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A binding motif for Siah ubiquitin ligase.

ABSTRACT: The Drosophila SINA (seven in absentia) protein and its mammalian orthologs (Siah, seven in absentia homolog) are RING domain proteins that function in E3 ubiquitin ligase complexes and facilitate ubiquitination and degradation of a wide range of cellular proteins, including beta-catenin. Despite these diverse targets, the means by which SINASiah recognize substrates or binding proteins has remained unknown. Here we identify a peptide motif (RPVAxVxPxxR) that mediates the interaction of Siah protein with a range of protein partners. Sequence alignment and mutagenesis scanning revealed residues that are important to this interaction. This consensus sequence correctly predicted a high-affinity interaction with a peptide from the cytoskeletal protein plectin-1 (residues 95-117). The unusually high-affinity binding obtained with a 23-residue peptide (K(Dapp) = 29 nM with SINA) suggests that it may serve as a useful dominant negative reagent for SINASiah proteins.

SUBMITTER: House CM

PROVIDER: S-EPMC152253 | biostudies-literature | 2003 Mar

REPOSITORIES: biostudies-literature

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A binding motif for Siah ubiquitin ligase.

House Colin M CM Frew Ian J IJ Huang Huei-Luen HL Wiche Gerhard G Traficante Nadia N Nice Edouard E Catimel Bruno B Bowtell David D L DD

Proceedings of the National Academy of Sciences of the United States of America 20030307 6

The Drosophila SINA (seven in absentia) protein and its mammalian orthologs (Siah, seven in absentia homolog) are RING domain proteins that function in E3 ubiquitin ligase complexes and facilitate ubiquitination and degradation of a wide range of cellular proteins, including beta-catenin. Despite these diverse targets, the means by which SINASiah recognize substrates or binding proteins has remained unknown. Here we identify a peptide motif (RPVAxVxPxxR) that mediates the interaction of Siah pro ...[more]

PMID: 12626763

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Project description:BackgroundThe RAS signaling pathway is a pivotal developmental pathway that controls many fundamental biological processes including cell proliferation, differentiation, movement and apoptosis. Drosophila Seven-IN-Absentia (SINA) is a ubiquitin E3 ligase that is the most downstream signaling "gatekeeper" whose biological activity is essential for proper RAS signal transduction. Vertebrate SINA homologs (SIAHs) share a high degree of amino acid identity with that of Drosophila SINA. SINA/SIAH is the most conserved signaling component in the canonical EGFR/RAS/RAF/MAPK signal transduction pathway.ResultsVertebrate SIAH1, 2, and 3 are the three orthologs to invertebrate SINA protein. SINA and SIAH1 orthologs are found in all major taxa of metazoans. These proteins have four conserved functional domains, known as RING (Really Interesting New Gene), SZF (SIAH-type zinc finger), SBS (substrate binding site) and DIMER (Dimerization). In addition to the siah1 gene, most vertebrates encode two additional siah genes (siah2 and siah3) in their genomes. Vertebrate SIAH2 has a highly divergent and extended N-terminal sequence, while its RING, SZF, SBS and DIMER domains maintain high amino acid identity/similarity to that of SIAH1. But unlike vertebrate SIAH1 and SIAH2, SIAH3 lacks a functional RING domain, suggesting that SIAH3 may be an inactive E3 ligase. The SIAH3 subtree exhibits a high degree of amino acid divergence when compared to the SIAH1 and SIAH2 subtrees. We find that SIAH1 and SIAH2 are expressed in all human epithelial cell lines examined thus far, while SIAH3 is only expressed in a limited subset of cancer cell lines.ConclusionThrough phylogenetic analyses of metazoan SINA and SIAH E3 ligases, we identified many invariant and divergent amino acid residues, as well as the evolutionarily conserved functional motifs in this medically relevant gene family. Our phylomedicinal study of this unique metazoan SINA/SIAH protein family has provided invaluable evolution-based support towards future effort to design logical, potent, and durable anti-SIAH-based anticancer strategies against oncogenic K-RAS-driven metastatic human cancers. Thus, this method of evolutionary study should be of interest in cancer biology.

Dataset Information

A binding motif for Siah ubiquitin ligase.

Publications

A binding motif for Siah ubiquitin ligase.

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