The intrinsically disordered C-terminal peptide region of severe acute respiratory syndrome coronavirus 2 nonstructural protein-1 (Nsp1-CT) inhibits host protein synthesis by blocking messenger RNA (mRNA) access to the 40S ribosome entrance tunnel. Aqueous copper(II) ions bind to the disordered peptide with micromolar affinity, creating a possible strategy to restore protein synthesis during host infection. Electron paramagnetic resonance (EPR) and tryptophan fluorescence measurements on a 10-residue model of the disordered protein region (Nsp1-CT), combined with advanced quantum mechanics calculations, suggest that the peptide binds to copper(II) as a multidentate ligand. Two optimized computational models of the copper(II)-peptide complexes were derived: One corresponding to pH 6.5 and the other describing the complex at pH 7.5 to 8.5. Simulated EPR spectra based on the calculated model structures are in good agreement with experimental spectra.
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http://dx.doi.org/10.1073/pnas.2402653121 | DOI Listing |
Genetics
January 2025
Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Bloom Syndrome helicase (Blm) is a RecQ family helicase involved in DNA repair, cell-cycle progression, and development. Pathogenic variants in human BLM cause the autosomal recessive disorder Bloom Syndrome, characterized by predisposition to numerous types of cancer. Prior studies of Drosophila Blm mutants lacking helicase activity or protein have shown sensitivity to DNA damaging agents, defects in repairing DNA double-strand breaks (DSBs), female sterility, and improper segregation of chromosomes in meiosis.
View Article and Find Full Text PDFPolym Chem
August 2024
Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
While the conformational ensembles of disordered peptides and peptidomimetics are complex and challenging to characterize, they are a critical component in the paradigm connecting macromolecule sequence, structure, and function. In molecules that do not adopt a single predominant conformation, the conformational ensemble contains rich structural information that, if accessible, can provide a fundamental understanding related to desirable functions such as cell penetration of a therapeutic or the generation of tunable enzyme-mimetic architecture. To address the fundamental challenge of describing broad conformational ensembles, we developed a model system of peptidomimetics comprised of polar glycine and hydrophobic -butylglycine to characterize using a suite of analytical techniques.
View Article and Find Full Text PDFNat Struct Mol Biol
January 2025
Department of Biochemistry and Molecular Cell Biology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
The Rpd3S histone deacetylase complex has a crucial role in genomic integrity by deacetylating transcribed nucleosomes following RNA polymerase (Pol) II passage. Cryo-EM studies highlight the importance of asymmetrical Rco1-Eaf3 dimers in nucleosome binding, yet the interaction dynamics with nucleosomal substrates alongside elongating Pol II are poorly understood. Here we demonstrate the essential function of the Rco1 N-terminal intrinsically disordered region (IDR) in modulating Pol II association, in which K/R mutations within the Rco1 IDR impair interaction of Rpd3S with the C-terminal domain (CTD) of Rpb1, without affecting nucleosome recognition or complex integrity.
View Article and Find Full Text PDFNature
January 2025
Case Comprehensive Cancer Center and Department of Nutrition, Case Western Reserve University School of Medicine, Cleveland, OH, USA.
The oestrogen receptor (ER or ERα), a nuclear hormone receptor that drives most breast cancer, is commonly activated by phosphorylation at serine 118 within its intrinsically disordered N-terminal transactivation domain. Although this modification enables oestrogen-independent ER function, its mechanism has remained unclear despite ongoing clinical trials of kinase inhibitors targeting this region. By integration of small-angle X-ray scattering and nuclear magnetic resonance spectroscopy with functional studies, we show that serine 118 phosphorylation triggers an unexpected expansion of the disordered domain and disrupts specific hydrophobic clustering between two aromatic-rich regions.
View Article and Find Full Text PDFNucleic Acids Res
January 2025
Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
Serum response factor (SRF) is a master transcription factor that regulates immediate early genes and cytoskeletal remodeling genes. Despite its importance, the mechanisms through which SRF stably associates with its cognate promoter remain unknown. Our biochemical and protein-induced fluorescence enhancement analyses showed that the binding of SRF to serum response element was significantly increased by inositol polyphosphate multikinase (IPMK), an SRF cofactor.
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