Downregulation of Na(+)-NQR complex is essential for Vibrio alginolyticus in resistance to balofloxacin

► Balofloxacin-resistant V. alginolyticus was analyzed by native/SDS-PAGE proteomics. ► Alteration of NqrA and NqrF from Na(+)-NQR was detected. ► Western blotting confirmed downregulation of NqrA, NqrF. ► Overexpression of NqrA and NqrF validated the role of the two proteins. ► Downregulation of NQR complex is crucial for balofloxacin resistance in this bacterium.