Biology subjects

Drzewicka, K.

Publications and source records attributed to Drzewicka, K..

4 recordsLinked to original sources

bioRxiv2024

Mechanism of catalytic apparatus of human chitotriosidase-1 and its dual inactivation mode by the first-in-class OATD-01 inhibitor.

Despite extensive research over the past three decades, there are still uncertainties regarding the catalytic mechanism of human chitotriosidase-1. To fill the gap, we reanalysed the structural information available for this enzyme. Based on the existing and new experimental data, complemented by multi-scale simulations, we modelled the full-length structure of human chitotriosidase-1 and proposed the general model of its catalytic mechanism. We have elucidated the catalytic role of the four highly conserved structural motifs present in glycoside hydrolases 18 family and demonstrated the impact of ions on achieving optimal catalytic conditions. Furthermore, we have identified distinct mechanical motions within the catalytic domain that collectively facilitate the catalysis. Finally, we demonstrate how subtle dynamical changes observed within the active site upon binding of the OATD-01 inhibitor correspond to long-range effects that are transmitted across enzyme subunits, leading to profound biological consequences.

biophysics↗

bioRxiv2024

Chitinase-1 inhibition reverses metabolic dysregulation and restores homeostasis in MASH animal models

OATD-01 is a chitinase-1 (CHIT1) inhibitor, reducing inflammation and fibrosis in animal models where chronic inflammation leads to tissue remodeling. CHIT1, predominantly secreted by macrophages, is overexpressed in metabolic-dysfunction-associated steatohepatitis (MASH). In this study, we demonstrated the efficacy of OATD-01 in two murine and a rat model of MASH. RNA-Seq analysis revealed that OATD-01 reversed MASH-dysregulated genes. Apart from the attenuation of inflammation and fibrosis, OATD-01 regulated metabolic processes such as lipid metabolism and glycolysis. We demonstrated that both genetic and pharmacological inactivation of CHIT1 resulted in inhibition of glycolysis and glucose uptake in primary macrophages. As a consequence, we observed increased ATP, lower citrate and increased acetate levels, resulting in a reduced IL-1{beta} secretion. These results revealed the key role for CHIT1 in regulating metabolism. OATD-01 is a macrophage modulator that can directly restore metabolic balance and consequently inhibit inflammation and fibrosis, supporting its use for MASH treatment.

pharmacology and toxicology↗

bioRxiv2020

Hsf1 is SUMOylated in the activated trimeric state

The heat shock response (HSR) is a transcriptional program of organisms to counteract an imbalance in protein homeostasis. It is orchestrated in all eukaryotic cells by heat shock factor 1 (Hsf1). Despite very intensive research, the intricacies of the Hsf1 activation-attenuation cycle remain elusive at a molecular level. Posttranslational modifications belong to one of the key mechanisms proposed to adapt the Hsf1 activity to the needs of individual cells and phosphorylation of Hsf1 at multiple sites has attracted much attention. According to cell biological and proteomics data, Hsf1 is also modified by SUMO (small ubiquitin-like modifier) at several sites. How SUMOylation affects Hsf1 activity at a molecular level is still unclear. Here, we analyzed Hsf1 SUMOylation in vitro with purified components to address questions that could not be answered in cell culture models. In vitro Hsf1 is primarily conjugated at lysine 298 with a single SUMO, though we did detect low level SUMOylation at other sites. None of the tested E3 SUMO ligases increased SUMOylation efficacy as compared to the level in the presence of high concentrations of the E2 Ubc9. We provide evidence that Hsf1 trimerization and phosphorylation at serines 303 and 307 increases SUMOylation efficiency, suggesting that Hsf1 is SUMOylated in its activated state. Hsf1 can be SUMOylated when DNA-bound, and SUMOylation of Hsf1 does neither alter DNA binding affinity nor does it affect Hsc70 and DnaJB1-mediated monomerization of Hsf1 trimers and concomitant dislocation from DNA. We propose that SUMOylation acts at the transcription level of the HSR.

biochemistry↗

bioRxiv2018

Pyrophosphate modulates stress responses via SUMOylation

Pyrophosphate (PPi), a byproduct of macromolecule biosynthesis is maintained at low levels by soluble inorganic pyrophosphatases (sPPase) found in all eukaryotes. In plants, H+-pumping pyrophosphatases (H+-PPase) convert the substantial energy present in PPi into an electrochemical gradient. We show here, that both cold- and heat stress sensitivity of fugu5 mutants lacking the major H+-PPase isoform AVP1 is caused by reduced SUMOylation. In addition, we show that increased PPi concentrations interfere with SUMOylation in yeast and we provide evidence that SUMO activating E1-enzymes are inhibited by micromolar concentrations of PPi in a non-competitive manner. Taken together, our results do not only provide a mechanistic explanation for the beneficial effects of AVP1 overexpression in plants but they also highlight PPi as an important integrator of metabolism and stress tolerance.

biochemistry↗