Translocation portals for the substrates and products of a viral transcription complex: the bluetongue virus core.
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.
Diprose
J M
JM
Division of Structural Biology, The Henry Wellcome Building for Genomic Medicine, Oxford University, Roosevelt Drive, Headington, Oxford OX3 7BN, UK.
Burroughs
J N
JN
Sutton
G C
GC
Goldsmith
A
A
Gouet
P
P
Malby
R
R
Overton
I
I
Ziéntara
S
S
Mertens
P P
PP
Stuart
D I
DI
Grimes
J M
JM
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
D010710:Phosphates; D012333:RNA, Messenger; D013431:Sulfates; D008274:Magnesium; D002118:Calcium