title: Genetic analysis of revertants isolated from the rod-fragilefliFmutant ofSalmonella.
abstract: FliF is the protein comprising the MS-ring of the bacterial flagellar basal body, which is the base for the assembly of flagellar axial structures. From afliFmutant that easily releases the rod-hook-filament in viscous environments, more than 400 revertants that recovered their swarming ability in viscous conditions, were isolated. The second-site mutations were determined for approximately 70% of them. There were three regions where the mutations were localized: two in Region I, 112 in Region II, and 71 in Region III including the true reversion. In Region I, second-site mutations were found in FlgC and FlgF of the proximal rod, suggesting that they affect the interaction between the MS-ring and the rod. In Region II, there were 69 and 42 mutations in MotA and MotB, respectively, suggesting that the second-site mutations in MotA and MotB may decrease the rotational speed of the flagellar motor to reduce the probability of releasing the rod under this condition. One exception is a mutation in FlhC that caused a down regulation of the flagellar proteins production but it may directly affect transcription or translation ofmotAandmotB. In Region III, there were 44, 24, and 3 mutations in FliG, FliM, and FliF, respectively. There were no second-site mutations identified in FliN although it is involved in torque generation as a component of the C-ring. Many of the mutations were involved in the motor rotation, and it is suggested that such reduced speeds result in stabilizing the filament attachment to the motor.
authors.affiliation: Protonic NanoMachine Project, ERATO, JST, Seika, Kyoto 619-0237, Japan.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Komatsu
authors.affiliation: Division of Molecular Science, Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Hayashi
authors.affiliation: Department of Biosciences, Teikyo University, Utsunomiya, Tochigi 320-8551, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Sasa
authors.affiliation: Department of Biosciences, Teikyo University, Utsunomiya, Tochigi 320-8551, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Shikata
authors.affiliation: Izumi Campus, Meiji University, Suginamiku, Tokyo 168-8555, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Yamaguchi
authors.affiliation: Protonic NanoMachine Project, ERATO, JST, Seika, Kyoto 619-0237, Japan; Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Namba
authors.affiliation: Protonic NanoMachine Project, ERATO, JST, Seika, Kyoto 619-0237, Japan; Division of Molecular Science, Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan; Department of Biosciences, Teikyo University, Utsunomiya, Tochigi 320-8551, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Oosawa
keywords: MS-ring; bacterial flagellum; motor; revertant; rod