Czermak, P. | Search bioRxiv

bioRxiv2026

Multi-dimensional optimization of a lysin towards a ribolysin against life-threatening S. aureus infections: Fc-LysM-CHAP and its strong synergy with standard of care antibiotics

Bacterial lysins are promising novel antimicrobials but are limited by poor pharmacokinetics and challenging manufacturability. We developed a lysin discovery platform tailored for lysin delivery via mRNA: staphylococcal LysM-CHAP (cysteine, histidine-dependent amidohydrolases/peptidase) autolysin was selected and its serum half-life extended via Immunoglobulin G1-Fc-fusion. The Fc-induced drop in lysin potency was rescued by the concerted optimization of linkers, binding kinetics and catalytic activity, using a combination of rational and AI-guided approaches. The engineered Fc-LysM-CHAP was active against planktonic bacteria (minimum inhibitory concentration of 1 - 2 {micro}g/mL) and simulated endocardial vegetations and synergized strongly (Fractional eradication concentration index FECI = 0.06) with cell wall active antibiotics in vitro. In mouse models of Staphylococcus aureus sepsis, the recombinant Fc-LysM-CHAP - antibiotic combination was superior to single agent treatments and mRNA-delivered Fc-LysM-CHAP showed single agent activity at a mRNA-lipid nanoparticle dose as low as 0.2 mg/kg.

microbiology↗

bioRxiv2022

Composition can buffer protein dynamics within liquid-like condensates.

Most non-membrane-bound compartments in cells that form via phase separation have complex composition. While phase separation of individual proteins that form these compartments is well-documented, the mechanisms that modulate dynamics of individual proteins in multicomponent systems remain unclear. Here, we used in vitro reconstitution and in vivo experiments to investigate how the dynamics of a scaffold protein PGL-3 is regulated within the liquid-like P granule compartment in C. elegans. Using mutational and biophysical perturbations, we generated PGL-3 constructs that form condensates in vitro with widely varying dynamics. Using these PGL-3 constructs, we show that introducing other P granule components buffers against change of dynamics within liquid-like condensates. This dynamics-buffering effect is mediated by weak interactions among two or more components. Such dynamics-buffering may contribute to robust functional output of cellular liquid-like compartments.

cell biology↗