Structural insights into non-hotspot KRAS mutations and their potential as targets for effective cancer therapies

Kirsten rat sarcoma virus protein (KRAS) is a protein that plays a central role in signal transduction using extracellular signal regulated kinase (ERK) and mitogen activated protein kinase (MAPK) cellular signaling pathway. KRAS is a frequently mutated oncogene and plays a pivotal role in tumor initiation and progression. Hotspot mutations on codon 12, 13 and 61 in KRAS are well-known for their role in drug resistance and non-hotspot mutations also play a significant part in contributing to resistance mechanisms. The understanding of how these non-hotspot mutations might affect the signal transduction of KRAS and their contribution towards drug resistance is understudied. Here we provide structural insights into the interaction of non-hotspot KRAS mutants with GTP (the native ligand) using a molecular docking and molecular dynamics simulation approach. Extensive molecular docking and simulation studies suggest that non-hotspot mutations (E31D and E63K) show stable interaction with native ligand using all five trajectories, as evidenced by root mean square of distance (RMSD), root mean square of fluctuation (RMSF), radius of gyration (RoG), coulomb short-range energy and MMGBSA analysis. These results suggest that non-hotspot mutations do not undermine the oncogenic nature of KRAS. This observation is consistent with previous findings where overexpressing E31D and E63K mutations share phenotypic features with G12D and G13D transfected cells, including increased proliferative capacity, actin cytoskeleton organization, and migration rates. We further test whether FDA-approved KRAS inhibitors sotorasib and adagrasib successfully inhibit the E31D and E63K mutants. Results suggest that these two non-hotspot mutants can be inhibited by both drugs with following trend of structural stability (E31D > E63K > wild-KRAS > Q61H > G12C). Based on sharp coherence in trajectories between wild KRAS and non-hotspot mutants, it is suggested that these novel mutants do not contribute to drug resistance mechanism. Overall, we provide a comprehensive understanding of the impact of non-hotspot mutations on KRAS and their potential as targets for effective cancer therapies. Communicated by Ramaswamy H. Sarma</p

Depolymerization of Lignin to Aromatics by Selectively Oxidizing Cleavage of C–C and C–O Bonds Using CuCl₂/Polybenzoxazine Catalysts at Room Temperature

A novel strategy for the oxidative cleavage of C–C and C–O bonds in a series of model substrates including β-O-4 lignin model compounds using CuCl₂/polybenzoxazine composites catalysts with H₂O₂ as oxidant at room temperature showed good conversions (up to 88%) and an over 96% total selectivity to aromatic monomers within 2 h. This approach then succeeded in application to actual lignin depolymerization monitored by gel permeation chromatography (GPC), ¹H NMR, and 2D-NMR (HSQC). The results suggest that lignin can be effectively degraded into an array of functionalized dimer–trimeric aromatic acids, aldehydes, phenols, etc., obtained from the selective cleavage of aliphatic C–C and C–O bonds in the major linkages β-O-4′ aryl ethers, resinols, and <i>p</i>-hydroxycinnamyl alcohols while leaving the natural aromaticity intact. Furthermore, the mechanistic insights into the catalytic reactions reveal a two-electron transfer process involved with a phenoxy radical, and an oxidation-then-cleavage route proposed for lignin depolymerization. The clean process, mild reaction conditions, and high aromatics selectivity indicate that it is a promising heterogeneous catalytic system for oxidative depolymerization of lignin to valuable aromatic chemicals

Small Unnatural Amino Acid Carried Raman Tag for Molecular Imaging of Genetically Targeted Proteins

Raman has been implemented to image biological systems for decades. However, Raman microscopy along with Raman probes is restricted to image metabolites or a few intracellular organelles so far and lacks genetic specificity for imaging proteins of interest, which significantly hinders their application. Here, we report the Raman spectra-based protein imaging method, which incorporates a small phenyl ring enhanced Raman tag (total of ∼0.55 kDa) with a single unnatural amino acid (UAA) to genetically label specific proteins. We further demonstrate hyperspectral stimulated Raman scattering (SRS) imaging of the Histone3.3 protein in the nucleus, Sec61β protein in the endoplasmic reticulum of HeLa cells, and Huntingtin protein Htt74Q in mutant huntingtin-induced cells. Genetic encoding of a small, stable, sensitive, and narrow-band Raman tag took one key step forward to enable SRS or Raman imaging of specific proteins and could further facilitate quantitative Raman spectra-based supermultiplexing microscopy in the future

