United Kingdom, United States, Russian Federation, 6items
Organization
Grant number
Country
Wellcome Trust
206377
United Kingdom
Wellcome Trust
103460
United Kingdom
National Institutes of Health/National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIH/NIAMS)
United States
Russian Foundation for Basic Research
16-34-60137
Russian Federation
Biotechnology and Biological Sciences Research Council
BB/L021250/1
United Kingdom
Wellcome Trust
108466
United Kingdom
Citation
Journal: Proc Natl Acad Sci U S A / Year: 2019 Title: Cryo-EM structure and in vitro DNA packaging of a thermophilic virus with supersized T=7 capsids. Authors: Oliver W Bayfield / Evgeny Klimuk / Dennis C Winkler / Emma L Hesketh / Maria Chechik / Naiqian Cheng / Eric C Dykeman / Leonid Minakhin / Neil A Ranson / Konstantin Severinov / Alasdair C ...Authors: Oliver W Bayfield / Evgeny Klimuk / Dennis C Winkler / Emma L Hesketh / Maria Chechik / Naiqian Cheng / Eric C Dykeman / Leonid Minakhin / Neil A Ranson / Konstantin Severinov / Alasdair C Steven / Alfred A Antson / Abstract: Double-stranded DNA viruses, including bacteriophages and herpesviruses, package their genomes into preformed capsids, using ATP-driven motors. Seeking to advance structural and mechanistic ...Double-stranded DNA viruses, including bacteriophages and herpesviruses, package their genomes into preformed capsids, using ATP-driven motors. Seeking to advance structural and mechanistic understanding, we established in vitro packaging for a thermostable bacteriophage, P23-45 of Both the unexpanded procapsid and the expanded mature capsid can package DNA in the presence of packaging ATPase over the 20 °C to 70 °C temperature range, with optimum activity at 50 °C to 65 °C. Cryo-EM reconstructions for the mature and immature capsids at 3.7-Å and 4.4-Å resolution, respectively, reveal conformational changes during capsid expansion. Capsomer interactions in the expanded capsid are reinforced by formation of intersubunit β-sheets with N-terminal segments of auxiliary protein trimers. Unexpectedly, the capsid has T=7 quasi-symmetry, despite the P23-45 genome being twice as large as those of known T=7 phages, in which the DNA is compacted to near-crystalline density. Our data explain this anomaly, showing how the canonical HK97 fold has adapted to double the volume of the capsid, while maintaining its structural integrity. Reconstructions of the procapsid and the expanded capsid defined the structure of the single vertex containing the portal protein. Together with a 1.95-Å resolution crystal structure of the portal protein and DNA packaging assays, these reconstructions indicate that capsid expansion affects the conformation of the portal protein, while still allowing DNA to be packaged. These observations suggest a mechanism by which structural events inside the capsid can be communicated to the outside.
Protocol: SINGLE WAVELENGTH / Monochromatic (M) / Laue (L): M / Scattering type: x-ray
Radiation wavelength
Wavelength: 0.92819 Å / Relative weight: 1
Reflection
Resolution: 1.95→94.2 Å / Num. obs: 105514 / % possible obs: 99.8 % / Redundancy: 6.8 % / CC1/2: 0.999 / Rmerge(I) obs: 0.103 / Net I/av σ(I): 6.2 / Net I/σ(I): 6.2
Reflection shell
Resolution: 1.95→1.98 Å / Redundancy: 7 % / Rmerge(I) obs: 1.199 / Mean I/σ(I) obs: 0.6 / Num. unique obs: 7752 / CC1/2: 0.626 / % possible all: 99.9
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Processing
Software
Name
Version
Classification
REFMAC
5.8.0238
refinement
DIALS
datareduction
Aimless
datascaling
MOLREP
phasing
Refinement
Resolution: 1.95→10 Å / Cor.coef. Fo:Fc: 0.96 / Cor.coef. Fo:Fc free: 0.949 / SU B: 10.818 / SU ML: 0.126 / Cross valid method: THROUGHOUT / ESU R: 0.298 / ESU R Free: 0.133 / Details: HYDROGENS HAVE BEEN ADDED IN THE RIDING POSITIONS
Rfactor
Num. reflection
% reflection
Selection details
Rfree
0.21613
1013
1 %
RANDOM
Rwork
0.15822
-
-
-
obs
0.15879
104315
99.58 %
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Solvent computation
Ion probe radii: 0.8 Å / Shrinkage radii: 0.8 Å / VDW probe radii: 1.2 Å