medicine competencies. Hands-on experiences that reinforce didactic instruction may maximize student knowledge and self-efficacy for implementing lifestyle medicine into their practice.
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Affiliation(s)
- Marianna S. Wetherill
- Hudson College of Public Health, University of Oklahoma - Tulsa Schusterman Center, 4502 E. 41st Street, Tulsa, OK 74135 USA
- University of Oklahoma School of Community Medicine, Tulsa, OK 74135 USA
| | - Gracen C. Davis
- University of Oklahoma School of Community Medicine, Tulsa, OK 74135 USA
| | - Krista Kezbers
- University of Oklahoma School of Community Medicine, Tulsa, OK 74135 USA
| | - Valarie Carter
- Hudson College of Public Health, University of Oklahoma - Tulsa Schusterman Center, 4502 E. 41st Street, Tulsa, OK 74135 USA
| | - Elizabeth Wells
- University of Oklahoma School of Community Medicine, Tulsa, OK 74135 USA
| | - Mary B. Williams
- Hudson College of Public Health, University of Oklahoma - Tulsa Schusterman Center, 4502 E. 41st Street, Tulsa, OK 74135 USA
- University of Oklahoma School of Community Medicine, Tulsa, OK 74135 USA
| | - Shannon D. Ijams
- University of Oklahoma School of Community Medicine, Tulsa, OK 74135 USA
| | | | - Timothy Harlan
- Tulane University School of Medicine, New Orleans, LA 70112 USA
| | - Lori J. Whelan
- University of Oklahoma School of Community Medicine, Tulsa, OK 74135 USA
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20
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Roth MS, Gallaher SD, Westcott DJ, Iwai M, Louie KB, Mueller M, Walter A, Foflonker F, Bowen BP, Ataii NN, Song J, Chen JH, Blaby-Haas CE, Larabell C, Auer M, Northen TR, Merchant SS, Niyogi KK. Regulation of Oxygenic Photosynthesis during Trophic Transitions in the Green Alga Chromochloris zofingiensis. Plant Cell 2019; 31:579-601. [PMID: 30787178 PMCID: PMC6482638 DOI: 10.1105/tpc.18.00742] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 12/18/2018] [Accepted: 02/15/2019] [Indexed: 05/04/2023]
Abstract
Light and nutrients are critical regulators of photosynthesis and metabolism in plants and algae. Many algae have the metabolic flexibility to grow photoautotrophically, heterotrophically, or mixotrophically. Here, we describe reversible Glc-dependent repression/activation of oxygenic photosynthesis in the unicellular green alga Chromochloris zofingiensis. We observed rapid and reversible changes in photosynthesis, in the photosynthetic apparatus, in thylakoid ultrastructure, and in energy stores including lipids and starch. Following Glc addition in the light, C. zofingiensis shuts off photosynthesis within days and accumulates large amounts of commercially relevant bioproducts, including triacylglycerols and the high-value nutraceutical ketocarotenoid astaxanthin, while increasing culture biomass. RNA sequencing reveals reversible changes in the transcriptome that form the basis of this metabolic regulation. Functional enrichment analyses show that Glc represses photosynthetic pathways while ketocarotenoid biosynthesis and heterotrophic carbon metabolism are upregulated. Because sugars play fundamental regulatory roles in gene expression, physiology, metabolism, and growth in both plants and animals, we have developed a simple algal model system to investigate conserved eukaryotic sugar responses as well as mechanisms of thylakoid breakdown and biogenesis in chloroplasts. Understanding regulation of photosynthesis and metabolism in algae could enable bioengineering to reroute metabolism toward beneficial bioproducts for energy, food, pharmaceuticals, and human health.
