The importance of the linker connecting the repeats of the c-Myb oncoprotein may be due to a positioning function
| Autor: | Anne Bostad Hegvold, Odd S. Gabrielsen |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 1996 |
| Předmět: |
Models
Molecular Oncogene Proteins Stereochemistry Mutant Biology Protein Structure Secondary chemistry.chemical_compound Proto-Oncogene Proteins c-myb Polydeoxyribonucleotides Proto-Oncogene Proteins Genetics Animals Chymotrypsin MYB Trypsin Conserved Sequence Helix-Turn-Helix Motifs Repetitive Sequences Nucleic Acid chemistry.chemical_classification Acrylamide Acrylamides Binding Sites Proteolytic enzymes Tryptophan Amino acid DNA-Binding Proteins Spectrometry Fluorescence chemistry Biochemistry Mutagenesis Site-Directed Trans-Activators Electrophoresis Polyacrylamide Gel DNA Probes Linker Chickens DNA Research Article Transcription Factors |
| Popis: | The DNA-binding domain of the oncoprotein c-Myb consists of three imperfect tryptophan-rich repeats, R1, R2 and R3. Each repeat forms an independent minidomain with a helix‐turn‐helix related motif and they are connected by linkers containing highly conserved residues. The location of the linker between two DNA-binding units suggests a function analogous to a dimerisation motif with a critical role in positioning the recognition helices of each mini-domain. Mutational analysis of the minimal DNA-binding domain of chicken c-Myb (R2 and R3), revealed that besides the recognition helices of each repeat, the linker connecting them was of critical importance in maintaining specific DNAbinding. A comparison of several linker sequences from different Myb proteins revealed a highly conserved motif of four amino acids in the first half of the linker: LNPE (L138 to E141 in chicken c-Myb R2R3). Substitution of residues within this sequence led to reduced stability of protein‐DNA complexes and even loss of DNAbinding. The two most affected mutants showed increased accessibility to proteases, and fluorescence emission spectra and quenching experiments revealed greater average exposure of tryptophans which suggests changes in conformation of the proteins. From the structure of R 2 R 3 we propose that the LNPE motif provides two functions: anchorage to the first repeat (through L) and determination of the direction of the bridge to the next repeat (through P). |
| Databáze: | OpenAIRE |
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