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

Abstract

Cells of Flavobacterium johnsoniae glide rapidly over surfaces by an unknown mechanism. Seven genes ( gldA , gldB , gldD , gldF , gldG , gldH , and ftsX ) that are required for gliding motility have been described. Complementation of the nonmotile mutants UW102-41, UW102-85, and UW102-92 identified another gene, gldI , that is required for gliding motility. gldI mutants formed nonspreading colonies, and individual cells were completely nonmotile. They were also resistant to bacteriophages that infect wild-type cells, and they failed to digest chitin. Introduction of wild-type gldI on a plasmid restored colony spreading, cell motility, phage sensitivity, and the ability to digest chitin to the gldI mutants. gldI encodes a predicted 199-amino-acid protein that localized to the membrane fraction. Labeling studies with [ ³ H]palmitate indicated that GldI is a lipoprotein. GldI is similar to peptidyl-prolyl cis/trans -isomerases of the FK506-binding protein family and may be involved in folding cell envelope protein components of the motility machinery.