Flavobacterium johnsoniae GldH Is a Lipoprotein That Is Required for Gliding Motility and Chitin Utilization

Abstract

Cells of Flavobacterium johnsoniae move rapidly over surfaces by gliding motility. The mechanism of this form of motility is not known. Six genes (gldA, gldB, gldD, gldF, gldG, and ftsX) that are required for gliding have been described. Tn4351 mutagenesis was used to identify another gene, gldH, which is required for cell movement. GldH mutants formed nonspreading colonies, and individual cells lacked the cell movements and ability to propel latex spheres along their surfaces that are characteristic of wild-type cells. gldH mutants also failed to digest chitin and were resistant to bacteriophages that infect wild-type cells. Introduction of pMM293, which carries wild-type gldH, restored to the gldH mutants colony spreading, cell motility, the ability to move latex spheres, phage sensitivity, and the ability to digest chitin. gldH encodes a predicted 141-amino-acid protein that localized to the membrane fraction. Labeling studies with [ 3 H]palmitate demonstrated that GldH is a lipoprotein. GldB and GldD, which were previously described, also appear to be lipoproteins. GldH does not exhibit significant amino acid similarity to proteins of known function in the databases. Putative homologs of gldH of unknown function are found in motile (Cytophaga hutchinsonii) and apparently nonmotile (Bacteroides thetaiotaomicron, Bacteroides fragilis, Tannerella forsythensis, Porphyromonas gingivalis, and Prevotella intermedia) members of the Cytophaga-Flavobacterium-Bacteroides group.

Flavobacterium johnsoniaeGliding Motility Genes Identified bymarinerMutagenesis

“…Wild-type cells of F. johnsoniae digest chitin (43) whereas many nonmotile mutants fail to utilize this insoluble polysaccharide (5,7,27,28). The effects of mutations in gldK, gldL, gldM, and gldN on chitin utilization were determined in PY2 medium supplemented with chitin.…”

“…gldA, gldF, and gldG are thought to encode components of an ATPbinding cassette (ABC) transporter that is required for motility (1,15). Genes encoding lipoproteins that are required for gliding (GldB, GldD, GldH, GldI, and GldJ) have also been identified (5,16,17,27,28). Cells with mutations in any of these genes are completely nonmotile.…”

“…To observe colony spreading, F. johnsoniae was grown on PY2 agar medium (1) at 25°C. Chitin utilization was detected as previously described except that strains derived from F. johnsoniae FJ1 were incubated for 3 days whereas strains derived from F. johnsoniae MM101 were incubated for 12 days because of the partial deficiency in chitin utilization (27,28). Antibiotics were used at the indicated concentrations when needed: ampicillin, 100 g/ml; cefoxitin, 100 g/ml; chloramphenicol, 30 g/ml; erythromycin, 100 g/ml; kanamycin, 30 g/ml; tetracycline, 20 g/ml.…”

Susceptibility of zebra fish Danio rerio to infection by Flavobacterium columnare and F. johnsoniae

“…It is also the only Flavobacterium for which a robust genetics system exists (McBride 2004). Gliding motility may be linked to F. johnsoniae's ability to digest large polymers (McBride et al 2003). Gliding motility is also a common characteristic of 4 flavobacterial fish pathogens, F. johnsoniae, F. columnare, F. psychrophilum, and F. branchiophilum (Bader & Starliper 2002).…”

Construction of two selectable markers for integrative/conjugative plasmids in Flavobacterium columnare

“…Gliding mechanisms have been elucidated in F. johnsoniae by transposon Tn4351-mediated mutagenesis (Agarwal et al, 1997;Kempf and McBride, 2000;McBride et al, 2003;. In addition, an attenuated strain of F. psychrophilum was produced by Tn4351 mutagenesis that may be useful in vaccination (Alvarez et al, 2008).…”