InterPro domain: IPR010997

This superfamily represents the HRDC (helicase and RNaseD C-terminal) domain, which comprises two orthogonally packed alpha-hairpin subdomains, and is involved in interactions with DNA and protein.

The HRDC (helicase and RNaseD C-terminal) domain is found at the C terminus of many RecQ helicases, including the human Werner and Bloom syndrome proteins [ 1 ]. RecQ helicases have been shown to unwind DNA in an ATP-dependent manner. The structure of the HRDC domain consists of a 4-5 helical bundle of two orthogonally packed alpha-hairpins, and as such it resembles auxiliary domains in bacterial DNA helicases and other proteins that interact with nucleic acids. A positively charged region on the surface of the HRDC domain is able to interact with DNA.

The HRDC domain is also present in eukaryotic and archaeal RNA polymerase II subunit RBP4, the N-terminal of which forms a heterodimerisation alpha-hairpin [ 2 , 3 ].

1. The three-dimensional structure of the HRDC domain and implications for the Werner and Bloom syndrome proteins. Structure 7, 1557-66
2. Structures of complete RNA polymerase II and its subcomplex, Rpb4/7. J. Biol. Chem. 280, 7131-4
3. Structure of an archaeal homolog of the eukaryotic RNA polymerase II RPB4/RPB7 complex. Mol. Cell 8, 1137-43