Characterization of Cullin-box Sequences That Direct Recruitment of Cul2-Rbx1 and Cul5-Rbx2 Modules to Elongin BC-based Ubiquitin Ligases
| Autor: | Selene K. Swanson, Joan W. Conaway, Ronald C. Conaway, Michael P. Washburn, William B. Redwine, Skylar Martin-Brown, William D. Bradford, Nawel Mahrour, Laurence Florens, Karen Staehling-Hampton |
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| Rok vydání: | 2008 |
| Předmět: |
Ubiquitin-Protein Ligases
Amino Acid Motifs Elongin DNA-Directed DNA Polymerase Biochemistry Cell Line Protein structure Ubiquitin Multienzyme Complexes Humans Molecular Biology biology Cullin Proteins Cell Biology Protein Structure Tertiary Ubiquitin ligase Cell biology Von Hippel-Lindau Tumor Suppressor Protein biology.protein Carrier Proteins Sequence motif CUL5 Cullin Transcription Factors |
| Zdroj: | Journal of Biological Chemistry. 283:8005-8013 |
| ISSN: | 0021-9258 |
| Popis: | The Elongin BC-box protein family includes the von Hippel-Lindau tumor suppressor and suppressor of cytokine signaling proteins, which are substrate recognition subunits of structurally related classes of E3 ubiquitin ligases composed of Elongin C-Elongin B-Cullin 2-Rbx1 (Cul2 ubiquitin ligases) or of Elongin C-Elongin B-Cullin 5-Rbx2 (Cul5 ubiquitin ligases). The Elongin BC complex acts as an adaptor that links a substrate recognition subunit to heterodimers of either Cullin 2 (Cul2) and RING finger protein Rbx1 or Cullin 5 (Cul5) and Rbx2. It has been shown ( Kamura, T., Maenaka, K., Kotoshiba, S., Matsumoto, M., Kohda, D., Conaway, R. C., Conaway, J. W., and Nakayama, K. I. (2004) Genes Dev. 18, 3055-3065 ) that interaction of BC-box proteins with their cognate Cul-Rbx module is determined by specific regions, called Cul2- or Cul5-boxes, located immediately downstream of their BC-boxes. Here, we investigate further the mechanisms governing assembly of BC-box proteins with their specific Cul-Rbx modules. Through purification and characterization of a larger collection of BC-box proteins that serve as substrate recognition subunits of Cul2 and Cul5 ubiquitin ligases and through structure-function studies, we define Cul2- and Cul5-boxes in greater detail. Although it previously appeared that there was little sequence similarity between Cul5- and Cul2-box motifs, analyses of newly identified BC-box proteins reveal that residues conserved in the Cul2-box represent a subset of those conserved in the Cul5-box. The sequence motif LPPhiP, which is conserved in most Cul5-boxes and has been suggested to specify assembly of Cul5 ligases, is compatible with Cul2 interaction. Finally, the spacing between BC- and Cullin-boxes is much more flexible than has been appreciated and can vary from as few as 3 and as many as approximately 80 amino acids. Taken together, our findings shed new light on the mechanisms by which BC-box proteins direct recruitment of Cullin-Rbx modules during reconstitution of ubiquitin ligases. |
| Databáze: | OpenAIRE |
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