A Broad Range of Conformations
Contribute to the Solution
Ensemble of the Essential Splicing Factor U2AF<sup>65</sup>
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Abstract
U2AF<sup>65</sup> is essential for pre-mRNA splicing
in most eukaryotes.
Two consecutive RNA recognition motifs (RRM) of U2AF<sup>65</sup> recognize
a polypyrimidine tract at the 3′ splice site. Here, we use
small-angle X-ray scattering to demonstrate that the tandem U2AF<sup>65</sup> RRMs exhibit a broad range of conformations in the solution
ensemble. The majority of U2AF<sup>65</sup> conformations exhibit
few contacts between the RRMs, such as observed in the crystal structure.
A subpopulation adopts tight inter-RRM contacts, such as independently
reported based on paramagnetic relaxation enhancements. These complementary
structural methods demonstrate that diverse splice sites have the
opportunity to select compact or extended inter-RRM proximities from
the U2AF<sup>65</sup> conformational pool