Decoupling Fluorous Protein Coatings Yield Heat-Stable and Intrinsically Sterile Bioformulations.

Thermal inactivation is a major bottleneck to the scalable production, storage, and transportation of protein-based reagents and therapies. Failures in temperature control both compromise protein bioactivity and increase the risk of microorganismal contamination. Herein, we report the rational design of fluorochemical additives that promiscuously bind to and coat the surfaces of proteins to enable their stable dispersion within fluorous solvents. By replacing traditional aqueous liquids with fluorinated media, this strategy conformationally rigidifies proteins to preserve their structure and function at extreme temperatures (≥90 °C). We show that fluorous protein formulations resist contamination by bacterial, fungal, and viral pathogens, which require aqueous environments for survival, and display equivalent serum bioavailability to standard saline samples in animal models. Importantly, by designing dispersants that decouple from the protein surface in physiologic solutions, we deliver a fluorochemical formulation that does not alter the pharmacologic function or safety profile of the functionalized protein in vivo. As a result, this nonaqueous protein storage paradigm is poised to open technological opportunities in the design of shelf-stable protein reagents and biopharmaceuticals.

The Multifaceted Bacterial Cysteine Desulfurases: From Metabolism to Pathogenesis.

Living cells have developed a relay system to efficiently transfer sulfur (S) from cysteine to various thio-cofactors (iron-sulfur (Fe-S) clusters, thiamine, molybdopterin, lipoic acid, and biotin) and thiolated tRNA. The presence of such a transit route involves multiple protein components that allow the flux of S to be precisely regulated as a function of environmental cues to avoid the unnecessary accumulation of toxic concentrations of soluble sulfide (S2-). The first enzyme in this relay system is cysteine desulfurase (CSD). CSD catalyzes the release of sulfane S from L-cysteine by converting it to L-alanine by forming an enzyme-linked persulfide intermediate on its conserved cysteine residue. The persulfide S is then transferred to diverse acceptor proteins for its incorporation into the thio-cofactors. The thio-cofactor binding-proteins participate in essential and diverse cellular processes, including DNA repair, respiration, intermediary metabolism, gene regulation, and redox sensing. Additionally, CSD modulates pathogenesis, antibiotic susceptibility, metabolism, and survival of several pathogenic microbes within their hosts. In this review, we aim to comprehensively illustrate the impact of CSD on bacterial core metabolic processes and its requirement to combat redox stresses and antibiotics. Targeting CSD in human pathogens can be a potential therapy for better treatment outcomes.