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Affiliation(s)
- Melissa S Roth
- Howard Hughes Medical Institute, Department of Plant and Microbial Biology, University of California, Berkeley, California 94720-3102
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Sean D Gallaher
- Department of Chemistry and Biochemistry and Institute for Genomics and Proteomics, University of California, Los Angeles, California 90095-1569
| | - Daniel J Westcott
- Howard Hughes Medical Institute, Department of Plant and Microbial Biology, University of California, Berkeley, California 94720-3102
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Masakazu Iwai
- Howard Hughes Medical Institute, Department of Plant and Microbial Biology, University of California, Berkeley, California 94720-3102
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Katherine B Louie
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, California 94598
| | - Maria Mueller
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Andreas Walter
- Department of Anatomy, University of California, San Francisco, California 94143
- National Center for X-ray Tomography, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Fatima Foflonker
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973
| | - Benjamin P Bowen
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, California 94598
| | - Nassim N Ataii
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Junha Song
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Jian-Hua Chen
- Department of Anatomy, University of California, San Francisco, California 94143
- National Center for X-ray Tomography, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | | | - Carolyn Larabell
- Department of Anatomy, University of California, San Francisco, California 94143
- National Center for X-ray Tomography, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Manfred Auer
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Trent R Northen
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, California 94598
| | - Sabeeha S Merchant
- Department of Chemistry and Biochemistry and Institute for Genomics and Proteomics, University of California, Los Angeles, California 90095-1569
| | - Krishna K Niyogi
- Howard Hughes Medical Institute, Department of Plant and Microbial Biology, University of California, Berkeley, California 94720-3102
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
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21
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Abstract
A synthetic data set demonstrating a particularly challenging case of indexing ambiguity in the context of radiation damage was generated. This set shall serve as a standard benchmark and reference point for the ongoing development of new methods and new approaches to robust structure solution when single-crystal methods are insufficient. Of the 100 short wedges of data, only the first 36 are currently necessary to solve the structure by `cheating', or using the correct reference structure as a guide. The total wall-clock time and number of crystals required to solve the structure without cheating is proposed as a metric for the efficacy and efficiency of a given multi-crystal automation pipeline.
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Affiliation(s)
- James M. Holton
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158-2330, USA
- Divison of Molecular Biophysics and Bioengineering, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
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22
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Harp JM, Coates L, Sullivan B, Egli M. Cryo-neutron crystallographic data collection and preliminary refinement of left-handed Z-DNA d(CGCGCG). Acta Crystallogr F Struct Biol Commun 2018; 74:603-609. [PMID: 30279310 PMCID: PMC6168769 DOI: 10.1107/s2053230x1801066x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 07/24/2018] [Indexed: 11/10/2022] Open
Abstract
Crystals of left-handed Z-DNA [d(CGCGCG)]2 diffract X-rays to beyond 1 Å resolution, feature a small unit cell (∼18 × 31 × 44 Å) and are well hydrated, with around 90 water molecules surrounding the duplex in the asymmetric unit. The duplex shows regular hydration patterns in the narrow minor groove, on the convex surface and around sugar-phosphate backbones. Therefore, Z-DNA offers an ideal case to test the benefits of low-temperature neutron diffraction data collection to potentially determine the donor-acceptor patterns of first- and second-shell water molecules. Nucleic acid fragments pose challenges for neutron crystallography because water molecules are located on the surface rather than inside sequestered spaces such as protein active sites or channels. Water molecules can be expected to display dynamic behavior, particularly in cases where water is not part of an inner shell and directly coordinated to DNA atoms. Thus, nuclear density maps based on room-temperature diffraction data with a resolution of 1.6 Å did not allow an unequivocal determination of the orientations of water molecules. Here, cryo-neutron diffraction data collection for a Z-DNA crystal on the Macromolecular Neutron Diffractometer at the Spallation Neutron Source at Oak Ridge National Laboratory and the outcome of an initial refinement of the structure are reported. A total of 12 diffraction images were recorded with an exposure time of 3.5 h per image, whereby the crystal was static for each diffraction image with a 10° ϕ rotation between images. Initial refinements using these neutron data indicated the positions and orientations of 30 water molecules within the first hydration shell of the DNA molecule. This experiment constitutes a state-of-the-art approach and is the first attempt to our knowledge to determine the low-temperature neutron structure of a DNA crystal.
