Quantitative Proteomics Investigating the Molecular Responses of Aeromonas hydrophila to Zinc Stress

The
aquaculture industry has recently reported the emergence of
antibiotic and multimetal-resistant Aeromonas hydrophila strains. However, the intrinsic adaptation mechanisms of A. hydrophila under Zn2+ stress remain
poorly understood. In this study, we employed a data-independent acquisition
(DIA)-based quantitative proteomics approach to investigate global
protein expression changes in A. hydrophila exposed to Zn2+ stress. A total of 338 proteins were
upregulated and 388 were downregulated in response to Zn2+ exposure. Bioinformatic analyses revealed that some of the differentially
expressed proteins (DEPs) were enriched in several Gene Ontology (GO)
terms and KEGG pathways, such as metabolic processes (nucleotide metabolism,
ribonucleotide biosynthesis, purine nucleotide metabolism), membrane-associated
processes (ABC transporter complex), and signaling and energy pathways
(quorum sensing, ABC transporters, and oxidative phosphorylation).
Seven genes encoding protein secretion- and signaling-related proteins
were selected for RT–qPCR analysis to examine whether their
transcriptional responses corresponded to the proteomic trends, providing
complementary insight rather than direct validation of the proteomic
data. Furthermore, we assessed the tolerance of five gene-deletion
mutants to Zn2+ stress. Among them, the ΔAHA_2968 mutant, lacking a GGDEF-domain protein, displayed
pronounced sensitivity to ZnSO4, implicating c-di-GMP signaling
in zinc stress resistance. These findings have shed light on the intrinsic
adaptive mechanisms of A. hydrophila, indicating that they play an important role in resistance to Zn2+.