title: Translocation portals for the substrates and products of a viral transcription complex: the bluetongue virus core.
abstract: The bluetongue virus core is a molecular machine that simultaneously and repeatedly transcribes mRNA from 10 segments of viral double-stranded RNA, packaged in a liquid crystalline array. To determine how the logistical problems of transcription within a sealed shell are solved, core crystals were soaked with various ligands and analysed by X-ray crystallography. Mg(2+) ions produce a slight expansion of the capsid around the 5-fold axes. Oligonucleotide soaks demonstrate that the 5-fold pore, opened up by this expansion, is the exit site for mRNA, whilst nucleotide soaks pinpoint a separate binding site that appears to be a selective channel for the entry and exit of substrates and by-products. Finally, nucleotides also bind to the outer core layer, providing a substrate sink.
authors.affiliation: Division of Structural Biology, The Henry Wellcome Building for Genomic Medicine, Oxford University, Roosevelt Drive, Headington, Oxford OX3 7BN, UK.
authors.forename: J M
authors.initials: JM
authors.lastname: Diprose
authors.forename: J N
authors.initials: JN
authors.lastname: Burroughs
authors.forename: G C
authors.initials: GC
authors.lastname: Sutton
authors.forename: A
authors.initials: A
authors.lastname: Goldsmith
authors.forename: P
authors.initials: P
authors.lastname: Gouet
authors.forename: R
authors.initials: R
authors.lastname: Malby
authors.forename: I
authors.initials: I
authors.lastname: Overton
authors.forename: S
authors.initials: S
authors.lastname: Ziéntara
authors.forename: P P
authors.initials: PP
authors.lastname: Mertens
authors.forename: D I
authors.initials: DI
authors.lastname: Stuart
authors.forename: J M
authors.initials: JM
authors.lastname: Grimes
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D001820:Bluetongue virus / Q000235:genetics / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D018360:Crystallography, X-Ray; D008274:Magnesium / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D010710:Phosphates; D012333:RNA, Messenger; D013431:Sulfates; D008274:Magnesium; D002118:Calcium