Antimicrob Agents Chemother 1992,36(4):826–829.PubMed 44. Clements JM, Coignard F, Johnson I, Chandler S, Palan S, Waller A, Wijkmans J, Hunter MG: Antibacterial activities and characterization of novel inhibitors of LpxC. Antimicrob Agents Chemother 2002,46(6):1793–1799.CrossRefPubMed 45. Reuter G, Janvilisri LDE225 T, Venter H, Shahi S, Balakrishnan L, van Veen HW: The ATP binding cassette multidrug transporter LmrA and lipid transporter MsbA have overlapping substrate specificities. J Biol Chem 2003,278(37):35193–35198.CrossRefPubMed 46. Ghanei H, Abeyrathne PD, Lam JS: Biochemical characterization of MsbA from Pseudomonas

aeruginosa. J Biol Chem 2007,282(37):26939–26947.CrossRefPubMed 47. Waidner B, Greiner S, Odenbreit S, Kavermann H, Velayudhan J, Stahler F, Guhl J, Bisse E, van Vliet AH, Andrews SC, et al.: Essential role of ferritin Pfr in Helicobacter pylori iron metabolism and gastric colonization. Infect Immun 2002,70(7):3923–3929.CrossRefPubMed 48. Bleumink-Pluym NM, Verschoor F, Gaastra W, Zeijst BA, Fry BN: A novel approach for the construction of a Campylobacter mutant library. Microbiology 1999,145(Pt 8):2145–2151.CrossRefPubMed 49. Kim JS, Chang

JH, Chung SI, Yum JS: Molecular cloning and characterization of the Helicobacter pylori fliD gene, an essential factor in flagellar structure and motility. J Bacteriol 1999,181(22):6969–6976.PubMed 50. Ryan KA, Karim N, Worku M, Penn CW, O’Toole PW: Helicobacter pylori flagellar hook-filament transition is controlled by a FliK

functional homolog encoded by the gene HP0906. J Bacteriol 2005,187(16):5742–5750.CrossRefPubMed 51. Pflock M, Bathon M, Schar J, Muller PS-341 mouse S, Mollenkopf H, Meyer TF, Beier D: The orphan response regulator HP1021 of Helicobacter pylori regulates transcription of a gene cluster presumably involved in acetone metabolism. J Bacteriol 2007,189(6):2339–2349.CrossRefPubMed 52. Hughes NJ, Clayton CL, Chalk PA, Kelly DJ: Helicobacter pylori porCDAB and oorDABC genes encode distinct pyruvate:flavodoxin and 2-oxoglutarate:acceptor oxidoreductases which mediate electron transport to NADP. J Bacteriol 1998,180(5):1119–1128.PubMed Authors’ contributions HC, TL, and JW conceived and designed the experiments. HC carried out the experiments, analyzed the data, and drafted the manuscript. PRKD3 JY provided clinical isolate strains. TL and JW modified the manuscript. All the authors have read and approved the final manuscript.”
“Background Genome sequencing of diverse bacterial species has revealed widespread distribution of conserved gene products with as-yet unknown functions. Among these are a family of small proteins with approximate molecular masses of 12 kDa, which have been variously classed as “”domain of unknown function”" (DUF) 149, Pfam 2575 and COG-0718 [1]. Such genes have been identified in a wide variety of bacterial phyla, a list that includes many significant pathogens of humans, domestic animals and plants (Fig. 1).