Roles of Lipopolysaccharide Glycosyltransferases in Maintenance ofHelicobacter pyloriMorphology, Cell Wall Permeability, and Antimicrobial Susceptibilities

Abstract

AbstractHelicobacter pyloriunique lipopolysaccharide structure is essential in maintaining the cell envelop integrity and renders the bacterium natural resistance to cationic antimicrobial peptides (CAMPs). Our group has recently elucidated the complete set of LPS glycosyltransferase genes inH. pylorireference strain G27. Here, with a series of 8 systematically constructed LPS glycosyltransferase gene mutants (G27ΔHP1578, G27ΔHP1283, G27ΔHP0159, G27ΔHP0479, G27ΔHP0102, G27ΔwecA, G27ΔHP1284and G27ΔHP1191), we investigated the roles ofH. pyloriLPS glycosyltransferases in maintenance of cell morphology, cell wall permeability, and antimicrobial susceptibilities. We demonstrated that deletion of these LPS glycosyltransferase genes did not interfere with bacterial cell wall permeability, but resulted in significant morphological changes (coccoid, coiled “c”-shape, and irregular shapes) after 48 h growth as compared to the rod-like cell shape of the wild-type strain. Moreover, as compared with the wild-type, none of the LPS mutants had altered susceptibility against clarithromycin, levofloxacin, amoxicillin, tetracycline, and metronidazole. However, the deletion of the conserved LPS glycosyltransferases, especially the O-antigen initiating enzyme WecA displayed a dramatic increase in susceptibility to the CAMP polymyxin B and rifampicin. Taken together, our findings suggest that the LPS glycosyltransferases play critical roles in the maintenance of the typical spiral morphology ofH. pylori, as well as resistance to CAMPs and rifampicin. The LPS glycosyltransferases could be promising targets for developing novel anti-H. pyloridrugs.ImportanceH. pyloritypical helical morphology, cell wall integrity, as well as resistance to cationic CAMPs and antimicrobials are significant factors for its long-term colonization and persistent infection in human gastric mucosa. Our results show that each of the 8 LPS glycosyltransferase genes (HP1578,HP1283,HP0159,HP0479,HP0102,wecA,HP1284andHP1191) deletion did not interfere with bacterial cell wall permeability, but resulted in significant loss ofH. pyloritypical helical shape. Furthermore, deletion of the conserved LPS glycosyltransferases, especially the O-antigen initiating enzyme WecA displayed a dramatic increase in susceptibility to the CAMP polymyxin B and rifampicin. Taken together, we believe that the LPS glycosyltransferases are good targets for developing novel anti-H. pyloridrugs.