Enhanced export of beta-galactosidase fusion proteins in prlF mutants is Lon dependent
| Autor: | Thomas J. Silhavy, W. B. Snyder |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
Protease La
Recombinant Fusion Proteins Two-hybrid screening Mutant Porins lac operon Biology Microbiology Gene product ATP-Dependent Proteases Bacterial Proteins Heat shock protein Escherichia coli Genes Suppressor Lysogeny Molecular Biology Heat-Shock Proteins Escherichia coli Proteins Serine Endopeptidases Biological Transport beta-Galactosidase Fusion protein Molecular biology Cell Compartmentation Membrane protein Chaperone (protein) biology.protein Receptors Virus bacteria Research Article Bacterial Outer Membrane Proteins |
| Zdroj: | Journal of Bacteriology. 174:5661-5668 |
| ISSN: | 1098-5530 0021-9193 |
| DOI: | 10.1128/jb.174.17.5661-5668.1992 |
| Popis: | We have used fusions of the outer membrane protein LamB to beta-galactosidase (encoded by lacZ) to study the protein export process. This LamB-LacZ hybrid protein blocks export when synthesized at high levels, as evidenced by inducer (maltose) sensitivity, a phenomenon termed LacZ hybrid jamming. The prlF1 mutation relieves LacZ hybrid jamming and allows localization of the fusion protein to a noncytoplasmic compartment. prlF1 and similar alleles are gain-of-function mutations. Null mutations in this gene confer no obvious phenotypes. Extragenic suppressors of a gain-of-function prlF allele have been isolated in order to understand how this gene product affects the export process. The suppressors are all lon null mutations, and they are epistatic to all prlF phenotypes tested. Lon protease activity has been measured in prlF1 cells and shown to be increased. However, the synthesis of Lon is not increased in a prlF1 background, suggesting a previously unidentified mechanism of Lon activation. Further analysis reveals that prlF1 activates degradation of cytoplasmically localized precursors in a Lon protease-dependent manner. It is proposed that accumulation of precursors during conditions of hybrid protein jamming titrates an essential export component(s), possibly a chaperone. Increased Lon-dependent precursor degradation would free this component, thus allowing increased protein export under jamming conditions. |
| Databáze: | OpenAIRE |
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