TY - JOUR
T1 - Flagellar assembly in Caulobacter crescentus
T2 - A basal body P-ring null mutation affects stability of the L-ring protein
AU - Mohr, Christian D.
AU - Jenal, Urs
AU - Shapiro, Lucy
PY - 1996/2
Y1 - 1996/2
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0030024154&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0030024154&partnerID=8YFLogxK
U2 - 10.1128/jb.178.3.675-682.1996
DO - 10.1128/jb.178.3.675-682.1996
M3 - Article
C2 - 8550499
AN - SCOPUS:0030024154
SN - 0021-9193
VL - 178
SP - 675
EP - 682
JO - Journal of bacteriology
JF - Journal of bacteriology
IS - 3
ER -