Biology subjects

REISER, J.-B.

Publications and source records attributed to REISER, J.-B..

3 recordsLinked to original sources

bioRxiv2026

Evidence for strong interplay between the nucleotide and base excision repair pathways in D. radiodurans

Deinococcus radiodurans harbors a largely classical bacterial DNA repair machinery yet displays exceptional resistance to ultra-violet and ionizing radiation. To investigate whether crosstalk between its DNA repair pathways contributes to this phenotype, we mapped putative interactions between the nucleotide excision repair (NER) and base excision repair (BER) pathways, which together are responsible for the removal of nucleobase lesions. Using a bacterial two-hybrid system, we identified multiple direct interactions between NER and BER proteins, notably involving the two UvrA variants, and validated these interactions in vitro. Furthermore, functional analyses revealed that NER interferes with the BER-mediated removal of oxidized guanines by the Fpg DNA glycosylase, likely through competition for DNA binding and sequestration of Fpg. Finally, UvrB and UvrC were found to further process the Fpg incision product in an ATP-dependent, UvrA1-independent manner. Together, these results demonstrate a multi-level crosstalk between NER and BER in D. radiodurans, which may contribute to its extraordinary DNA repair capacity. To our knowledge, this represents the first evidence of such a complex interplay in bacteria.

biochemistry↗

bioRxiv2024

The Fc fragment of soluble IgMs binds C1q to activate the classical complement pathway, while inhibiting complement-dependent cytotoxicity

Soluble type-M immunoglobulins (IgMs), among the most potent activators of the classical pathway, are key mediators of complement-dependent cytotoxicity, which render them promising drug candidates for the development of alternative drugs in treating autoimmune or inflammatory diseases. In this study, we investigated the biochemical and in vitro functional properties of recombinant fragments from IgMs corresponding to the Fc-core in their pentameric or hexameric forms. Biophysical experiments confirmed the crucial role of the IgM Joining chain (J) in favoring homogenous pentamers, while its absence led to heterogeneous population with a mixture of oligomeric forms. By combining size-exclusion chromatography with mass photometry, isolation of enriched samples with IgM hexamers or IgM pentamers without the J chain was possible. Biolayer interferometry demonstrated that both IgM-Fc forms bind C1q and ELISA showed that they induce the in vitro C4b deposition when in solid phase. Additionally, our data confirmed the higher efficacy of IgM hexamers compared to pentamers in activating the first component of the classical pathway. Finally, hemolytic assays demonstrate the ability of IgM-Fc constructs to inhibit Ig-induced complement-dependent cytotoxicity, which is likely made possible by the absence of Fab. These findings suggest a possible mechanism of C1 sequestration in plasma by IgM cores and consumption of the initial complement component C4. Our data thus provide important information for the development of IgM-based anti-inflammatory molecules that target specifically complement activation.

biochemistry↗

bioRxiv2021

Characterization of new recombinant Immunoglobulins type-M binding to C1q by Biolayer Interferometry

The Immunoglobulins type-M (IgMs) are one of the first antibody classes mobilized during immune responses against pathogens and tumor cells. Binding to specific target antigens enables the interaction with the C1 complex which strongly activates the classical complement pathway. This biological function is the basis for the huge therapeutic potential of IgMs but due to their high oligomeric complexity, in vitro production, biochemical and biophysical characterizations are challenging. In the present study, we present recombinant production of two IgM models (IgM617 and IgM012) in pentameric and hexameric states and the evaluation of their polymer distribution using different biophysical methods (AUC, SEC-MALLS, Mass Photometry and Transmission Electron Microscopy). Each IgM oligomer has individual specific expression pattern and yield with different protein quality likely due to intrinsic IgM properties and patterning. Nevertheless, the purified recombinant IgMs retain their ability to activate complement in a C1q dependent manner. And more importantly, a new method to evaluate their functional quality attribute by characterizing the kinetics of C1q binding to recombinant IgM has been developed using BioLayer Interferometry (BLI). We show that recombinant IgMs possess similar C1q binding properties as IgMs purified from human plasma.

bioengineering↗