Structural insights into the U-box, a domain associated with multi-ubiquitination.

Ohi MD, Vander Kooi CW, Rosenberg JA, Chazin WJ, Gould KL
Nat Struct Biol. 2003 10 (4): 250-5

PMID: 12627222 · PMCID: PMC5881891 · DOI:10.1038/nsb906

The structure of the U-box in the essential Saccharomyces cerevisiae pre-mRNA splicing factor Prp19p has been determined by NMR. The conserved zinc-binding sites supporting the cross-brace arrangement in RING-finger domains are replaced by hydrogen-bonding networks in the U-box. These hydrogen-bonding networks are necessary for the structural stabilization and activity of the U-box. A conservative Val-->Ile point mutation in the Prp19p U-box domain leads to pre-mRNA splicing defects in vivo. NMR analysis of this mutant shows that the substitution disrupts structural integrity of the U-box domain. Furthermore, comparison of the Prp19p U-box domain with known RING-E2 complex structures demonstrates that both U-box and RING-fingers contain a conserved interaction surface. Mutagenesis of residues at this interface, while not perturbing the structure of the U-box, abrogates Prp19p function in vivo. These comparative structural and functional analyses imply that the U-box and its associated ubiquitin ligase activity are critical for Prp19p function in vivo.

MeSH Terms (15)

Amino Acid Sequence Drug Stability Hydrogen Bonding Models, Molecular Molecular Sequence Data Molecular Structure Mutation Nuclear Magnetic Resonance, Biomolecular Protein Structure, Tertiary RNA Splicing RNA Splicing Factors Saccharomyces cerevisiae Proteins Sequence Homology, Amino Acid Spliceosomes Ubiquitin

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