Eric Sonntag

Suche


C3 Regulation of nuclear egress of human cytomegalovirus through a multifunctional viral-cellular protein complex

Principal investigator
Manfred Marschall

Mentor
Heinrich Sticht

Formation and function of the cytomegalovirus-specific nuclear egress complex

 

As a characteristic for most DNA viruses, the human cytomegalovirus (HCMV) replicates genomes in the nucleus of the host cell. Thereafter, preformed viral capsids, packaged with genomic DNA, have to be translocated into the cytoplasm. Due to their large size, HCMV capsids are not able to pass the nuclear pore complex. For this reason, viral capsids have to bud through the nuclear membranes in order to gain access to the cytoplasm. The first step of this pathway is to traverse the inner nuclear membrane (INM). In order to bud in the INM, capsids must overcome the nuclear lamina, a dense meshwork of type V microfilaments. Therefore, a multimeric nuclear egress complex (NEC) is formed by viral and cellular proteins. The recruitment of protein kinases to this complex leads to a phosphorylation of the lamins and thereby to a partial disassembly of the lamina. Importantly, this disruption is restricted to distinct lamina depleted areas (LDAs) (Figure). For the disruption of the nuclear lamina, HCMV encodes two essential viral proteins that are core components of the nuclear egress complex (NEC): (i) the integral membrane protein pUL50, which is associated with the INM and (ii) pUL53, a phosphoprotein accumulated in the nucleus before attaining overall rim colocalization with pUL50.
The overall goal of this work is to elucidate the formation of the cytomegalovirus-specific NEC and characterize the functional role of specific NEC constituents. Hereby, we want to identify the mechanism of pUL50 translocation to the INM. Thus, we will also start to map the regions which are required for interactions of the particular NEC components. A specific focus will be on posttranslational modifications of the NEC proteins and their effect on NEC formation. Moreover, we will also analyze the diverse regulatory properties of the NEC. To this goal, knock-down experiments as well as the generation of fusion proteins will be conducted to analyze the NEC formation. In order to get further insights of the formation and function of the NEC in vivo, we will also test several recombinant murine CMVs (MCMVs) regarding their pathogenicity in mice. Therefore our experiments are focused on the effects of these interactions for the viral pathogenicity in several human and murine cells in order to identify a basis for antiviral compounds.

 

 

Figure: The postulated cytomegaloviral nuclear egress complex (NEC). Recruitment of viral and cellular components leads to partial disassembly of the nuclear lamina; so called lamin depleted areas (LDAs). Inner nuclear membrane (INM), lamin b receptor (LBR), nuclear pore complex (NPC), outer nuclear membrane (ONM), protein kinase c (PKC)

 

Publications

Milbradt, J., Kraut, A., Hutterer, C., Sonntag, E., Schmeiser, C., Ferro, M., Wagner, S., Lenac, T., Claus, C., Pinkert, S., Hamilton, S. T., Rawlinson, W. D., Sticht, H., Coute, Y. and Marschall, M. (2014): Proteomic Analysis of the Multimeric Nuclear Egress Complex of Human Cytomegalovirus. Mol Cell Proteomics. 2014 Aug;13(8):2132-2146. doi: 10.1074/mcp.M113.035782

Thomas M, Sonntag E, Müller R, Schmidt S, Zielke B, Fossen T, Stamminger T.: pUL69 of Human Cytomegalovirus Recruits the Cellular Protein Arginine Methyltransferase 6 via a Domain That Is Crucial for mRNA Export and Efficient Viral Replication. J Virol. 2015 Sep 15;89(18):9601-15. doi: 10.1128/JVI.01399-15. Epub 2015 Jul 15.

 

Presentations

October 2016 8th Annual Retreat, Erlangen School of Molecular Communication, Schloss Schney, Lichtenfels, Germany
”Functional importance of cellular CDKs and PKCα for nuclear egress of cytomegaloviral capsids”
Talk
     
October 2015 2nd International SFB 796 Conference: Mechanisms of microbial host cell manipulation: From plants to humans, Erlangen, Germany
”The cytomegalovirus nuclear egresss protein pUL50 defines the assembly of a multimeric viral-cellular egress complex”
Poster
     
July 2015 7th Annual Retreat, Erlangen School of Molecular Communication, Schloss Hirschberg, Beilngries, Germany
”Understanding the function by mapping the interaction domains of the cytomegalovirus-specific nuclear egress complex”
Talk
     
July 2015 Methods in Molecular Virology, Institute of Virology, Erlangen, Germany
"Cytomegalovirus pUL50 is the multi-interacting determinant of the nuclear egress complex (NEC) that recruits cellular accessory NEC components"
Talk
     
April 2015 15th International CMV/Beta Herpes Virus Workshop Brisbane 2015, Brisbane, Australia
"Understanding the function by mapping the interaction domains of the cytomegalovirus-specific nuclear egress complex"
Talk
     
November 2014 2nd Waldthausen Castle Symposium, Margaret Gladys Smith 60th Anniversary of Cytomegalovirus Isolation, Budenheim, Germany
Formation of the cytomegaloviral-specific nuclear egress complex
Poster
     
July 2014 6th Annual Retreat, Erlangen School of Molecular Communication, Kloster Banz, Bad Staffelstein, Germany
Formation of the cytomegaloviral-specific nuclear egress complex
Poster
     

Awards

Best Talk Award

third place

7th Annual Retreat, Erlangen School of Molecular Communication, Schloss Hirschberg, Beilngries, Germany, July 2015
"Understanding the function by mapping the interaction domains of the cytomegalovirus-specific nuclear egress complex"

Best Poster Award

first place

6th Annual Retreat, Erlangen School of Molecular Communication Kloster Banz, Bad Staffelstein, Germany, July 2014
"Formation of the cytomegaloviral-specific nuclear egress complex"

Best Poster Award

first place

2nd Waldthausen Castle Symposium, Margaret Gladys Smith 60th Anniversary of Cytomegalovirus Isolation, Budenheim, Germany, November 2014
Formation of the cytomegaloviral-specific nuclear egress complex"