Song, W. J. | bioRxiv Science

bioRxiv2024

Discovery of Highly Active Kynureninases for Cancer Immunotherapy through Protein Language Model

Overcoming the immunosuppressive tumor microenvironment is a promising strategy in anticancer therapy. L-kynurenine, a strong immunosuppressive metabolite can be degraded through kynureninases. Through homology searches and protein language models, we identified and then experimentally determined the efficacy of four top-ranked kynureninases. The catalytically most active one nearly doubles turnover number over the prior best, reducing tumor weight by 3.42 times in mouse model comparisons, and thus, presenting substantial therapeutic potential.

cancer biology↗

bioRxiv2021

Molecular mechanism underlying substrate recognition of the peptide macrocyclase PsnB

Graspetides, also known as omega-ester-containing peptides (OEPs), are a family of ribosomally synthesized and post-translationally modified peptides (RiPPs) bearing side-to-side macrolactone or macrolactam linkages. Here we present molecular details of the precursor recognition of the macrocyclase enzyme PsnB in the biosynthesis of plesiocin, a Group 2 graspetide. Biochemical analysis revealed that, in contrast to other RiPPs, the core region of the plesiocin precursor peptide noticeably enhanced the enzyme-precursor interaction via the conserved glutamates. We obtained four crystal structures of symmetric or asymmetric PsnB dimers including those with a bound core peptide and a nucleotide, and suggest that the highly conserved Arg213 at the enzyme active site specifically recognizes a ring-forming acidic residue and escorts it to ATP for phosphorylation. Collectively, this study provides insights into the mechanism underlying substrate recognition in the graspetide biosynthesis, and lays a foundation for engineering new variants.

biochemistry↗