Backbone Dynamics and Model-Free Analysis of the RecQ C-Terminal Domain of Bloom Syndrome Protein

Abstract

Bloom syndrome protein (BLM) is one of RecQ helicases, which are conserved DNA unwinding enzymes in DNA metabolisms. The RecQ C-terminal domain (RQC) of BLM is a winged-helix motif, which recognizes various DNA structures. BLM RQC mediates electrostatic interactions with duplex DNA by using polar residues in the ?-wing and α2?α3 loop. In order to understand the dynamic properties of RQC for recognizing its substrate DNA, we measured 15N spin relaxation parameters of the protein and performed model-free analysis. Our results showed that the ?-wing region, which is used for the strand separation, has flexible backbone structure. The α2?α3 loop, the binding surface of the DNA major groove, was found to be relatively rigid. Our results contribute to a better understanding of molecular basis of BLM RQC?DNA interaction.