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Mol Cell. 2009 Aug 28;35(4):454-66. doi: 10.1016/j.molcel.2009.08.006.

Common design principles in the spliceosomal RNA helicase Brr2 and in the Hel308 DNA helicase.

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Abteilung Zelluläre Biochemie, Max-Planck-Institut für Biophysikalische Chemie, Am Fassberg 11, D-37077 Göttingen, Germany.

Erratum in

  • Mol Cell. 2011 Feb 4;41(3):366.


Brr2 is a unique DExD/H box protein required for catalytic activation and disassembly of the spliceosome. It contains two tandem helicase cassettes that both comprise dual RecA-like domains and a noncanonical Sec63 unit. The latter may bestow the enzyme with unique properties. We have determined crystal structures of the C-terminal Sec63 unit of yeast Brr2, revealing three domains, two of which resemble functional modules of a DNA helicase, Hel308, despite lacking significant sequence similarity. This structural similarity together with sequence conservation between the enzymes throughout the RecA-like domains and a winged helix domain allowed us to devise a structural model of the N-terminal active cassette of Brr2. We consolidated the model by rational mutagenesis combined with splicing and U4/U6 di-snRNA unwinding assays, highlighting how the RecA-like domains and the Sec63 unit form a functional entity that appears suitable for unidirectional and processive RNA duplex unwinding during spliceosome activation and disassembly.

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