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Affiliation(s)
- Joel M. Harp
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Leighton Coates
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Brendan Sullivan
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Martin Egli
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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23
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Terwilliger TC, Sobolev OV, Afonine PV, Adams PD. Automated map sharpening by maximization of detail and connectivity. Acta Crystallogr D Struct Biol 2018; 74:545-559. [PMID: 29872005 PMCID: PMC6096490 DOI: 10.1107/s2059798318004655] [Citation(s) in RCA: 156] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 03/21/2018] [Indexed: 01/18/2023] Open
Abstract
An algorithm for automatic map sharpening is presented that is based on optimization of the detail and connectivity of the sharpened map. The detail in the map is reflected in the surface area of an iso-contour surface that contains a fixed fraction of the volume of the map, where a map with high level of detail has a high surface area. The connectivity of the sharpened map is reflected in the number of connected regions defined by the same iso-contour surfaces, where a map with high connectivity has a small number of connected regions. By combining these two measures in a metric termed the `adjusted surface area', map quality can be evaluated in an automated fashion. This metric was used to choose optimal map-sharpening parameters without reference to a model or other interpretations of the map. Map sharpening by optimization of the adjusted surface area can be carried out for a map as a whole or it can be carried out locally, yielding a locally sharpened map. To evaluate the performance of various approaches, a simple metric based on map-model correlation that can reproduce visual choices of optimally sharpened maps was used. The map-model correlation is calculated using a model with B factors (atomic displacement factors; ADPs) set to zero. This model-based metric was used to evaluate map sharpening and to evaluate map-sharpening approaches, and it was found that optimization of the adjusted surface area can be an effective tool for map sharpening.
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Affiliation(s)
- Thomas C. Terwilliger
- Bioscience Division, Los Alamos National Laboratory, Mail Stop M888, Los Alamos, NM 87545, USA
- New Mexico Consortium, Los Alamos, NM 87544, USA
| | - Oleg V. Sobolev
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Pavel V. Afonine
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Bioengineering, University of California Berkeley, Berkeley, California, USA
| | - Paul D. Adams
- Department of Bioengineering, University of California Berkeley, Berkeley, California, USA
- Department of Physics and International Centre for Quantum and Molecular Structures, Shanghai University, Shanghai, 200444, People’s Republic of China
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24
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Atakisi H, Moreau DW, Thorne RE. Effects of protein-crystal hydration and temperature on side-chain conformational heterogeneity in monoclinic lysozyme crystals. Acta Crystallogr D Struct Biol 2018; 74:264-278. [PMID: 29652254 PMCID: PMC5892876 DOI: 10.1107/s2059798318000207] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 01/03/2018] [Indexed: 01/12/2023] Open
Abstract
The modulation of main-chain and side-chain conformational heterogeneity and solvent structure in monoclinic lysozyme crystals by dehydration (related to water activity) and temperature is examined. Decreasing the relative humidity (from 99 to 11%) and decreasing the temperature both lead to contraction of the unit cell, to an increased area of crystal contacts and to remodeling of primarily contact and solvent-exposed residues. Both lead to the depopulation of some minor side-chain conformers and to the generation of new conformations. Side-chain modifications and main-chain r.m.s.d.s associated with cooling from 298 to 100 K depend on relative humidity and are minimized at 85% relative humidity (r.h.). Dehydration from 99 to 93% r.h. and cooling from 298 to 100 K result in a comparable number of remodeled residues, with dehydration-induced remodeling somewhat more likely to arise from contact interactions. When scaled to equivalent temperatures based on unit-cell contraction, the evolution of side-chain order parameters with dehydration shows generally similar features to those observed on cooling to T = 100 K. These results illuminate the qualitative and quantitative similarities between structural perturbations induced by modest dehydration, which routinely occurs in samples prepared for 298 and 100 K data collection, and cryocooling. Differences between these perturbations in terms of energy landscapes and occupancies, and implications for variable-temperature crystallography between 180 and 298 K, are discussed. It is also noted that remodeling of a key lysozyme active-site residue by dehydration, which is associated with a radical decrease in the enzymatic activity of lysozyme powder, arises due to a steric clash with the residue of a symmetry mate.
