tailieunhanh - Báo cáo khoa học: 3¢- to 5¢ DNA unwinding by TIP49b proteins

TIP49b (reptin) is an essential eukaryotic AAA+ ATPase involved in a variety of cellular processes, such as chromatin remodeling during double-strand break repair, transcriptional regulation, control of cell proliferation and small nucleolar RNA biogenesis. | ỊFEBS Journal 3 - to 5 DNA unwinding by TIP49b proteins Christophe Papin1 2 f Odile Humbert1 2 Anna Kalashnikova1 2 Kelvin Eckert3 Solange Morera3 Emmanuel Kas1 2 and Mikhail Grigoriev1 2 1 Laboratoire de Biologie Moleculaire Eucaryote Universite de Toulouse France 2 CNRS LBME Toulouse France 3 Laboratoire d Enzymologie et Biochimie Structurales Gif-sur-Yvette France Keywords AAA ATPases DNA binding reptin Rvb2p TIP49b TIP49b reptin is an essential eukaryotic AAA ATPase involved in a variety of cellular processes such as chromatin remodeling during doublestrand break repair transcriptional regulation control of cell proliferation Correspondence E. Kas or M. Grigoriev IBCG 118 route de Narbonne 31062 Toulouse Cedex 9 France Fax 33 0 5 61 33 58 86 Tel 33 0 5 61 33 59 19 33 0 5 61 33 59 59 E-mail grigor@ kas@ and small nucleolar RNA biogenesis. How it acts at the molecular level remains largely unknown. In the present study we show that both human TIP49b and its yeast orthologue Rvb2p cooperatively bind single-stranded DNA as monomers. Binding stimulates a slow ATPase activity and supports a 3 - to 5 DNA unwinding activity that requires a 3 -protruding tail 30 nucleotides. The data obtained indicate that DNA unwinding of 3 - to 5 junctions is also constrained by the length of flanking duplex DNA. By contrast TIP49b hexamers were found to be inactive for ATP hydrolysis These authors contributed equally to this work and DNA unwinding suggesting that in cells protein factors that remain unknown might be required to recycle these into an active form. ỶPresent address IGBMC UMR 7104 Illkirch France Structured digital abstract MINT-7804328 TIP49b uniprotkb Q4QQS4 and TIP49b uniprotkb Q4QQS4 bind MI 0407 by electron microscopy MI 0040 Received 4 January 2010 revised 9 April 2010 accepted 14 April 2010 MINT-7804638 tip49b uniprotkb Q4QQS4 and tip49b uniprotkb Q4QQS4 bind MI 0407 by molecular sieving MI 0071 doi .