Small Unnatural Amino Acid Carried Raman Tag for Molecular Imaging of Genetically Targeted Proteins

Raman has been implemented to image biological systems for decades. However, Raman microscopy along with Raman probes is restricted to image metabolites or a few intracellular organelles so far and lacks genetic specificity for imaging proteins of interest, which significantly hinders their application. Here, we report the Raman spectra-based protein imaging method, which incorporates a small phenyl ring enhanced Raman tag (total of ∼0.55 kDa) with a single unnatural amino acid (UAA) to genetically label specific proteins. We further demonstrate hyperspectral stimulated Raman scattering (SRS) imaging of the Histone3.3 protein in the nucleus, Sec61β protein in the endoplasmic reticulum of HeLa cells, and Huntingtin protein Htt74Q in mutant huntingtin-induced cells. Genetic encoding of a small, stable, sensitive, and narrow-band Raman tag took one key step forward to enable SRS or Raman imaging of specific proteins and could further facilitate quantitative Raman spectra-based supermultiplexing microscopy in the future

Small Unnatural Amino Acid Carried Raman Tag for Molecular Imaging of Genetically Targeted Proteins

Raman has been implemented to image biological systems for decades. However, Raman microscopy along with Raman probes is restricted to image metabolites or a few intracellular organelles so far and lacks genetic specificity for imaging proteins of interest, which significantly hinders their application. Here, we report the Raman spectra-based protein imaging method, which incorporates a small phenyl ring enhanced Raman tag (total of ∼0.55 kDa) with a single unnatural amino acid (UAA) to genetically label specific proteins. We further demonstrate hyperspectral stimulated Raman scattering (SRS) imaging of the Histone3.3 protein in the nucleus, Sec61β protein in the endoplasmic reticulum of HeLa cells, and Huntingtin protein Htt74Q in mutant huntingtin-induced cells. Genetic encoding of a small, stable, sensitive, and narrow-band Raman tag took one key step forward to enable SRS or Raman imaging of specific proteins and could further facilitate quantitative Raman spectra-based supermultiplexing microscopy in the future

Co Nanoparticles/Co, N, S Tri-doped Graphene Templated from In-Situ-Formed Co, S Co-doped g‑C₃N₄ as an Active Bifunctional Electrocatalyst for Overall Water Splitting

The development of high-performance electrocatalyst with earth-abundant elements for water-splitting is a key factor to improve its cost efficiency. Herein, a noble metal-free bifunctional electrocatalyst was synthesized by a facile pyrolysis method using sucrose, urea, Co­(NO₃)₂ and sulfur powder as raw materials. During the fabrication process, Co, S co-doped graphitic carbon nitride (g-C₃N₄) was first produced, and then this in-situ-formed template further induced the generation of a Co, N, S tri-doped graphene coupled with Co nanoparticles (NPs) in the following pyrolysis process. The effect of pyrolysis temperature (700, 800, and 900 °C) on the physical properties and electrochemical performances of the final product was studied. Thanks to the increased number of graphene layer encapsulated Co NPs, higher graphitization degree of carbon matrix and the existence of hierarchical macro/meso pores, the composite electrocatalyst prepared under 900 °C presented the best activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with outstanding long-term durability. This work presented a facile method for the fabrication of non-noble-metal-based carbon composite from in-situ-formed template and also demonstrated a potential bifunctional electrocatalyst for the future investigation and application

Facile Synthesis of Carbon-Coated Spinel Li₄Ti₅O₁₂/Rutile-TiO₂ Composites as an Improved Anode Material in Full Lithium-Ion Batteries with LiFePO₄@N-Doped Carbon Cathode

The spinel Li₄Ti₅O₁₂/rutile-TiO₂@carbon (LTO-RTO@C) composites were fabricated via a hydrothermal method combined with calcination treatment employing glucose as carbon source. The carbon coating layer and the in situ formed rutile-TiO₂ can effectively enhance the electric conductivity and provide quick Li⁺ diffusion pathways for Li₄Ti₅O₁₂. When used as an anode material for lithium-ion batteries, the rate capability and cycling stability of LTO-RTO@C composites were improved in comparison with those of pure Li₄Ti₅O₁₂ or Li₄Ti₅O₁₂/rutile-TiO₂. Moreover, the potential of approximately 1.8 V rechargeable full lithium-ion batteries has been achieved by utilizing an LTO-RTO@C anode and a LiFePO₄@N-doped carbon cathode