title: A two-component regulatory system modulates twitching motility in Dichelobacter nodosus.
abstract: Dichelobacter nodosus is the essential causative agent of footrot in sheep and type IV fimbriae-mediated twitching motility has been shown to be essential for virulence. We have identified a two-component signal transduction system (TwmSR) that shows similarity to chemosensory systems from other bacteria. Insertional inactivation of the gene encoding the response regulator, TwmR, led to a twitching motility defect, with the mutant having a reduced rate of twitching motility when compared to the wild-type and a mutant complemented with the wild-type twmR gene. The reduced rate of twitching motility was not a consequence of a reduced growth rate or decreased production of surface located fimbriae, but video microscopy indicated that it appeared to result from an overall loss of twitching directionality. These results suggest that a chemotactic response to environmental factors may play an important role in the D. nodosus-mediated disease process.
authors.affiliation: Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Monash University, Clayton, Victoria 3800, Australia; Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia.
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Kennan
authors.affiliation: Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Monash University, Clayton, Victoria 3800, Australia; Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia.
authors.forename: Carrie J
authors.initials: CJ
authors.lastname: Lovitt
authors.affiliation: Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Monash University, Clayton, Victoria 3800, Australia; Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Han
authors.affiliation: Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Monash University, Clayton, Victoria 3800, Australia; Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia.
authors.forename: Dane
authors.initials: D
authors.lastname: Parker
authors.affiliation: Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia.
authors.forename: Lynne
authors.initials: L
authors.lastname: Turnbull
authors.affiliation: Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia.
authors.forename: Cynthia B
authors.initials: CB
authors.lastname: Whitchurch
authors.affiliation: Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Monash University, Clayton, Victoria 3800, Australia; Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia. Electronic address: julian.rood@monash.edu.
authors.forename: Julian I
authors.initials: JI
authors.lastname: Rood
mesh_terms: D000818:Animals; D002633:Chemotaxis; D020376:Dichelobacter nodosus / Q000235:genetics* / Q000502:physiology; D010861:Fimbriae, Bacterial / Q000235:genetics* / Q000378:metabolism; D005535:Foot Rot / Q000382:microbiology*; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology / Q000662:veterinary*; D016254:Mutagenesis, Insertional; D012756:Sheep; D012757:Sheep Diseases / Q000382:microbiology*; D015398:Signal Transduction; D014774:Virulence
keywords: Chemotaxis; Dichelobacter nodosus; Footrot; Twitching motility; Type IV fimbriae