Crystallization and preliminary X-ray analysis of a U2AF⁶⁵ variant in complex with a polypyrimidine-tract analogue by use of protein engineering

The large subunit of the essential pre-mRNA splicing factor U2 auxiliary factor (U2AF⁶⁵) binds the polypyrimidine tract near the 3' splice site of pre-mRNA introns and directs the association of the U2 small nuclear ribonucleoprotein particle (U2 snRNP) of the spliceosome with the pre-mRNA. Protein engineering, in which the flexible linker region connecting tandem RNA-recognition motifs (RRMs) within the U2AF⁶⁵ RNA-binding domain was partially deleted, allowed successful crystallization of the protein-nucleic acid complex. Cocrystals of a U2AF⁶⁵ variant with a deoxyuridine dodecamer diffract X-rays to 2.9 Å resolution and contain one complex per asymmetric unit.