Protein flightless-1 (FliI) was first identified in the Drosophila melanogaster []. It belongs to the Villin/Gelsolin family, whose members are actin-modulating proteins that sever F-actin, cap the barbed ends of actin filaments preventing monomer exchange, and promote the nucleation step of actin polymerisation [].This entry represent FliI and its homologues. FliI may serve as a nuclear receptor coactivator []and is involved in embryonic development []. In mouse fibroblasts it caps actin filaments and localises to focal adhesions, which collectively affect focal adhesion maturation [].
This family represent the bacterial flagellum-specific ATP synthase, FliI, which is needed for flagellar assembly. FliI is part of the flagellar type III protein export apparatus acting as an ATPase to drive protein export for flagellar biosynthesis [, , ]. When FliI is not engaged in flagellar protein export, FliH, another flagellar type III protein export apparatus protein, functions as a negative regulator to prevent FliI from hydrolysing ATP []. It has been suggested that the N terminus of FliI interacts with FliH, while the the C-terminal domain of FliI possesses the ATPase catalytic function [, ]. The structure of the N-terminally truncated variant of FliI lacking the first 18 residues have been determinded [].This entry represents one (of three) segment of the FliI family tree.
Members of this protein family are the FliI protein of bacterial flagellum systems. FliI is an ATPase that acts to drive protein export for flagellar biosynthesis []. The most closely related family is the YscN family of bacterial type III secretion systems. This entry represents one (of three) segment of the FliI family tree. These have been modeled separately in order to exclude the type III secretion ATPases more effectively.
Members of this protein family are the FliI protein of bacterial flagellum systems. This protein acts to drive protein export for flagellar biosynthesis []. The most closely related family is the YscN family of bacterial type III secretion systems. This model represents one (of three) segment of the FliI family tree. These have been modeled separately in order to exclude the type III secretion ATPases more effectively.
Many flagellar proteins are exported by a flagellum-specific export pathway. Attempts have been made to characterise the apparatus responsible for this process, by designing assays to screen for mutants with export defects []. Experiments involving filament removal from temperature-sensitive flagellar mutants of Salmonella typhimurium have shown that, while most mutants were able to regrow filaments, flhA, fliH, fliI and fliN mutants showed no or greatly reduced regrowth. This suggests that the corresponding gene products are involved in the process of flagellum-specific export. The sequences of fliH, fliI and the adjacent gene, fliJ, have been deduced. FliJ was shown to encode a protein of molecular mass 17,302 Da []. It is a membrane-associated protein that affects chemotactic events, mutations in FliJ result in failure to respond to chemotactic stimuli.This subgroup is dominated by FliJ proteins found in Proteobacteria.
Proteins in this entry show extensive homology to the ATP synthase F1 beta subunit, and are involved in type III protein secretion. They fall into the two separate functional groups outlined below.The first group, exemplified by the Salmonella typhimurium FliI protein (), is needed for flagellar assembly. Most structural components of the bacterial flagellum are translocated through the central channel of the growing flagellar structure by the type III flagellar protein-export apparatus in an ATPase-driven manner, to be assembled at the growing end. FliI is the ATPase that couples ATP hydrolysis to the translocation reaction [, ].The second group couples ATP hydrolysis to protein translocation in non-flagellar type III secretion systems. Often these systems are involved in virulence and pathogenicity. YscN () from pathogenic Yersinia species, for example, energises the injection of anti host factors directly into eukaryotic cells, thus overcoming host defences [, ].
Many flagellar proteins are exported by a flagellum-specific export pathway. Attempts have been made to characterisethe apparatus responsible for this process, by designing assays to screen for mutants with export defects.Experiments involving filament removal from temperature-sensitive flagellar mutants of Salmonella typhimurium haveshown that, while most mutants were able to regrow filaments, flhA, fliH, fliI and fliN mutants showed no or greatlyreduced regrowth. This suggests that the corresponding gene products are involved in the process of flagellum-specific export []. The sequence of fliH has been deduced and shown to encode a protein of molecular massof 25,782 Da.
Leucine-rich repeat flightless-interacting protein 1 (LRRFIP1) is a transcriptional repressor which preferentially binds to the GC-rich consensus sequence (5'-AGCCCCCGGCG-3') and may regulate expression of TNF, EGFR and PDGFA []. It may control smooth muscle cell proliferation following artery injury through PDGFA repression and may also bind double-stranded RNA. It interacts with the leucine-rich repeat domain of human flightless-I (FliI) protein [].Leucine-rich repeat flightless-interacting protein 2 (LRRFIP2) may function as activator of the canonical Wnt signaling pathway, in association with DVL3, upstream of CTNNB1/beta-catenin []. It positively regulates Toll-like receptor (TLR) signalling in response to agonist probably by competing with the negative FLII regulator for MYD88-binding [].
This entry represents a region found in the flagellar assembly protein FliH, as well as in type III secretion system protein HrpE.Many flagellar proteins are exported by a flagellum-specific export pathway. Attempts have been made to characterise the apparatus responsible for this process, by designing assays to screen for mutants with export defects.Experiments involving filament removal from temperature-sensitive flagellar mutants of Salmonella typhimurium have shown that, while most mutants were able to regrow filaments, flhA, fliH, fliI and fliN mutants showed no or greatly reduced regrowth. This suggests that the corresponding gene products are involved in the process of flagellum-specific export []. The sequence of fliH has been deduced and shown to encode a protein of molecular mass of 25,782 Da.Bacterial HrpE proteins are belived to function on the type III secretion system, specifically the secretion of HrpZ (harpinPss) [].
