Sascha Walzer

Suche


A3 Structural biology of plant potyvirus and cytomegalovirus effector proteins

Principal investigator
Yves Muller

Mentor
Uwe Sonnewald

Structural studies of potyviral capsid proteins and plant chaperones

Being one of the largest genera of plant viruses with over 100 recognized members, the infection of mono- and dicotyledonous plant crops by poytviruses leads to severe economic repercussions; despite that, remarkably little is known about structure-function relationships in potyviral proteins - in fact, no structures of potyviral effector proteins have been solved to date.
Recently, it has been shown that interactions of the potyvirus capsid protein (CP) with Hsp40-type plant chaperones are essential for viral infectivity as they shuffle CP to the host cell's Hsp70 machinery, thereby preventing CP from prematurely aborting viral replication via association to viral RNA. Initial studies of Hsp40-type capsid protein interacting proteins (CPIPs) isolated from Nicotiana tabacum demonstrated formation of a stable complex with CP of potato virus Y, the eponymous member of the potyvirus genus. First crystallization trials of NtCPIPs have been set up and so far only yielded crystals of a truncated NtCPIP variant; however, it is essential to not only obtain structures of full-length CPIPs but also of potyvirus CPs and of various CP-CPIP complexes.
Therefore, this project's goals include obtaining the first crystal structure of a potyvirus CP, as well as fine-mapping the interactions between plant CPIP chaperones and CP, as understanding the atomic determinants of the CP-CPIP interaction might lead to new routes for combatting potyviruses. To accomplish those objectives we will rely on various biochemical and biophysical methods besides x-ray crystallography, high-resolution mass spectrometry in particular.

Figure: Potyviruses feature a rod-shaped, flexuous capsid up to 900 nm in length, consisting of approx. 2000 copies of the capsid protein. After infection, uncoating of the viral 10 kb ss(+)RNA genome allows for genome replication and replication-associated translation of viral genes. Expressed CP in turn binds to viral RNA, obstructing further translation. At early stages of viral replication, Hsp40-type CPIPs shuffle CPs to the Hsp70 machinery, causing CP degradation via ubiquitinylation and ensuring continued genome replication and translation. At later stages, CP is abundant and depletes CPIP, effectively stopping replication-associated translation and causing the infection to proceed to the assembly phase.

 

Publications

Walzer SA, Egerer-Sieber C, Sticht H, Sevvana M, Hohl K, Milbradt J, Muller YA, Marschall M (2015). Crystal Structure of the Human Cytomegalovirus pUL50-pUL53 Core Nuclear Egress Complex Provides Insight into a Unique Assembly Scaffold for Virus-Host Protein Interactions. J Biol Chem. 2015 Oct 2. [Epub ahead of print]

 

Presentations

October 2016 8th Annual Retreat, Erlangen School of Molecular Communication, Schloss Schney, Lichtenfels, Germany
“Structural studies of potyviral capsid proteins and plant chaperones”
Talk
     
October 2015 2nd International SFB 796 Conference: Mechanisms of microbial host cell manipulation: From plants to humans, Erlangen, Germany
“Crystal Structure of the Human Cytomegalovirus pUL50/53 Core Nuclear Egress Complex”
Poster
     
September 2015 18th Heart of Europe Bio-Crystallography Meeting, Kutná Hora, Czech Republic
“Towards the Structure of HCMV pUL50/53”
Talk
     
July 2015 7th Annual Retreat, Erlangen School of Molecular Communication, Schloss Hirschberg, Beilngries, Germany
“Crystallographic studies on HCMV pUL50/53”
Poster
     
July 2014 6th Annual Retreat, Erlangen School of Molecular Communication, Kloster Banz, Bad Staffelstein, Germany
“Structural Studies on Potyvirus Effector Proteins”
Talk
     
July 2013 5th Annual Retreat, Erlangen School of Molecular Communication, Kloster Banz, Bad Staffelstein, Germany
“Structural Studies on Plant Potyvirus Effector Proteins”
Talk
     
June 2013 Workshop 'Diffraction Data Collection Using Synchrotron Radiation', Helmholtz-Zentrum Berlin, Berlin, Germany
“Structural Studies on Potyviral Capsid Proteins”
Poster
     
March 2013 1st ECROPS Retreat, Beilngries, Germany
“Mass Spectrometry and Crystallographic Studies on Plant Potyvirus Effector Proteins”
Poster
     

 

Awards

Best Poster Award

first place

2nd International SFB 796 Conference: Mechanisms of viral host cell manipulations: from plants to humans, Erlangen, Germany, October 2015
“Crystal Structure of the Human Cytomegalovirus pUL50/53 Core Nuclear Egress Complex”