PstSCAB and SapBCDF are putrescine exporters in <i>Proteus mirabilis</i>

Antibiotics are the primary treatment for bacterial urinary tract infections (UTIs). However, overuse of antibiotics promotes the emergence of antibiotic-resistant bacteria; therefore, it is desirable to develop drugs that specifically inhibit virulence without promoting the emergence of antibiotic resistance. <i>Proteus mirabilis</i> causes UTI and uniquely uses putrescine for cell-cell communication during urinary tract invasion. Inhibition of putrescine-mediated cell-cell communication in <i>P. mirabilis</i> impairs its invasion of urothelial cells. Therefore, proteins responsible for putrescine-mediated cell-cell communication are a potential target for treating <i>P. mirabilis</i> UTIs. However, the putrescine exporter of <i>P. mirabilis</i> has yet to be identified. Here, we identified two putrescine exporters of <i>P. mirabilis</i>, PstSCAB and SapBCDF. Furthermore, <i>P. mirabilis</i> ΔpstSCAB and ΔsapBCDF strains showed a lack of swarming activity. This study indicates PstSCAB and SapBCDF as potential targets for treating UTIs caused by <i>P. mirabilis.</i>