Abstract: Objective To examine the role of Escherichia coli outer membrane protein T in urinary tract infection(UTI).Methods The gene encoding human-beta-defensin-4(HBD-4) was amplifide by PCR and then cloned into vector pET-28a to construct pET-28a/HBD4.The His-HBD4 expression was induced by isopropyl-β-D-thioglactopyranoside(IPTG).The antimicrobial activity of the HBD-4 was tested by minimal inhibitory concentration(MIC) and agarose diffusion method was used to observe the differences in hydrolysis of HBD-4 induced by CFT073 and CFT073△ompT.Results The recombinant expression vetor pET-28a/HBD4 was successfully constructed.There were differences in hydrolysis of HBD-4 induced by wild-type,the complementation and mutant strains.The MIC of HBD-4 for wild-type was 10 μg/ml but that of for mutant strain was 6 μg/ml.After co-incubated with HBD-4,the growth of mutant strain was inhibited but that of the wild-type strain was not affected obviously.Conclusion Escherichia coli outer membrane protein Thydrolyzes HBD-4,which plays an important role in the pathogenesis of uropathogenic Escherichia coli-induced UTI.