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Affiliation(s)
- Hakan Atakisi
- Physics Department, Cornell University, Ithaca, NY 14853, USA
| | - David W. Moreau
- Physics Department, Cornell University, Ithaca, NY 14853, USA
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25
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Richardson JS, Williams CJ, Hintze BJ, Chen VB, Prisant MG, Videau LL, Richardson DC. Model validation: local diagnosis, correction and when to quit. Acta Crystallogr D Struct Biol 2018; 74:132-142. [PMID: 29533239 PMCID: PMC5947777 DOI: 10.1107/s2059798317009834] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 07/03/2017] [Indexed: 02/07/2023] Open
Abstract
Traditionally, validation was considered to be a final gatekeeping function, but refinement is smoother and results are better if model validation actively guides corrections throughout structure solution. This shifts emphasis from global to local measures: primarily geometry, conformations and sterics. A fit into the wrong local minimum conformation usually produces outliers in multiple measures. Moving to the right local minimum should be prioritized, rather than small shifts across arbitrary borderlines. Steric criteria work best with all explicit H atoms. `Backrub' motions should be used for side chains and `P-perp' diagnostics to correct ribose puckers. A `water' may actually be an ion, a relic of misfitting or an unmodeled alternate. Beware of wishful thinking in modeling ligands. At high resolution, internally consistent alternate conformations should be modeled and geometry in poor density should not be downweighted. At low resolution, CaBLAM should be used to diagnose protein secondary structure and ERRASER to correct RNA backbone. All atoms should not be forced inside density, beware of sequence misalignment, and very rare conformations such as cis-non-Pro peptides should be avoided. Automation continues to improve, but the crystallographer still must look at each outlier, in the context of density, and correct most of them. For the valid few with unambiguous density and something that is holding them in place, a functional reason should be sought. The expectation is a few outliers, not zero.
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Affiliation(s)
| | | | | | - Vincent B. Chen
- Department of Biochemistry, Duke University, Durham, NC 27710, USA
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26
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Winter G, Waterman DG, Parkhurst JM, Brewster AS, Gildea RJ, Gerstel M, Fuentes-Montero L, Vollmar M, Michels-Clark T, Young ID, Sauter NK, Evans G. DIALS: implementation and evaluation of a new integration package. Acta Crystallogr D Struct Biol 2018; 74:85-97. [PMID: 29533234 PMCID: PMC5947772 DOI: 10.1107/s2059798317017235] [Citation(s) in RCA: 642] [Impact Index Per Article: 107.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 11/30/2017] [Indexed: 01/07/2023] Open
Abstract
The DIALS project is a collaboration between Diamond Light Source, Lawrence Berkeley National Laboratory and CCP4 to develop a new software suite for the analysis of crystallographic X-ray diffraction data, initially encompassing spot finding, indexing, refinement and integration. The design, core algorithms and structure of the software are introduced, alongside results from the analysis of data from biological and chemical crystallography experiments.
