Exploiting an evolutionary constraint: Targeting TatD nuclease with chrysosplenol D disrupts Mycoplasma gallisepticum infection.

Abstract

Mycoplasma gallisepticum (MG) poses a substantial constraint on global poultry production as a prevalent avian pathogen. Nucleases exhibit critical regulatory functions in metabolic homeostasis and virulence mechanisms of MG. Targeting these enzymatic mediators may represent a novel therapeutic approach to overcome the limitations in current treatment modalities. This study employed TatD nuclease as a model target to evaluate both its pathogenic potential and assess the feasibility of nuclease-targeted therapy against MG infection. The results demonstrated that TatD nuclease was capable of degrading host DNA, RNA, plasmid and neutrophil extracellular traps (NETs), while inducing apoptosis in HD-11 cells. Through integrated computational prediction, site-directed mutagenesis, and bio-layer interferometry (BLI) experiments identified chrysosplenol D (CD) as a potent inhibitor of TatD nuclease. CD exhibited strong binding affinity to TatD nuclease through interactions with the amino acid residues Cys158, His157 and Asp 211. Treatment with CD effectively blocked the nuclease action of TatD and inhibited the colonization of MG in chicks. Furthermore, treatment with CD significantly reduced the effects of Th1/Th2 immune drift, oxidative stress, and enhanced respiratory mucosal barrier function, induced by MG infection. Collectively, our findings demonstrate that nucleases as critical virulence factors in MG, while concurrently may representing evolutionarily conserved vulnerabilities.