Biology subjects

Grygier, P.

Publications and source records attributed to Grygier, P..

4 recordsLinked to original sources

bioRxiv2025

Crystallographic characterisation and development of bi-substrate inhibitors of coronavirus nsp14 methyltransferase

SARS-CoV-2 non-structural protein 14 (nsp14) is essential for viral mRNA cap guanine-N7 methylation and represents a promising but underexplored antiviral target. Herein we describe a structure-guided campaign based on a hit from a focussed SAM mimetic library. Systematic SAR exploration guided by six X-ray co-crystal structures in complex with SARS-CoV-2 led to compound 26, a bi-substrate inhibitor that bridges the SAM and RNA cap binding sites. Compound 26 achieved nanomolar potency against nsp14 from SARS-CoV-2 (IC50 = 53 nM), SARS-CoV-1, and two alphacoronaviruses, with excellent selectivity over human RNMT and flaviviral MTase. In general, the compounds demonstrated favourable metabolic stability, passive permeability, and no HepG2 cytotoxicity. However, cellular antiviral activity was limited, revealing disconnects between enzyme inhibition and phenotypic response. These findings provide a structural framework for optimizing bi-substrate methyltransferase inhibitors against coronaviruses with a view for pan-coronaviral activity.

biochemistry↗

bioRxiv2025

Revealing the unexpected interplay between the Proteasome Activator PA200 and the immunoproteasome

The proteasome activator PA200 binds to the catalytic core of the proteasome, the 20S, and activates its proteolytic activities. The cellular function of PA200 is poorly understood and appears to be cell type and differentiation specific. Recent evidence suggests that PA200 not only binds to the standard 20S (s20S) proteasome but also to the specialized immunoproteasome (i20S) which plays a key role in anti-viral and anti-tumor immunity. We here investigated the interaction of PA200 and the immunoproteasome in detail. We show the very first cryo-EM structures of the singly- and doubly-capped i20S-PA200 complexes that revealed no major difference regarding the first binding event of PA200 to the i20S vs. the s20S. However, first PA200 binding triggered a subtle and long range allosteric bending of the i20S barrel which was not seen in the s20S-PA200 complexes. This resulted in major structural rearrangements in the opposite unbound ring - the displacement of atoms up to 5.4 [A] and the increase in its outer diameter - thereby increasing the occupancy of the second PA200 binding site. Mass photometry confirmed higher occupancy of PA200 to the i20S versus the s20S. Binding of PA200 to the i20S enhanced proteasomal activation compared to the s20S. Co-expression of PA200 and the i20S in cells and tissues, however, is restricted but their interaction is favored upon co-expression. The expression of PA200 and the catalytic subunits of the i20S is differentially regulated depending on the cellular context. Our data also suggest that PA200 has the potential to regulate i20S gene expression whereas the i20S has no effects on PA200 expression. Overall, this work sheds new light on the interaction of PA200 with the i20S from a structural, mechanistic and cellular point of view. Importantly, we identify PA200 as a key regulator of the i20S whenever PA200 and the catalytic subunits of the i20S are co-expressed in the same cell.

biochemistry↗

bioRxiv2024

Curcumin Inhibition of DYRK Kinases

Curcumin is known as a dietary supplement with several health benefits, including antioxidant, blood sugar-lowering, anti-inflammatory, and anti-cancer properties. These benefits make it useful in the treatment of diabetes, neurodegenerative diseases, and cancer. This research focuses on how curcumin interacts with dual-specificity tyrosine-regulated kinases (DYRKs), particularly DYRK1A and DYRK2, which control important cellular processes such as protein breakdown, gene activity and DNA packaging. DYRK1A is crucial for the growth and survival of pancreatic {beta}-cells, which are key in the treatment of diabetes. Curcumin helps increase insulin release and sensitivity by affecting these cells. DYRK2, on the other hand, is involved in cancer, where curcumins ability to block its activity helps to reduce tumour growth and spread. These interactions demonstrate curcumins potential as a versatile treatment option. By affecting DYRK1A and DYRK2, curcumin promotes {beta}-cell health in diabetes and fights cancer by inhibiting cell growth and promoting cell death. This study underscores the promise of curcumin as a natural compound for treating complex diseases associated with oxidative stress and inflammation, highlighting the need for a better understanding of DYRK kinases to effectively exploit their role in disease processes and cell signalling.

molecular biology↗

bioRxiv2022

Structural perspective on the design of selective DYRK1B inhibitors.

DYRK1B has been recently recognized as a critical therapeutic target in oncology and non-alcoholic fatty liver disease. However, the lack of structural information has constrained the development of selective inhibitors for DYRK1B. Here, we employed recombinant protein production, activity assays, and crystallization to elucidate the structure of DYRK1B. We present a crystal structure of DYRK1B in complex with a known inhibitor, AZ191. For comparative analysis, we provide the crystal structure of the closely related DYRK1A kinase in complex with AZ191. Our analysis identifies the exclusiveness of the binding site in the hinge region of DYRK1B, which is pivotal for selective inhibitor design. Quantum mechanical calculations reveal a notable difference in the accessibility of the catalytic lysine between DYRK1B and DYRK1A, offering avenues for distinguishing binders to these kinases. Our findings mark a significant advancement in the quest for specific DYRK1B inhibitors, potentially offering focused efficacy compared to the current dual-specificity inhibitors targeting both DYRK1B and DYRK1A.

biochemistry↗