![]() These findings show that the flagellar secretion apparatus functions as a proton-driven protein exporter and that ATP hydrolysis is not essential for type III secretion. But these proteins showed no significant sequence similarity to any proteins in the protein databases available at the time, including bacterial flagellins. Weak swarming motility and rare flagella were observed in a mutant deleted for FliI and for the non-flagellar type-III secretion ATPases InvJ and SsaN. The export of several flagellar export substrates was prevented by treatment with the protonophore CCCP, with no accompanying decrease in cellular ATP levels. Here we show that flagellar secretion in Salmonella enterica requires the proton motive force (PMF) and does not require ATP hydrolysis by FliI. ATP hydrolysis by the cytoplasmic ATPase complex converts the export gate complex into a. The flagellar secretion apparatus comprises a membrane-embedded complex of about five proteins, and soluble factors, which include export-dedicated chaperones and an ATPase, FliI, that was thought to provide the energy for export. The transmembrane export gate complex is fueled by proton motive force across the cytoplasmic membrane and is divided into four distinct functional parts: a dual-fuel export engine a polypeptide channel a membrane voltage sensor and a docking platform. The tail is a flat ribbon-like (nonmagnetic) metal. The head is magnetic and is made from thin metal layers of chromium, nickel, and gold. They are actually metallic and consist of two parts: a square, flat head and a helical tail. This apparatus is related to the injectisome used by many gram-negative pathogens and symbionts to transfer effector proteins into host cells in both systems this export mechanism is termed 'type III' secretion. Artificial bacterial flagella are nonbiological structures whose design is based on that of bacterial flagella. Bacterial flagella contain a specialized secretion apparatus that functions to deliver the protein subunits that form the filament and other structures to outside the membrane. ![]()
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