Flagellar assembly in Caulobacter crescentus: a basal body P-ring null mutation affects stability of the L-ring protein.
AUTOR(ES)
Mohr, C D
RESUMO
The P- and L-rings are structural components of the flagellar basal body that are positioned in the periplasmic space and outer membrane, respectively. In order to explore the mechanism of P- and L-ring assembly, we examined the effect of a null mutation in the gene encoding the P-ring subunit, FlgI, on the expression, stability, and subcellular localization of the L-ring subunit, FlgH, in Caulobacter crescentus. Transcription of the L-ring gene and synthesis of the L-ring protein were both increased in the P-ring null mutant. However, steady-state L-ring protein levels were dramatically reduced compared with those of wild type. This reduction, which was not observed in flagellar hook mutants, was due to a decreased stability of the L-ring protein. The instability of the L-ring protein was apparent throughout the cell cycle of the P-ring mutant and contrasted with the fairly constant level of L-ring protein during the cell cycle of wild-type cells. Low levels of the L-ring protein were detected exclusively in the cell envelope of cells lacking the P-ring, suggesting that, in the absence of P-ring assembly, L-ring monomers are unable to form multimeric rings and are thus subject to proteolysis in the periplasm.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=177711Documentos Relacionados
- The flk gene of Salmonella typhimurium couples flagellar P- and L-ring assembly to flagellar morphogenesis.
- Organization and temporal expression of a flagellar basal body gene in Caulobacter crescentus.
- Flagellar hook and basal complex of Caulobacter crescentus.
- L-, P-, and M-ring proteins of the flagellar basal body of Salmonella typhimurium: gene sequences and deduced protein sequences.
- A mutation that uncouples flagellum assembly from transcription alters the temporal pattern of flagellar gene expression in Caulobacter crescentus.