Outer membrane-dependent transport systems in Escherichia coli: turnover of TonB function.
AUTOR(ES)
Kadner, R J
RESUMO
Recent reports demonstrated that the energy-dependent step of vitamin B12 uptake into cells of Escherichia coli rapidly declines after cessation either of the expression of the tonB gene or of general protein synthesis. It is shown here that inhibition of protein synthesis results in the decline, with similar kinetics, of all tonB-dependent processes, including sensitivity to colicins B and Ia, irreversible adsorption of phage phi80, and siderophore-mediated iron uptake. The role of ongoing TonB-dependent reactions on this lability of TonB function was investigated. Ferrichrome and the enterochelin precursor, 2,3-dihydroxybenzoate, caused both a moderate depression of B12 uptake activity in growing cells (reversed upon removal of the siderophore) and an acceleration of the loss of activity following inhibition of protein synthesis by addition of spectinomycin. Strains lacking the tonB-dependent siderophore uptake systems did not show these responses. The results suggest the consumption of tonB product during its action.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=222351Documentos Relacionados
- Outer Membrane-Dependent Transport Systems in Escherichia coli: Effect of Repression or Cessation of Colicin Receptor Synthesis on Colicin Receptor Activities
- Involvement of ExbB and TonB in transport across the outer membrane of Escherichia coli: phenotypic complementation of exb mutants by overexpressed tonB and physical stabilization of TonB by ExbB.
- TonB-Dependent Systems of Uropathogenic Escherichia coli: Aerobactin and Heme Transport and TonB Are Required for Virulence in the Mouse
- Genetic suppression demonstrates interaction of TonB protein with outer membrane transport proteins in Escherichia coli.
- TonB Interacts with Nonreceptor Proteins in the Outer Membrane of Escherichia coli