Structural Analysis of Structural Analysis of Maize Streak Virus Maize Streak Virus

Single and Geminate Single and Geminate ParticlesParticles

Structural Analysis of Structural Analysis of Maize Streak Virus Maize Streak Virus

Single and Geminate Single and Geminate ParticlesParticles

Robbie ReutzelUniversity of Florida

Molecular Structure Group

Robbie ReutzelUniversity of Florida

Molecular Structure Group

MSV Introduction:MSV Introduction:MSV Introduction:MSV Introduction:

Member of mastrevirusesTransmitted by leafhoppersMonopartite ssDNA genome (~2.7kb)Geminate particle consists of 110 copies of 28kDa coat proteinSingle, isometric (T=1) particles also found

Member of mastrevirusesTransmitted by leafhoppersMonopartite ssDNA genome (~2.7kb)Geminate particle consists of 110 copies of 28kDa coat proteinSingle, isometric (T=1) particles also found

MSV infected leaf Leafhopper, Cicadulina mbila

Geminate Model Geminate Model EvolutionEvolutionGeminate Model Geminate Model EvolutionEvolution

Negative Stain EM

Ping-Pong Model (1979)

Based on STNV (1984)

25Å (Zhang et al., 2001)

12Å (Jan.

2005)

MSV Geminate Particle MSV Geminate Particle Refinement:Refinement:MSV Geminate Particle MSV Geminate Particle Refinement:Refinement:

Assuming 52 point group

CTF CorrectionCTF CorrectionCTF CorrectionCTF 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

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: Geminate Particle: Latest ModelLatest Model

Geminate Particle: Geminate Particle: Latest ModelLatest Model

9.0Å Resolution

MSV Single Particle MSV Single Particle ModelModelMSV Single Particle MSV Single Particle ModelModel

What is the difference between the capsomers?

How are these particles related to the assembly mechanism?

10.2Å Resolution

Homology Modelling Homology Modelling and Manual Fittingand Manual Fitting

Homology Modelling Homology Modelling and Manual Fittingand Manual Fitting

MSV coat protein shares ~20% homology with STNV

Capsid models built and fitted manually using O

N

Geminate Capsid

ssDNA

Single Capsid

+

sg ssDNA

+

1

3

3

Proposed Assembly of MSV CapsidsProposed Assembly of MSV Capsids

2

1?

?

?

Phosphorylation Sulfation Glycosylation Truncation

2PentamericCapsomers

Infectious

Dead End?

Unanswered QuestionsUnanswered QuestionsUnanswered QuestionsUnanswered 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

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

AcknowledgementsAcknowledgements

University of Florida: Dr. Robert McKenna Dr. Mavis Agbandje-McKenna Antonette Bennett G. Javier Ortiz Eric Padron David Rodriguez

Purdue University/UCSD: Dr. Tim Baker Dr. Valorie Bowman Paul Chipman Dr. Norman H. Olson Dr. Wei Zhang Xing Zhang Xiaodong Yan

John Innes Centre: Dr. Margaret Boulton Samantha Bean