title: Staphylococcus aureus DinG, a helicase that has evolved into a nuclease.
abstract: DinG (damage inducible gene G) is a bacterial superfamily 2 helicase with 5′→3′ polarity. DinG is related to the XPD (xeroderma pigmentosum complementation group D) helicase family, and they have in common an FeS (iron–sulfur)-binding domain that is essential for the helicase activity. In the bacilli and clostridia, the DinG helicase has become fused with an N-terminal domain that is predicted to be an exonuclease. In the present paper we show that the DinG protein from Staphylococcus aureus lacks an FeS domain and is not a DNA helicase, although it retains DNA-dependent ATP hydrolysis activity. Instead, the enzyme is an active 3′→5′ exonuclease acting on single-stranded DNA and RNA substrates. The nuclease activity can be modulated by mutation of the ATP-binding cleft of the helicase domain, and is inhibited by ATP or ADP, suggesting a modified role for the inactive helicase domain in the control of the nuclease activity. By degrading rather than displacing RNA or DNA strands, the S. aureus DinG nuclease may accomplish the same function as the canonical DinG helicase.
authors.affiliation: Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK.
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: McRobbie
authors.forename: Bjoern
authors.initials: B
authors.lastname: Meyer
authors.forename: Christophe
authors.initials: C
authors.lastname: Rouillon
authors.forename: Biljana
authors.initials: B
authors.lastname: Petrovic-Stojanovska
authors.forename: Huanting
authors.initials: H
authors.lastname: Liu
authors.forename: Malcolm F
authors.initials: MF
authors.lastname: White
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D004265:DNA Helicases / Q000235:genetics* / Q000378:metabolism; D005090:Exodeoxyribonucleases / Q000235:genetics* / Q000378:metabolism*; D013211:Staphylococcus aureus / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D005090:Exodeoxyribonucleases; D004265:DNA Helicases