High affinity dimerization by Ski involves parallel pairing of a novel bipartite alpha-helical domain
| Autor: | Deborah L. Shardy, Kenneth M. Blumenthal, Yonggang Ji, Edward Stavnezer, Guoxing Zheng, Steven B. Cohen |
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| Rok vydání: | 1998 |
| Předmět: |
Leucine zipper
Protein Conformation Dimer Proteolysis Molecular Sequence Data Biochemistry Protein Structure Secondary chemistry.chemical_compound Tandem repeat Proto-Oncogene Proteins medicine Animals Amino Acid Sequence Molecular Biology medicine.diagnostic_test Circular Dichroism Cell Biology DNA-Binding Proteins Crystallography chemistry Pairing Domain (ring theory) Bipartite graph Leucine Chickens Dimerization |
| Zdroj: | The Journal of biological chemistry. 272(50) |
| ISSN: | 0021-9258 |
| Popis: | c-Ski protein possesses a C-terminal dimerization domain that was deleted during the generation of v-ski, and has been implicated in the increased potency of c-ski in cellular transformation compared with the viral gene. The domain is predicted to consist of an extended α-helical segment made up of two motifs: a tandem repeat (TR) consisting of five imperfect repeats of 25 residues each and a leucine zipper (LZ) consisting of six heptad repeats. We have examined the structure and dimerization of TR or LZ individually or the entire TR-LZ domain. Using a quenched chemical cross-linking method, we show that the TR dimerizes with moderate efficiency (K d = 4 × 10−6 m), whereas LZ dimerizes poorly (K d > 2 × 10−5 m). However, the entire TR-LZ domain dimerizes efficiently (K d = 2 × 10−8 m), showing a cooperative effect of the two motifs. CD analyses indicate that all three proteins contain predominantly α-helices. Limited proteolysis of the TR-LZ dimer indicates that the two helical motifs are linked by a small loop. Interchain disulfide bond formation indicates that both the LZ and TR helices are oriented in parallel. We propose a model for the dimer interface in the TR region consisting of discontinuous clusters of hydrophobic residues forming “leucine buttons.” |
| Databáze: | OpenAIRE |
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