Structural Analysis of
Maize Streak Virus Single
and Geminate Particles
Robbie Reutzel
University of Florida
Molecular Structure Group
MSV Introduction:
Member of mastreviruses
Transmitted by leafhoppers
Monopartite ssDNA genome (~2.7kb)
Geminate particle consists of 110 copies of 28kDa coat
protein
Single, isometric (T=1) particles also found
MSV infected leaf
Leafhopper, Cicadulina mbila
Geminate Model Evolution
Negative
Stain EM
Ping-Pong
Model
(1979)
Based on
STNV
(1984)
25Å
(Zhang et
al., 2001)
12Å (Jan.
2005)
MSV Geminate Particle
Refinement:
Assuming 52 point group
CTF Correction
Not able to collect SAXS (small angle x-ray scattering)
data
Used “bootstrapping” technique outlined in the EMAN
FAQ
Micrographs from 1.0-3.6 defocus were used
Geminate Particle: Latest
Model
9.0Å Resolution
MSV Single Particle Model
What is the difference
between the capsomers?
How are these particles
related to the assembly
mechanism?
10.2Å Resolution
Homology Modelling and
Manual Fitting
MSV coat protein
shares ~20% homology
with STNV
Capsid models built
and fitted manually
using O
Proposed Assembly of MSV Capsids
Phosphorylation
Sulfation
Glycosylation
Truncation
Geminate Capsid
Single Capsid
1
?
1
N
Infectious
Dead
End?
3
?
3
2
Pentameric
Capsomers
+
+
sg ssDNA
2
?
ssDNA
Unanswered Questions
What are the connections along the geminate
particle equator?
What are the differences in coat protein
conformation between single and geminate
particles?
Very interested in using Helix and Foldhunter
Acknowledgements
University of Florida: Dr. Purdue University/UCSD:
Robert McKenna
Dr.
Mavis Agbandje-McKenna
Antonette Bennett
G. Javier Ortiz
Eric Padron
David Rodriguez
John Innes Centre:
Dr. Margaret Boulton
Samantha Bean
Dr. Tim Baker
Dr.
Valorie Bowman
Paul
Chipman
Dr.
Norman H. Olson
Dr.
Wei Zhang
Xing
Zhang
Xiaodong Yan