Overexpression of Protease-Deficient DegP S210A Rescues the Lethal Phenotype of Escherichia coli OmpF Assembly Mutants in a degP Background
| Autor: | Rajeev Misra, Maria Castillo-Keller, Ming Deng |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
Phenylalanine
medicine.medical_treatment Mutant Gene Expression Porins Mutagenesis (molecular biology technique) Cell Surfaces Biology Microbiology Bacterial Proteins Mutant protein Escherichia coli medicine Inner membrane Thermolabile Molecular Biology Heat-Shock Proteins Protease Serine Endopeptidases Periplasmic space Up-Regulation Kinetics Phenotype Amino Acid Substitution Biochemistry Mutagenesis Periplasmic Proteins Bacterial outer membrane |
| Zdroj: | Journal of Bacteriology. 182:4882-4888 |
| ISSN: | 1098-5530 0021-9193 |
| DOI: | 10.1128/jb.182.17.4882-4888.2000 |
| Popis: | Replacement of OmpF's conserved carboxy-terminal phenylalanine with dissimilar amino acids severely impaired its assembly into stable trimers. In some instances, interactions of mutant proteins with the outer membrane were also affected, as judged by their hypersensitivity phenotype. Synthesis of all mutant OmpF proteins elevated the expression of periplasmic protease DegP, and synthesis of most of them made its presence obligatory for cell viability. These results showed a critical role for DegP in the event of aberrant outer membrane protein assembly. The lethal phenotype of mutant OmpF proteins in a degP null background was eliminated when a protease-deficient DegP S210A protein was overproduced. Our data showed that this rescue from lethality and a subsequent increase in mutant protein levels in the envelope did not lead to the proper assembly of the mutant proteins in the outer membrane. Rather, a detergent-soluble and thermolabile OmpF species resembling monomers accumulated in the mutants, and to a lesser extent in the parental strain, when DegP S210A was overproduced. Interestingly, this also led to the localization of a significant amount of mutant polypeptides to the inner membrane, where DegP S210A also fractionated. These results suggested that the DegP S210A -mediated rescue from toxicity involved preferential sequestration of misfolded OmpF monomers from the normal assembly pathway. |
| Databáze: | OpenAIRE |
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