Biology subjects

Waeytens, J.

Publications and source records attributed to Waeytens, J..

3 recordsLinked to original sources

bioRxiv2025

Unveiling the effect of phosphorylation on the structural and aggregation properties of the amyloidogenic intrinsically disordered protein DPF3a

The double plant homeodomain fingers 3a (DPF3 isoform a) is a human epigenetic regulator involved in chromatin remodelling, cell division, and ciliogenesis. Most notably, this protein is deregulated in various cancer types and neurodegenerative diseases. In our previous work, the disorder nature of DPF3a, as well as its propensity to aggregate into amyloid fibrils, have been highlighted, making it an amyloidogenic intrinsically disordered protein (IDP). Due to their high chain accessibility, IDPs structure and function are modulated by phosphorylation. It has been reported that phosphorylation of DPF3a at S348 (pS348) by the casein kinase 2 (CK2) is implicated in cardiac hypertrophy. CK2 can also phosphorylate DPF3a at S138 (pS138), which is also located in an intrinsically disordered region (IDR). However, no structural information is available on phosphorylated DPF3a. In the present study, we investigated the effect of phosphorylation on DPF3a structural and aggregation properties. Two single-mutated phosphomimetics (S138E and S348E) were characterised in vitro and compared to DPF3a WT, while in silico analyses were performed on pS138 and pS348 to assess structural changes at the molecular level. Circular dichroism and fluorescence spectroscopy revealed that both phosphomimetics are hybrid IDPs, with increased turn and antiparallel {beta}-sheet content as well as more buried aromatic residues compared to DPF3a WT, suggesting conformational rearrangements and a more folded N-terminal region. In silico characterisation supported these results, showing that phosphorylation of S138 and S348 induce extended conformation, especially the C-terminal extremity, due to electrostatic repulsion, while local folding occurs due to a proximity with arginine and lysine residues. Furthermore, spectroscopic and microscopic analyses unveiled that S138E and S348E exhibit slower fibrillation kinetics compared to DPF3a WT involving distinct aggregation mechanisms.

biophysics↗

bioRxiv2025

Synergistic Action of Commercial Lipase, Lipoxygenases and Proteinase towards PLA Depolymerization

Polylactic acid (PLA) is a biobased aliphatic polyester produced from renewable resources. Its building block is lactic acid (LA), which is mainly produced through fermentation processes rather than chemical synthesis, as fermentation enables the production of optically pure D-LA or L-LA, instead of a racemic mixture. In this work, three commercial enzymes Proteinase K (PrK) from Tritirachium album, Candida rugosa lipase (CrLip), and Glycine max lipoxygenase (LOX I-B) were investigated for their synergistic action for the degradation of solvent-cast as well as EoL-PLA films. While Lip and LOX I-B alone did not promote PLA hydrolysis, they significantly enhanced PrK-mediated hydrolysis by 5.7-fold and 2.5-fold, respectively. Lip, and to a lesser extent LOX I-B, increased PrKs productive binding to the polymer, thus accelerating catalysis. These findings underline the potential of synergistic enzymes for PLA degradation and provide the first evidence of lipoxygenase activity in this process.

biochemistry↗

bioRxiv2021

Plastic biodegradation: do Galleria mellonella larvae - bio-assimilate polyethylene? A spectral histology approach using isotopic labelling and infrared microspectroscopy.

Environmental pollution by non-biodegradable polyethylene (PE) plastics is of major concern, thus, organisms capable of bio-degrading PE are required. The larvae of the Greater Wax Moth, Galleria mellonella (Gm), were identified as a potential candidate to digest PE. In this study, we tested whether PE was metabolized by Gm larvae and could found in their tissues. We examined the implication of the larval gut microbiota by using conventional and axenic reared insects. First, our study showed that neither beeswax nor PE alone favour the growth of young larvae. We then used Fourier-Transform Infrared Microspectroscopy ({micro}FTIR) to detect deuterium in larvae fed with isotopically labelled food. Perdeuterated molecules were found in most tissues of larvae fed with deuterium labelled oil for 72 hours proving that {micro}FTIR can detect metabolization of 1-2 mg of deuterated food. No bio-assimilation was detected in the tissues of larvae fed with 1-5 mg of perdeuterated PED4 for 72 hours and 19-21 days, but micron sized PE particles were found in the larval digestive tract cavities. We evidenced weak bio-degradation of PE films in contact for 24 hours with the dissected gut of conventional larvae; and in the PED4 particles from excreted larval frass. Our study confirms that Gm larvae can bio-degrade PE but can not necessarily metabolize it.

ecology↗