This domain is found in the putative ATP-dependent RNA helicase from Pyrococcus furiosus (PF2015) and similar archaeal proteins. PF2015 is a Hef helicase that processes flap- or fork-DNA structures. This protein shows an SF2 helicase domain in the N-terminal two-thirds and an XPF/Mus81-type nuclease domain in the C-terminal one-third. The SF2 helicase domain is organised into three structural subdomains. This entry represents the second of them, which is composed of six alpha-helices that are tightly assembled into a hydrophobic core. Its surface is positively charged, suggesting that it is a potential DNA binding region [1].

1: Crystal structure and functional implications of Pyrococcus furiosus hef helicase domain involved in branched DNA processing. Nishino T, Komori K, Tsuchiya D, Ishino Y, Morikawa K; Structure. 2005;13:143-153. PMID:15642269