Winged helix proteins

The winged helix proteins constitute a subfamily within the large ensemble of helix-turn-helix proteins. Since the discovery of the winged helix/fork head motif in 1993, a large number of topologically related proteins with d iverse biological functions have been characterized by X-ray crystallograph y and solution NMR spectroscopy. Recently, a winged helix transcription fac tor (RFX1) was shown to bind DNA using unprecedented interactions between o ne of its eponymous wings and the major groove. This surprising observation suggests that the winged helix proteins can be subdivided into at least tw o classes with radically different modes of DNA recognition.