Wei Cao

Nonribosomal peptide synthetases (NRPS) are essential for the biosynthesis of therapeutically valuable molecules, including antibiotics, immunosuppressants, and anticancer agents. The assembly-line mechanism of NRPS offers significant potential for engineering novel natural products through reprogramming. However, the challenging purification of NRPS proteins has impeded the investigation of their assembly and catalytic mechanisms. In this study, we employed homologous recombination to insert a purification tag at the C-terminus of the NRPS gene within the chromosome. This genetic modification enabled efficient purification of NRPS proteins from the tagged mutant strain using a one-step affinity chromatography approach. Additionally, we discovered that MbtH-like proteins (MLPs) form stable complexes with all pyoverdine (PVD) NRPS subunits, allowing for the purification of the entire NRPS assembly line via tagged MLP. Negative stain electron microscopy analysis revealed that the purified PVD NRPS proteins exist as dynamically linear monomers. Our in-situ tag-based purification method enhances NRPS research in both biochemical and structural biology, providing a robust platform for further investigations into NRPS mechanisms and applications.

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by polyarticular, symmetric, and aggressive inflammation of the small joints in the hands and feet, resulting in dysfunction. With progress and development in medicine, treatment of RA is constantly evolving, making several drugs available for the treatment of RA. From the nonsteroidal anti-inflammatory drugs (NSAIDs) at the start of illness to glucocorticoids and then to conventional synthetic DMARDs (csDMARDs), biologic DMARDs (bDMARDs), and targeted synthetic DMARDs (tsDMARDs), therapeutic-use drugs for RA have been keeping pace with scientific research. However, various types of drugs have additional side effects when used over the long-term. New and emerging biological and targeted agents have been widely applied in recent years; however, the side effects have not been thoroughly investigated. In this paper, we review the research progress on liver damage caused by novel biological and targeted agents available for RA treatment. The aim is to provide a reference for rational clinical administration of such drugs.