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Affiliation(s)
- Graeme Winter
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - David G. Waterman
- STFC Rutherford Appleton Laboratory, Didcot OX11 0FA, England
- CCP4, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot OX11 0FA, England
| | - James M. Parkhurst
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
- Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, England
| | - Aaron S. Brewster
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Richard J. Gildea
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - Markus Gerstel
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - Luis Fuentes-Montero
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - Melanie Vollmar
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - Tara Michels-Clark
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Iris D. Young
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Nicholas K. Sauter
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Gwyndaf Evans
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
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27
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Abstract
A wide variety of crystallization solutions are screened to establish conditions that promote the growth of a diffraction-quality crystal. Screening these conditions requires the assessment of many crystallization plates for the presence of crystals. Automated systems for screening and imaging are very expensive. A simple approach to imaging trace fluorescently labeled protein crystals in crystallization plates has been devised, and can be implemented at a cost as low as $50. The proteins β-lactoglobulin B, trypsin and purified concanavalin A (ConA) were trace fluorescently labeled using three different fluorescent probes: Cascade Yellow (CY), Carboxyrhodamine 6G (CR) and Pacific Blue (PB). A crystallization screening plate was set up using β-lactoglobulin B labeled with CR, trypsin labeled with CY, ConA labeled with each probe, and a mixture consisting of 50% PB-labeled ConA and 50% CR-labeled ConA. The wells of these plates were imaged using a commercially available macro-imaging lens attachment for smart devices that have a camera. Several types of macro lens attachments were tested with smartphones and tablets. Images with the highest quality were obtained with an iPhone 6S and an AUKEY Ora 10× macro lens. Depending upon the fluorescent probe employed and its Stokes shift, a light-emitting diode or a laser diode was used for excitation. An emission filter was used for the imaging of protein crystals labeled with CR and crystals with two-color fluorescence. This approach can also be used with microscopy systems commonly used to observe crystallization plates.
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Affiliation(s)
- Crissy L. Tarver
- Department of Biological Science, University of Alabama in Huntsville, Huntsville, AL 35899, USA
| | - Marc Pusey
- Department of Biological Science, University of Alabama in Huntsville, Huntsville, AL 35899, USA
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28
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Hintze BJ, Richardson JS, Richardson DC. Mismodeled purines: implicit alternates and hidden Hoogsteens. Acta Crystallogr D Struct Biol 2017; 73:852-859. [PMID: 28994414 PMCID: PMC5633910 DOI: 10.1107/s2059798317013729] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 09/25/2017] [Indexed: 12/14/2022] Open
Abstract
Hoogsteen base pairs are seen in DNA crystal structures, but only rarely. This study tests whether Hoogsteens or other syn purines are either under-modeled or over-modeled, which are known problems for rare conformations. Candidate purines needing a syn/anti 180° flip were identified by diagnostic patterns of difference electron-density peaks. Manual inspection narrowed 105 flip candidates to 20 convincing cases, all at ≤2.7 Å resolution. Rebuilding and refinement confirmed that 14 of these were authentic purine flips. Seven examples are modeled as Watson-Crick base pairs but should be Hoogsteens (commonest at duplex termini), and three had the opposite issue. Syn/anti flips were also needed for some single-stranded purines. Five of the 20 convincing cases arose from an unmodeled alternate duplex running in the opposite direction. These are in semi-palindromic DNA sequences bound by a homodimeric protein and show flipped-purine-like difference peaks at residues where the palindrome is imperfect. This study documents types of incorrect modeling which are worth avoiding. However, the primary conclusions are that such mistakes are infrequent, the bias towards fitting anti purines is very slight, and the occurrence rate of Hoogsteen base pairs in DNA crystal structures remains unchanged from earlier estimates at ∼0.3%.
