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DNA recognition for virus assembly through multiple sequence-independent interactions with a helix-turn-helix motif

DOI: 10.1093/nar/gkv1467 DOI Help
PMID: 26673721 PMID Help

Authors: Sandra J. Greive (University of York) , Herman K. H. Fung (University of York) , Maria Chechik (University of York) , Huw T. Jenkins (University of York) , Stephen E. Weitzel (University of Oregon) , Pedro M. Aguiar (University of York) , Andrew S. Brentnall (University of York) , Matthieu Glousieau (University of York) , Grigory V. Gladyshev (Moscow State University) , Jennifer R. Potts (University of York) , Alfred A. Antson (University of York)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nucleic Acids Research

State: Published (Approved)
Published: December 2015

Open Access Open Access

Abstract: The helix-turn-helix (HTH) motif features frequently in protein DNA-binding assemblies. Viral pac site-targeting small terminase proteins possess an unusual architecture in which the HTH motifs are displayed in a ring, distinct from the classical HTH dimer. Here we investigate how such a circular array of HTH motifs enables specific recognition of the viral genome for initiation of DNA packaging during virus assembly. We found, by surface plasmon resonance and analytical ultracentrifugation, that individual HTH motifs of the Bacillus phage SF6 small terminase bind the packaging regions of SF6 and related SPP1 genome weakly, with little local sequence specificity. Nuclear magnetic resonance chemical shift perturbation studies with an arbitrary single-site substrate suggest that the HTH motif contacts DNA similarly to how certain HTH proteins contact DNA non-specifically. Our observations support a model where specificity is generated through conformational selection of an intrinsically bent DNA segment by a ring of HTHs which bind weakly but cooperatively. Such a system would enable viral gene regulation and control of the viral life cycle, with a minimal genome, conferring a major evolutionary advantage for SPP1-like viruses.

Subject Areas: Biology and Bio-materials

Instruments: I04-Macromolecular Crystallography

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