Table 1.

Composition and functions of H. pylori flagellar structures

Structure	Composition	Function	References
Flagellar basal body	C ring (FliM, FliN, FliY, FliG)	Transfers proteins, regulates motor rotation and conversion, and coordinates protein secretion	[9, 46, 82]
	MS ring (FliF)	Involved in the synthesis of FlaA, FlaB, and FlgE	[3]
	Type III secretion system (FlhA, FliO, FlhB, FliP, FliQ, FliR)	Transports the majority of the flagellar proteins to the end of the flagellar structure	[31, 38, 77]
	Motor (MotA, MotB)	Fixes and rotates the flagellum	[16, 59]
Flagellar hook	Flagellum export chaperone (FliS)	Prevents premature polymerization of flagellin, and participates in flagellum assembly	[3, 41]
	Flagellar hook protein (FlgE)	Connects the basal body and the flagellar filament, and is closely related to the powerful driving force in a viscous environment	[14, 61, 71]
	FlgK	Controls the length of the flagellar hook during flagellum assembly	[14]
Flagellar filament	FlaA, FlaB	Plays an important role in bacterial motility	[3, 32]
	FliD	As a filament-capping protein in flagellar assembly	[36, 37]
Flagellar sheath	HpaA, FaaA	Protect against depolymerization of the flagellin subunits at low pH	[10, 21, 68]