title: Initial characterization of the FlgE hook high molecular weight complex of Borrelia burgdorferi.
abstract: The spirochete periplasmic flagellum has many unique attributes. One unusual characteristic is the flagellar hook. This structure serves as a universal joint coupling rotation of the membrane-bound motor to the flagellar filament. The hook is comprised of about 120 FlgE monomers, and in most bacteria these structures readily dissociate to monomers (∼ 50 kDa) when treated with heat and detergent. However, in spirochetes the FlgE monomers form a large mass of over 250 kDa [referred to as a high molecular weight complex (HMWC)] that is stable to these and other denaturing conditions. In this communication, we examined specific aspects with respect to the formation and structure of this complex. We found that the Lyme disease spirochete Borrelia burgdorferi synthesized the HMWC throughout the in vitro growth cycle, and also in vivo when implanted in dialysis membrane chambers in rats. The HMWC was stable to formic acid, which supports the concept that the stability of the HMWC is dependent on covalent cross-linking of individual FlgE subunits. Mass spectrometry analysis of the HMWC from both wild type periplasmic flagella and polyhooks from a newly constructed ΔfliK mutant indicated that other proteins besides FlgE were not covalently joined to the complex, and that FlgE was the sole component of the complex. In addition, mass spectrometry analysis also indicated that the HMWC was composed of a polymer of the FlgE protein with both the N- and C-terminal regions remaining intact. These initial studies set the stage for a detailed characterization of the HMWC. Covalent cross-linking of FlgE with the accompanying formation of the HMWC we propose strengthens the hook structure for optimal spirochete motility.
authors.affiliation: Department of Microbiology, Immunology, and Cell Biology, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia, United States of America.
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Miller
authors.affiliation: Department of Microbiology and Immunology, East Carolina University, Greenville, North Carolina, United States of America.
authors.forename: Md A
authors.initials: MA
authors.lastname: Motaleb
authors.affiliation: Department of Pathology and Laboratory Medicine, Medical School, University of Texas Health Science Center at Houston, Houston, Texas, United States of America.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Pathology and Laboratory Medicine, Medical School, University of Texas Health Science Center at Houston, Houston, Texas, United States of America.
authors.forename: Bo
authors.initials: B
authors.lastname: Hu
authors.affiliation: Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut, United States of America.
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Caimano
authors.affiliation: Department of Biochemistry, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia, United States of America.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Miller
authors.affiliation: Department of Microbiology, Immunology, and Cell Biology, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia, United States of America.
authors.forename: Nyles W
authors.initials: NW
authors.lastname: Charon
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D025065:Borrelia burgdorferi / Q000235:genetics / Q000378:metabolism*; D005407:Flagella / Q000235:genetics / Q000378:metabolism*; D008193:Lyme Disease / Q000235:genetics / Q000378:metabolism; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D017434:Protein Structure, Tertiary; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D001426:Bacterial Proteins; C097681:FlgE protein, Bacteria; D046912:Multiprotein Complexes