Structural features of the plasmid pMV158-encoded transcriptional repressor CopG, a protein sharing similarities with both helix-turn-helix and beta-sheet DNA binding proteins
| Autor: | P, Acebo, M, García de Lacoba, G, Rivas, J M, Andreu, M, Espinosa, G, del Solar |
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| Rok vydání: | 1998 |
| Předmět: |
DNA Replication
Models Molecular Circular Dichroism Molecular Sequence Data DNA Helicases Proteins Streptococcus Protein Structure Secondary Protein Structure Tertiary DNA-Binding Proteins Molecular Weight Repressor Proteins Bacterial Proteins Spectrometry Mass Matrix-Assisted Laser Desorption-Ionization Trans-Activators Point Mutation Amino Acid Sequence Sequence Alignment Half-Life Helix-Turn-Helix Motifs Plasmids Sequence Deletion |
| Zdroj: | Proteins. 32(2) |
| ISSN: | 0887-3585 |
| Popis: | The small transcriptional repressor CopG protein (45 amino acids) encoded by the streptococcal plasmid pMV158 was purified to near homogeneity. Gel filtration chromatography and analytical ultracentrifugation showed that the native protein is a spherical dimer of identical subunits. Circular dichroism measurements of CopG indicated a consensus average content of more than 50% alpha-helix and 10-35% beta-strand and turns, which is compatible with the predicted secondary structure of the protein. CopG exhibited a prolonged intracellular half-life, but deletions in regions other than the C-terminal affected the global structure of the protein, severely reducing the half-lives of the CopG variants. This indicates that CopG has a compact structure, perhaps constituted by a single domain. Molecular modeling of CopG showed a good fitting between the helix-turn-helix motifs of well-known repressor proteins and a bihelical unit of CopG. However, modeling of CopG with ribbon-helix-helix class of DNA binding proteins also exhibited an excellent fit. Eleven out of the 12 replicons belonging to the pMV158 plasmid family could also encode Cop proteins, which share features with both helix-turn-helix and beta-sheet DNA binding proteins. |
| Databáze: | OpenAIRE |
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