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Structural and functional analyses of mutant Fur proteins with impaired regulatory function
A M Wertheimer1, M E Tolmasky, L A Actis
1Department of Molecular Microbiology and Immunology, School of Medicine, Oregon Health Sciences University, Portland 97201-3098.
Journal of Bacteriology
|August 1, 1994
Summary
This study characterized Vibrio anguillarum Fur mutants, revealing that specific mutations impair Fur activity or prevent protein synthesis. Both mutants showed instability with frequent reversion to the wild type.
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Genetics
Background:
- The ferric uptake regulator (Fur) protein is crucial for regulating iron homeostasis in many bacteria, including Vibrio anguillarum.
- Understanding Fur protein function is essential for controlling bacterial infections and understanding virulence mechanisms.
Purpose of the Study:
- To characterize two Vibrio anguillarum Fur mutants, 775met9 and 775met11, to understand the impact of specific mutations on Fur activity and protein stability.
- To investigate the structural and functional consequences of mutations within the Fur protein.
Main Methods:
- Site-directed mutagenesis was used to create specific mutations in the Vibrio anguillarum Fur gene.
- Functional assays were performed to assess the activity of the mutated Fur proteins.
- Computer-based structural analysis was employed to predict the effects of mutations on protein conformation.
- Stability assays were conducted to monitor the reversion rates of the generated mutants.
Main Results:
- Mutant 775met9 exhibited impaired Fur activity due to a D to G substitution at position 104 in the carboxy terminus, predicted to perturb alpha-helix structure and protein conformation.
- Mutant 775met11 resulted in no protein synthesis due to a mutation in the start codon.
- Both Fur mutants demonstrated instability, with frequent spontaneous reversion to the wild-type phenotype observed.
Conclusions:
- Specific mutations in the Vibrio anguillarum Fur gene can lead to loss of function or abrogation of protein synthesis.
- The carboxy terminus of the Fur protein is critical for its activity and proper conformation.
- The instability and frequent reversion of these mutants highlight the selective pressures and genetic mechanisms involved in maintaining wild-type function in Vibrio anguillarum.