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29
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Kwaa AK, Goldsborough K, Walker-Sperling VE, Pianowski LF, Gama L, Blankson JN. The effect of Ingenol-B on the suppressive capacity of elite suppressor HIV-specific CD8+ T cells. PLoS One 2017; 12:e0174516. [PMID: 28467486 PMCID: PMC5414940 DOI: 10.1371/journal.pone.0174516] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 03/10/2017] [Indexed: 11/25/2022] Open
Abstract
Background Some latency-reversing agents (LRAs) inhibit HIV-specific CD8+ T cell responses. In a prior study of protein kinase C (PKC) agonists, we found that bryostatin-1 inhibited elite controller/suppressor (ES) CD8+ T cell suppressive activity whereas prostratin had no effect. Ingenol-B is another PKC agonist with potent LRA activity both by itself and in combination with the bromodomain inhibitor JQ1; however its effect on CD8+ T cell mediated control of HIV-1 replication is unknown. Methods CD8+ T cells were isolated from ES and treated with bryostatin-1, prostratin, ingenol-B, and JQ1 as well as a combination of each PKC-agonist with JQ1. The cells were then tested in the viral suppression assay. To assess possible mechanisms of inhibition, CD8+ T cells were treated with the LRAs and analyzed for the expression of various immune cell markers. Results Ingenol-B had no effect on the ability of ES CD8+ T cells to suppress viral replication, however, the combination of ingenol-B and JQ1 caused a modest, but significant decrease in this suppressive capacity. The mechanism of the inhibitory effect of the JQ1 and ingenol-B combination relative to ingenol-B alone was unclear but the effect appeared to be dose dependent. Conclusions Ingenol-B does not inhibit HIV-specific CD8+ T cell responses in vitro. These responses are however modestly inhibited when 100 nMingenol-B is combined with JQ1. Since HIV-specific CD8+ T cell activity may be essential for the eradication of reactivated latently infected cells, the potency of latency-reversal activity of drug combinations must be balanced against the effects of the combinations on HIV-specific CD8+ T cell responses.
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Affiliation(s)
- Abena K. Kwaa
- Center for AIDS Research, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Kennedy Goldsborough
- Center for AIDS Research, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Victoria E. Walker-Sperling
- Center for AIDS Research, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | | | - Lucio Gama
- Department of Molecular and Comparative Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Joel N. Blankson
- Center for AIDS Research, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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30
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Hoffman GE, Koban M. Hypothalamic L-Histidine Decarboxylase Is Up-Regulated During Chronic REM Sleep Deprivation of Rats. PLoS One 2016; 11:e0152252. [PMID: 27997552 PMCID: PMC5172538 DOI: 10.1371/journal.pone.0152252] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 03/11/2016] [Indexed: 12/20/2022] Open
Abstract
A competition of neurobehavioral drives of sleep and wakefulness occurs during sleep deprivation. When enforced chronically, subjects must remain awake. This study examines histaminergic neurons of the tuberomammillary nucleus of the posterior hypothalamus in response to enforced wakefulness in rats. We tested the hypothesis that the rate-limiting enzyme for histamine biosynthesis, L-histidine decarboxylase (HDC), would be up-regulated during chronic rapid eye movement sleep deprivation (REM-SD) because histamine plays a major role in maintaining wakefulness. Archived brain tissues of male Sprague Dawley rats from a previous study were used. Rats had been subjected to REM-SD by the flowerpot paradigm for 5, 10, or 15 days. For immunocytochemistry, rats were transcardially perfused with acrolein-paraformaldehyde for immunodetection of L-HDC; separate controls used carbodiimide-paraformaldehyde for immunodetection of histamine. Immunolocalization of histamine within the tuberomammillary nucleus was validated using carbodiimide. Because HDC antiserum has cross-reactivity with other decarboxylases at high antibody concentrations, titrations localized L-HDC to only tuberomammillary nucleus at a dilution of ≥ 1:300,000. REM-SD increased immunoreactive HDC by day 5 and it remained elevated in both dorsal and ventral aspects of the tuberomammillary complex. Our results suggest that up-regulation of L-HDC within the tuberomammillary complex during chronic REM-SD may be responsible for maintaining wakefulness.
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Affiliation(s)
- Gloria E. Hoffman
- Department of Biology, Morgan State University, Baltimore, Maryland, United States of America
| | - Michael Koban
- Department of Biology, Morgan State University, Baltimore, Maryland, United States of America
- * E-mail:
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