Subunit organization and reversal-associated movements in the flagellar switch of Escherichia coli.
J Biol Chem
; 285(1): 675-84, 2010 Jan 01.
Article
em En
| MEDLINE
| ID: mdl-19858188
ABSTRACT
Bacterial flagella contain a rotor-mounted protein complex termed the switch complex that functions in flagellar assembly, rotation, and clockwise/counterclockwise direction control. In Escherichia coli and Salmonella, the switch complex contains the proteins FliG, FliM, and FliN and corresponds structurally with the C-ring in the flagellar basal body. Certain features of subunit organization in the switch complex have been deduced previously, but details of subunit organization in the lower part of the C-ring and the molecular movements responsible for motor switching remain unclear. In this study, we use cross-linking, binding, and mutational experiments to examine subunit organization in the bottom of the C-ring and to probe movements that occur upon switching. The results show that FliN tetramers alternate with FliM C-terminal domains to form the bottom of the C-ring in an arrangement that closely reproduces the major features observed in electron microscopic reconstructions. When motors were switched to clockwise rotation by a repellent stimulus, cross-link yields were altered in a pattern indicating relative movement of FliN and FliM(C). These results are discussed in the framework of a structurally grounded hypothesis for the switching mechanism.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Subunidades Proteicas
/
Escherichia coli
/
Flagelos
Tipo de estudo:
Risk_factors_studies
Idioma:
En
Ano de publicação:
2010
Tipo de documento:
Article