NMR structure of the N-terminal-most HRDC1 domain of RecQ helicase from Deinococcus radiodurans.

The RecQ helicase from Deinococcus radiodurans (DrRecQ) distinguishes from other helicases in that it utilizes its three 'helicase and RNaseD C-terminal' domains (HRDC1, HRDC2 and HRDC3) to regulate its activity. These HRDC domains have different influence on the biochemical functions of DrRecQ. Currently, only the structure of HRDC3 was reported. Here, we determined the NMR structure of the N-terminal-most HRDC1, revealing a potential DNA binding domain. Fluorescence anisotropy assay indicates that HRDC1 has binding affinity weaker than 70 μM to all DNA substrates without any specificity. Biochemical assays suggested that HRDC1 cooperates with other domains to enhance full-length DrRecQ interactions with DNA.