title: The O-Antigen Flippase Wzk Can Substitute for MurJ in Peptidoglycan Synthesis in Helicobacter pylori and Escherichia coli.
abstract: The peptidoglycan (PG) cell wall is an essential component of the cell envelope of most bacteria. Biogenesis of PG involves a lipid-linked disaccharide-pentapeptide intermediate called lipid II, which must be translocated across the cytoplasmic membrane after it is synthesized in the inner leaflet of this bilayer. Accordingly, it has been demonstrated that MurJ, the proposed lipid II flippase in Escherichia coli, is required for PG biogenesis, and thereby viability. In contrast, MurJ is not essential in Bacillus subtilis because this bacterium produces AmJ, an unrelated protein that is functionally redundant with MurJ. In this study, we investigated why MurJ is not essential in the prominent gastric pathogen, Helicobacter pylori. We found that in this bacterium, Wzk, the ABC (ATP-binding cassette) transporter that flips the lipid-linked O- or Lewis- antigen precursors across the inner membrane, is redundant with MurJ for cell viability. Heterologous expression of wzk in E. coli also suppresses the lethality caused by the loss of murJ. Furthermore, we show that this cross-species complementation is abolished when Wzk is inactivated by mutations that target a domain predicted to be required for ATPase activity. Our results suggest that Wzk can flip lipid II, implying that Wzk is the flippase with the most relaxed specificity for lipid-linked saccharides ever identified.
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton T6G 2E9, Alberta, Canada.
authors.forename: Wael
authors.initials: W
authors.lastname: Elhenawy
authors.affiliation: Department of Microbiology, The Ohio State University, Columbus, OH 43210, United States of America.
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Davis
authors.affiliation: Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, United States of America.
authors.forename: Jutta
authors.initials: J
authors.lastname: Fero
authors.affiliation: Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, United States of America.
authors.forename: Nina R
authors.initials: NR
authors.lastname: Salama
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton T6G 2E9, Alberta, Canada.|Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, United States of America.
authors.forename: Mario F
authors.initials: MF
authors.lastname: Felman
authors.affiliation: Department of Microbiology, The Ohio State University, Columbus, OH 43210, United States of America.
authors.forename: Natividad
authors.identifier: http://orcid.org/0000-0002-6369-2206
authors.initials: N
authors.lastname: Ruiz
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D000942:Antigens, Bacterial / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism; D006031:Glycosylation; D016480:Helicobacter pylori / Q000254:growth & development / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism; D010457:Peptidoglycan / Q000096:biosynthesis*; D049294:Phospholipid Transfer Proteins / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D000942:Antigens, Bacterial; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; C584574:MurJ protein, E coli; D010457:Peptidoglycan; D049294:Phospholipid Transfer Proteins; C543926:Wzx protein, E coli