Abstract
The arginine repressor ofEscherichia coliis a classical feedback regulator, signalling the availability ofl-arginine inside the cell. It differs from most other bacterial repressors in functioning as a hexamer, but structural details have been lacking and its shares no clear sequence homologies with other transcriptional regulators. Analysis of the amino acid residue sequence and proteolytic cleavage pattern of the repressor was used to identify a region predicted to house the DNA-binding function. When this protein fragment is overexpressed from a clone of the corresponding gene fragment, it represses ornithine transcarbamylase levelsin vivo, and binds to the operator DNAin vitro, both in an arginine-independent manner. Sedimentation equilibrium and gel filtration indicate that the purified protein fragment is a monomer in solution. The results thus define the domain organization of the repressor at low resolution, suggesting that the N and C-terminal portions of the polypeptide chain are separated by a structural and functional border that decouples hexamerization and arginine binding from DNA binding.
Original language | English (US) |
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Pages (from-to) | 150-162 |
Number of pages | 13 |
Journal | Journal of Molecular Biology |
Volume | 254 |
Issue number | 2 |
DOIs | |
State | Published - Nov 24 1995 |
All Science Journal Classification (ASJC) codes
- Biophysics
- Structural Biology
- Molecular Biology
Keywords
- Allosteric repressors
- Functional domains
- Oligomeric structure
- Proteolysis
- Structural domains