title: Coiled-coils in type III secretion systems: structural flexibility, disorder and biological implications.
abstract: Recent structural studies and analyses of microbial genomes have consolidated the understanding of the structural and functional versatility of coiled-coil domains in proteins from bacterial type III secretion systems (T3SS). Such domains consist of two or more α-helices forming a bundle structure. The occurrence of coiled-coils in T3SS is considerably higher than the average predicted occurrence in prokaryotic proteomes. T3SS proteins comprising coiled-coil domains are frequently characterized by an increased structural flexibility, which may vary from localized structural disorder to the establishment of molten globule-like state. The propensity for coiled-coil formation and structural disorder are frequently essential requirements for various T3SS functions, including the establishment of protein-protein interaction networks and the polymerization of extracellular components of T3SS appendages. Possible correlations between the frequently observed N-terminal structural disorder of effectors and the T3SS secretion signal are discussed. The results for T3SS are also compared with other Gram-negative secretory systems.
authors.affiliation: Institute of Molecular Biology and Biotechnology, Foundation of Research and Technology and Department of Biology, University of Crete, Vasilika Vouton, Heraklion, Crete, Greece.
authors.forename: Anastasia D
authors.initials: AD
authors.lastname: Gazi
authors.forename: Spyridoula N
authors.initials: SN
authors.lastname: Charova
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Panopoulos
authors.forename: Michael
authors.initials: M
authors.lastname: Kokkinidis
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D058947:Bacterial Secretion Systems / Q000502:physiology*; D016680:Genome, Bacterial; D006090:Gram-Negative Bacteria / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D020539:Sequence Analysis, Protein
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems