Wednesday, February 28, 2018

BioJava-ModFinder: identification of protein modifications in 3D structures from the Protein Data Bank

Jianjiong Gao  Andreas Prlić  Chunxiao Bi  Wolfgang F. Bluhm  Dimitris Dimitropoulos Dong Xu  Philip E. Bourne  Peter W. Rose  

Bioinformatics, 2017,  2047–2049,
https://doi.org/10.1093/bioinformatics/btx101

We developed a new software tool, BioJava-ModFinder, for identifying protein modifications observed in 3D structures archived in the Protein Data Bank (PDB). Information on more than 400 types of protein modifications were collected and curated from annotations in PDB, RESID, and PSI-MOD. We divided these modifications into three categories: modified residues, attachment modifications, and cross-links. We have developed a systematic method to identify these modifications in 3D protein structures. We have integrated this package with the RCSB PDB web application and added protein modification annotations to the sequence diagram and structure display. By scanning all 3D structures in the PDB using BioJava-ModFinder, we identified more than 30 000 structures with protein modifications, which can be searched, browsed, and visualized on the RCSB PDB website.
Protein modifications mapped onto the sequence and structure of ferredoxin I (PDB ID 1GAO, Chen et al., 2002). The Protein Modification track highlights residues involved in two iron-sulfur clusters (3Fe-4S (F3S): triangles/lines and 4Fe-4S (SF4): diamonds/lines). The number of edges of the protein modification icon symbolizes the number of residues involved in the modification. The 4Fe-4S cluster is displayed in the Jmol structure window above the sequence display

Tuesday, February 27, 2018

SRPKIN-1: A Covalent SRPK1/2 Inhibitor that Potently Converts VEGF from Pro-angiogenic to Anti-angiogenic Isoform Author links open overlay panel


The SRPK family of kinases regulates pre-mRNA splicing by phosphorylating serine/arginine (SR)-rich splicing factors, signals splicing control in response to extracellular stimuli, and contributes to tumorigenesis, suggesting that these splicing kinases are potential therapeutic targets. Here, we report the development of the first irreversible SRPK inhibitor, SRPKIN-1, which is also the first kinase inhibitor that forms a covalent bond with a tyrosine phenol group in the ATP-binding pocket. Kinome-wide profiling demonstrates its selectivity for SRPK1/2, and SRPKIN-1 attenuates SR protein phosphorylation at submicromolar concentrations. Vascular endothelial growth factor (VEGF) is a known target for SRPK-regulated splicing and, relative to the first-generation SRPK inhibitor SRPIN340 or small interfering RNA-mediated SRPK knockdown, SRPKIN-1 is more potent in converting the pro-angiogenic VEGF-A165a to the anti-angiogenic VEGF-A165b isoform and in blocking laser-induced neovascularization in a murine retinal model. These findings encourage further development of SRPK inhibitors for treatment of age-related macular degeneration.

Saturday, February 17, 2018

2‑Formylpyridyl Ureas as Highly Selective Reversible-Covalent Inhibitors of Fibroblast Growth Factor Receptor 4

Thomas Knoepfel, Pascal Furet, Robert Mah, Nicole Buschmann, Catherine Leblanc, Sebastien Ripoche, Diana Graus-Porta, Markus Wartmann, Inga Galuba, and Robin A. Fairhurst

ACS Med. Chem. Lett., Article ASAP
DOI: 10.1021/acsmedchemlett.7b00485

 As part of a project to identify FGFR4 selective inhibitors, scaffold morphing of a 2-formylquinoline amide hit identified series of 2-formylpyridine ureas (2-FPUs) with improved potency and physicochemical properties. In particular, tetrahydronaphthyridine urea analogues with cellular activities below 30 nM have been identified. Consistent with the hypothesized reversible-covalent mechanism of inhibition, the 2-FPUs exhibited slow binding kinetics, and the aldehyde, as the putative electrophile, could be demonstrated to be a key structural element for activity.

L718Q mutant EGFR escapes covalent inhibition by stabilizing a non-reactive conformation of the lung cancer drug osimertinib

D. Callegari, K. E. Ranaghan, C. J. Woods, R. Minari, M. Tiseo, M. Mor, A. J. Mulholland, and A. Lodola

Chem. Sci., 2018
DOI: 10.1039/C7SC04761D

Osimertinib is a third-generation inhibitor approved for the treatment of non-small cell lung cancer. It overcomes resistance to first-generation inhibitors by incorporating an acrylamide group which alkylates Cys797 of EGFR T790M. The mutation of a residue in the P-loop (L718Q) was shown to cause resistance to osimertinib, but the molecular mechanism of this process is unknown. Here, we investigated the inhibitory process for EGFR T790M (susceptible to osimertinib) and EGFR T790M/L718Q (resistant to osimertinib), by modelling the chemical step (i.e., alkylation of Cys797) using QM/MM simulations and the recognition step by MD simulations coupled with free-energy calculations. The calculations indicate that L718Q has a negligible impact on both the activation energy for Cys797 alkylation and the free-energy of binding for the formation of the non-covalent complex. The results show that Gln718 affects the conformational space of the EGFR–osimertinib complex, stabilizing a conformation of acrylamide which prevents reaction with Cys797.

Thiol Reactivity of N-Aryl α-Methylene-γ-lactams: Influence of the Guaianolide Structure [@KayBrummond]

 Daniel P. Dempe, Chong-Lei Ji, Peng Liu, and Kay M. Brummond The Journal of Organic Chemistry, 2020 DOI: 10.1021/acs.joc.2c01530 The α-meth...