Biophysical characterisation reveals structural disorder in the nucleolar protein, Dribble.
Dribble (DBE) is an essential protein in Drosophila that belongs to the evolutionarily conserved Krr1p protein family. Proteins in this family are localised in the cell nucleolus and are important for the processing of ribosomal RNAs. However, little is known about their structural and biophysical properties. We have expressed and purified full-length DBE protein from Escherichia coli. Consistent with the native role of DBE in RNA processing, recombinant DBE was shown to bind RNA homo-polymers in vitro. By bioinformatics, size-exclusion chromatography, equilibrium sedimentation analysis, controlled proteolysis, and a variety of spectroscopic techniques, we have found that DBE is a monomeric protein in solution containing both alpha- and beta-structures. Moreover, the structure of DBE is expanded and significantly disordered (approximately 45% disordered). Natively disordered proteins are thought to provide a disproportionately large surface area and structural plasticity for nucleic acid binding. We therefore propose that the presence of structural disorder is an important feature of DBE that facilitates the protein to interact with RNAs in the nucleolus.
Yiu
C-P Benny
CP
Laboratory of Drosophila Research, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China.
Beavil
Rebecca L
RL
Chan
H Y Edwin
HY
D000595:Amino Acid Sequence; D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D029721:Drosophila Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics; D004331:Drosophila melanogaster / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics; D011487:Protein Conformation; D012313:RNA / Q000737:chemistry; D016601:RNA-Binding Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics; D012997:Solvents / Q000737:chemistry
D029721:Drosophila Proteins; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D012997:Solvents; C434386:dbe protein, Drosophila; D012313:RNA