title: Inactivation of ferric uptake regulator (Fur) attenuates Helicobacter pylori J99 motility by disturbing the flagellar motor switch and autoinducer-2 production.
abstract: BACKGROUND
  Flagellar motility of Helicobacter pylori has been shown to be important for the bacteria to establish initial colonization. The ferric uptake regulator (Fur) is a global regulator that has been identified in H. pylori which is involved in the processes of iron uptake and establishing colonization. However, the role of Fur in H. pylori motility is still unclear.
  
  
  METHODS
  Motility of the wild-type, fur mutant, and fur revertant J99 were determined by a soft-agar motility assay and direct video observation. The bacterial shape and flagellar structure were evaluated by transmission electron microscopy. Single bacterial motility and flagellar switching were observed by phase-contrast microscopy. Autoinducer-2 (AI-2) production in bacterial culture supernatant was analyzed by a bioluminescence assay.
  
  
  RESULTS
  The fur mutant showed impaired motility in the soft-agar assay compared with the wild-type J99 and fur revertant. The numbers and lengths of flagellar filaments on the fur mutant cells were similar to those of the wild-type and revertant cells. Phenotypic characterization showed similar swimming speed but reduction in switching rate in the fur mutant. The AI-2 production of the fur mutant was dramatically reduced compared with wild-type J99 in log-phase culture medium.
  
  
  CONCLUSIONS
  These results indicate that Fur positively modulates H. pylori J99 motility through interfering with bacterial flagellar switching.
authors.affiliation: Institute of Molecular Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Ai-Yun
authors.initials: AY
authors.lastname: Lee
authors.affiliation: Department of Biotechnology and Laboratory Science in Medicine, School of Biomedical Science and Engineering, National Yang Ming University, Taipei, Taiwan.
authors.forename: Cheng-Yen
authors.initials: CY
authors.lastname: Kao
authors.affiliation: Department of Physics and Graduate Institute of Biophysics, National Central University, Jhongli, Taiwan.
authors.forename: Yao-Kuan
authors.initials: YK
authors.lastname: Wang
authors.affiliation: Department of Physics and Graduate Institute of Biophysics, National Central University, Jhongli, Taiwan.
authors.forename: Ssu-Yuan
authors.initials: SY
authors.lastname: Lin
authors.affiliation: Department of Physics and Graduate Institute of Biophysics, National Central University, Jhongli, Taiwan.
authors.forename: Tze-Ying
authors.initials: TY
authors.lastname: Lai
authors.affiliation: Department of Internal Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.|Department of Internal Medicine, Tainan Hospital, Ministry of Health & Welfare, Taiwan.
authors.forename: Bor-Shyang
authors.identifier: http://orcid.org/0000-0002-1500-6929
authors.initials: BS
authors.lastname: Sheu
authors.affiliation: Department of Physics and Graduate Institute of Biophysics, National Central University, Jhongli, Taiwan.
authors.forename: Chien-Jung
authors.initials: CJ
authors.lastname: Lo
authors.affiliation: Department of Biotechnology and Laboratory Science in Medicine, School of Biomedical Science and Engineering, National Yang Ming University, Taipei, Taiwan.
authors.forename: Jiunn-Jong
authors.identifier: http://orcid.org/0000-0001-8975-8085
authors.initials: JJ
authors.lastname: Wu
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D001431:Bacteriological Techniques; D003470:Culture Media / Q000737:chemistry; D005407:Flagella / Q000235:genetics / Q000502:physiology*; D055786:Gene Knockout Techniques; D016480:Helicobacter pylori / Q000235:genetics / Q000502:physiology*; D006714:Homoserine / Q000031:analogs & derivatives* / Q000378:metabolism; D007783:Lactones / Q000378:metabolism*; D008124:Locomotion; D008163:Luminescent Measurements; D046529:Microscopy, Electron, Transmission; D008858:Microscopy, Phase-Contrast; D018715:Microscopy, Video; D020409:Molecular Motor Proteins / Q000378:metabolism*; D012097:Repressor Proteins / Q000172:deficiency / Q000378:metabolism*; D013489:Suppression, Genetic
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D007783:Lactones; D020409:Molecular Motor Proteins; C091088:N-octanoylhomoserine lactone; D012097:Repressor Proteins; C068477:ferric uptake regulating proteins, bacterial; D006714:Homoserine
keywords: 
  Helicobacter pylori
  ; Fur; autoinducer-2; flagella; motility