title: Identification of the flagellar chaperone FlgN in the phytopathogen Xanthomonas axonopodis pathovar citri by its interaction with hook-associated FlgK.
abstract: Genome annotation of the plant pathogen Xanthomonas axonopodis pv. citri (Xac), identified flagellar genes in a 15.7 kb gene cluster. However, FlgN, a secretion chaperone for hook-associated proteins FlgK and FlgL, was not identified. We performed extensive screening of the X. axonopodis pv. citri genome with the yeast two-hybrid system to identify a protein with the characteristics of the flagellar chaperone FlgN. We found a candidate (XAC1990) encoded by an operon for components of the flagellum apparatus that interacted with FlgK. In order to further support this finding, Xac FlgK and XAC1990 were cloned, expressed, and purified. The recombinant proteins were characterized by spectroscopic methods and their interaction in vitro confirmed by pull-down assays. We, therefore, conclude that XAC1990 and its homologs in other Xanthomonas species are, in fact, FlgN proteins. These observations extend the sequence diversity covered by this family of proteins.
authors.affiliation: Laboratório Nacional de Luz Síncrotron, CEP 13084-971 Campinas, SP, Brazil.
authors.forename: Letícia
authors.initials: L
authors.lastname: Khater
authors.forename: Marcos C
authors.initials: MC
authors.lastname: Alegria
authors.forename: Paula F L
authors.initials: PF
authors.lastname: Borin
authors.forename: Túlio M
authors.initials: TM
authors.lastname: Santos
authors.forename: Cássia
authors.initials: C
authors.lastname: Docena
authors.forename: Ljubica
authors.initials: L
authors.lastname: Tasic
authors.forename: Chuck S
authors.initials: CS
authors.lastname: Farah
authors.forename: Carlos H I
authors.initials: CH
authors.lastname: Ramos
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D005407:Flagella / Q000502:physiology*; D018832:Molecular Chaperones / Q000378:metabolism; D008969:Molecular Sequence Data; D020798:Two-Hybrid System Techniques; D053532:Xanthomonas axonopodis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; C088595:FlgK protein, Bacteria; C087498:FlgN protein, Bacteria; D018832:Molecular Chaperones