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1.
Int J Mol Sci ; 22(13)2021 Jun 25.
Article in English | MEDLINE | ID: covidwho-1304663

ABSTRACT

Our understanding of the structure-function relationships of biomolecules and thereby applying it to drug discovery programs are substantially dependent on the availability of the structural information of ligand-protein complexes. However, the correct interpretation of the electron density of a small molecule bound to a crystal structure of a macromolecule is not trivial. Our analysis involving quality assessment of ~0.28 million small molecule-protein binding site pairs derived from crystal structures corresponding to ~66,000 PDB entries indicates that the majority (65%) of the pairs might need little (54%) or no (11%) attention. Out of the remaining 35% of pairs that need attention, 11% of the pairs (including structures with high/moderate resolution) pose serious concerns. Unfortunately, most users of crystal structures lack the training to evaluate the quality of a crystal structure against its experimental data and, in general, rely on the resolution as a 'gold standard' quality metric. Our work aims to sensitize the non-crystallographers that resolution, which is a global quality metric, need not be an accurate indicator of local structural quality. In this article, we demonstrate the use of several freely available tools that quantify local structural quality and are easy to use from a non-crystallographer's perspective. We further propose a few solutions for consideration by the scientific community to promote quality research in structural biology and applied areas.


Subject(s)
Binding Sites , Ligands , Macromolecular Substances/chemistry , Models, Molecular , Proteins/chemistry , Crystallography, X-Ray , Macromolecular Substances/metabolism , Molecular Conformation , Protein Binding , Proteins/metabolism
2.
Nat Commun ; 12(1): 3399, 2021 06 07.
Article in English | MEDLINE | ID: covidwho-1260942

ABSTRACT

Structures of macromolecular assemblies derived from cryo-EM maps often contain errors that become more abundant with decreasing resolution. Despite efforts in the cryo-EM community to develop metrics for map and atomistic model validation, thus far, no specific scoring metrics have been applied systematically to assess the interface between the assembly subunits. Here, we comprehensively assessed protein-protein interfaces in macromolecular assemblies derived by cryo-EM. To this end, we developed Protein Interface-score (PI-score), a density-independent machine learning-based metric, trained using the features of protein-protein interfaces in crystal structures. We evaluated 5873 interfaces in 1053 PDB-deposited cryo-EM models (including SARS-CoV-2 complexes), as well as the models submitted to CASP13 cryo-EM targets and the EM model challenge. We further inspected the interfaces associated with low-scores and found that some of those, especially in intermediate-to-low resolution (worse than 4 Å) structures, were not captured by density-based assessment scores. A combined score incorporating PI-score and fit-to-density score showed discriminatory power, allowing our method to provide a powerful complementary assessment tool for the ever-increasing number of complexes solved by cryo-EM.


Subject(s)
Cryoelectron Microscopy/methods , Macromolecular Substances/chemistry , Protein Interaction Domains and Motifs , Protein Interaction Mapping/methods , Protein Interaction Maps , Proteins/chemistry , Humans , Machine Learning , Macromolecular Substances/metabolism , Macromolecular Substances/ultrastructure , Models, Molecular , Neural Networks, Computer , Protein Conformation , Protein Multimerization , Proteins/metabolism , Proteins/ultrastructure , Support Vector Machine , Viral Nonstructural Proteins/chemistry , Viral Nonstructural Proteins/metabolism , Viral Nonstructural Proteins/ultrastructure
3.
Angew Chem Int Ed Engl ; 60(33): 18144-18151, 2021 08 09.
Article in English | MEDLINE | ID: covidwho-1206743

ABSTRACT

The untranslated regions (UTRs) of viral genomes contain a variety of conserved yet dynamic structures crucial for viral replication, providing drug targets for the development of broad spectrum anti-virals. We combine in vitro RNA analysis with molecular dynamics simulations to build the first 3D models of the structure and dynamics of key regions of the 5' UTR of the SARS-CoV-2 genome. Furthermore, we determine the binding of metallo-supramolecular helicates (cylinders) to this RNA structure. These nano-size agents are uniquely able to thread through RNA junctions and we identify their binding to a 3-base bulge and the central cross 4-way junction located in stem loop 5. Finally, we show these RNA-binding cylinders suppress SARS-CoV-2 replication, highlighting their potential as novel anti-viral agents.


Subject(s)
5' Untranslated Regions , Antiviral Agents/pharmacology , Macromolecular Substances/pharmacology , RNA/metabolism , SARS-CoV-2/drug effects , Virus Replication/drug effects , Animals , Antiviral Agents/chemistry , Antiviral Agents/metabolism , Chlorocebus aethiops , Coordination Complexes/chemistry , Coordination Complexes/metabolism , Coordination Complexes/pharmacology , Genome, Viral/drug effects , Macromolecular Substances/chemistry , Macromolecular Substances/metabolism , Metals, Heavy/chemistry , Molecular Dynamics Simulation , RNA/genetics , SARS-CoV-2/chemistry , Vero Cells
4.
Nucleic Acids Res ; 49(D1): D437-D451, 2021 01 08.
Article in English | MEDLINE | ID: covidwho-936421

ABSTRACT

The Research Collaboratory for Structural Bioinformatics Protein Data Bank (RCSB PDB), the US data center for the global PDB archive and a founding member of the Worldwide Protein Data Bank partnership, serves tens of thousands of data depositors in the Americas and Oceania and makes 3D macromolecular structure data available at no charge and without restrictions to millions of RCSB.org users around the world, including >660 000 educators, students and members of the curious public using PDB101.RCSB.org. PDB data depositors include structural biologists using macromolecular crystallography, nuclear magnetic resonance spectroscopy, 3D electron microscopy and micro-electron diffraction. PDB data consumers accessing our web portals include researchers, educators and students studying fundamental biology, biomedicine, biotechnology, bioengineering and energy sciences. During the past 2 years, the research-focused RCSB PDB web portal (RCSB.org) has undergone a complete redesign, enabling improved searching with full Boolean operator logic and more facile access to PDB data integrated with >40 external biodata resources. New features and resources are described in detail using examples that showcase recently released structures of SARS-CoV-2 proteins and host cell proteins relevant to understanding and addressing the COVID-19 global pandemic.


Subject(s)
Computational Biology/methods , Databases, Protein , Macromolecular Substances/chemistry , Protein Conformation , Proteins/chemistry , Bioengineering/methods , Biomedical Research/methods , Biotechnology/methods , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19/virology , Humans , Macromolecular Substances/metabolism , Pandemics , Proteins/genetics , Proteins/metabolism , SARS-CoV-2/genetics , SARS-CoV-2/metabolism , SARS-CoV-2/physiology , Software , Viral Proteins/chemistry , Viral Proteins/genetics , Viral Proteins/metabolism
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