An Integrated Quantitative and Targeted Proteomics Reveals Fitness Mechanisms of Aeromonas hydrophila under Oxytetracycline Stress

To
date, above ten thousand tons of antibiotics are used in aquaculture
each year that lead to the deterioration of natural resources. However,
knowledge is limited on the molecular biological behavior of common
aquatic pathogens against antibiotics stress. In this study, proteomics
profiles of Aeromonas hydrophila, which
were exposed to different levels of oxytetracycline (OXY) stress,
were displayed and compared using iTRAQ labeling and SWATH-MS based
LC–MS/MS methods. A total 1383 proteins were identified by
SWATH-MS method, and 2779 proteins were identified from iTRAQ labeling
samples. There are 152 up-regulated and 52 down-regulated proteins
overlapped in 5 μg/mL OXY stress and both 83 up- and down-regulated
proteins overlapped in 10 μg/mL OXY stress in both methods,
respectively. Results show that many protein synthesis and translation
related proteins increased, while energy generation related proteins
decreased in OXY stress. The varieties of selected proteins involved
in both pathways were further validated by sMRMHR, q-PCR,
and enzyme activity assay. Furthermore, the concentrations of NAD+
and NADH were measured to verify the characteristic of energy generation
process in OXY stress and OXY resistance strain. We demonstrate that
the down-regulation of energy generation related metabolic pathways
and up-regulation of translation may play an important role in antibiotics
fitness or resistance of aquatic pathogens.