First Lysine Lactylation Profiling in Vibrio alginolyticus and Initial Characterization of VaCobQ as a Candidate...

Vibrio alginolyticus is a common pathogenic bacterium and can cause diseases in aquaculture animals. Lysine lactylation (Kla) is a novel post-translational modification (PTM) that has been confirmed to play critical roles in key biological processes. However, the modification landscape and functions of Kla in V. alginolyticus remain unclear. In this study, lactylation modification profiles of the bacterial pathogen V. alginolyticus were first systematically characterized; a total of 9308 lactylation sites on 2155 proteins were successfully identified. The lactylation of cAMP receptor protein (CRP) and triosephosphate isomerase (TPI) was verified by Co-immunoprecipitation (Co-IP) and Western blot to validate the lactylome data. Bioinformatic analysis of the Kla sites revealed 32 conserved sequence motifs surrounding the modified residues. Kla proteins were mainly involved in central metabolic pathways, including glycolysis/gluconeogenesis and ribosome biogen regulators were found to contain Kla modification sites. To investigate crosstalk among lysine acylations in V. alginolyticus, we integrated Kla, lysine acetylation (Kac), and lysine succinylation (Ksuc) profiles and identified 337 co-modified proteins and 5 co-modified sites. Additionally, phylogenetic analysis of Vibrio alginolyticus CobQ based on protein sequence alignment revealed no homology to the known delactylase CobB. Combined in vitro and in vivo functional validation identified VaCobQ as a candidate delactylase with potential NAD⁺-independent activity. This study establishes a lysine lactylation landscape in V. alginolyticus, providing a resource for exploring Kla functions in bacterial metabolism and its possible connections to virulence.