Heat-shock proteins can substitute for SecB function during protein export in Escherichia coli.
AUTOR(ES)
Altman, E
RESUMO
In this study we have shown that (i) induction of the heat-shock response can substitute for SecB function in Escherichia coli, (ii) SecB itself is not a heat-shock protein and (iii) a basal level of heat-shock proteins is required for cells to grow in the absence of a functional SecB protein. Overproduction of DnaK, or GroEL/ES, which were candidates for the heat-shock proteins that could substitute for SecB function, did not rescue the export defect caused when SecB was limiting or absent. In an attempt to identify the heat-shock protein(s) which could substitute for SecB function, unlinked suppressors of secB were isolated and characterized. Interestingly, most of the suppressors mapped to the rpoH locus. Since rpoH encodes sigma 32, the heat-shock transcription factor, it is likely that these suppressors affect the synthesis levels of heat-shock proteins that can substitute for SecB function. The remaining suppressors did not map to any known heat-shock or export genes. Collectively, our data suggest that these suppressors may represent unidentified heat-shock proteins or export factors that act in a manner similar to SecB in facilitating the export process in E. coli.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=452639Documentos Relacionados
- Evidence for protection by heat-shock proteins against photoinhibition during heat-shock
- Effects of mutations in heat-shock genes groES and groEL on protein export in Escherichia coli.
- prlA suppression of defective export of maltose-binding protein in secB mutants of Escherichia coli.
- Archaebacterial heat-shock proteins
- Mutations that improve export of maltose-binding protein in SecB- cells of Escherichia coli.
