The tolZ gene of Escherichia coli is identified as the ftsH gene.
Escherichia coli tolZ mutants are tolerant to colicins E2, E3, D, Ia, and Ib (Tol-), can grow on glucose but not on succinate or other nonfermentable carbon sources (Nfc-), and show temperature-sensitive growth (Ts). A 1.8-kb DNA fragment that complemented the tolZ mutation was cloned. The DNA fragment was sequenced, and one open reading frame was found. This frame was identical to a part of the E. coli FtsH protein, an ATP-dependent metalloprotease that binds to the cytoplasmic membrane. The tolZ gene was located at 69 min on the E. coli genetic map, and the mutation was complemented by a plasmid carrying the ftsH gene, indicating that the tolZ gene is identical to the ftsH gene. The mutated tolZ21 gene was also cloned and sequenced and was found to have a single base change that caused an amino acid alteration of His-418 to Tyr in the FtsH protein. The tolZ21 mutant showed Hfl- (high frequency of lysogenization) and Std- (stop transfer-defective) pheno-types, both of which are due to a mutation in the ftsH (hflB) gene. However, the ftsH1, ftsH101, and hflB29 mutants did not show Tol- and Nfc phenotypes. The tolZ21 mutant was found to have a suppressor mutation, named sfhC, which allowed cells to survive. The sfhC mutation alone caused no Tol-, Nfc-, Ts, or Hfl- phenotypes in the tolZ21 mutant.
Qu
J N
JN
Department of Biotechnology, University of Tokyo, Japan.
Makino
S I
SI
Adachi
H
H
Koyama
Y
Y
Akiyama
Y
Y
Ito
K
K
Tomoyasu
T
T
Ogura
T
T
Matsuzawa
H
H
D049069:ATP-Dependent Proteases; D001426:Bacterial Proteins / Q000235:genetics*; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003087:Colicins / Q000633:toxicity; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D008565:Membrane Proteins / Q000235:genetics*
D001426:Bacterial Proteins; D003087:Colicins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D049069:ATP-Dependent Proteases; C513383:FtsH protein, E coli