Human DND1-RRM2 forms a non-canonical domain swapped dimer

RNA recognition motif (RRM) being the most abundant RNA binding domain in eukaryotes, is a major player in cellular regulation. Several variations in the canonical beta alpha beta beta alpha beta topology have been observed. We have determined the 2.3 angstrom crystal structure of the human DND1-RRM2 domain. The structure revealed an interesting non-canonical RRM fold, which is maintained by the formation of a 3D domain swapped dimer between beta(1) and beta(4) strands across protomers. We have delineated the structural basis of the stable domain swapped dimer formation using the residue level dynamics of protein explored by NMR spectroscopy and MD simulations. Our structural and dynamics studies substantiate major determinants and molecular basis for domain swapped dimerization observed in the RRM domain.

Automated summary

RNA recognition motif (RRM) is a commonly found RNA binding domain in eukaryotes, playing a crucial role in cellular regulation. The crystal structure of human DND1-RRM2 domain revealed a non-canonical fold maintained by a 3D domain swapped dimer between beta(1) and beta(4) strands. Structural and dynamics studies highlighted key determinants and molecular basis for the domain swapped dimerization observed in the RRM domain.