Project C01

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C1

Project Summary

Structural and functional features of a conserved DNA-binding domain in herpes viral proteins as a basis for innovative targeted therapies

Human herpesviruses establish lifelong persistent infections that can play a key role in tumorigenesis and provide the basis for severe disease resulting from viral reactivation. Herpesviral proteins interacting with viral DNA (vDBPs) are key players in latency establishment, maintenance, and regulation. In the herpesviral replication cycle, vDBPs can be classified as latent or immediate-early (IE) lytic proteins. Latent proteins such as KSHV LANA-1 and EBV EBNA-1 of the gamma herpesvirus subfamily mediate the replication of latent viral episomes and their partitioning to daughter cells during mitosis. On the other hand, lytic proteins such as HHV-6A IE2 and HCMV IE2 of the beta herpesvirus subfamily act as transcriptional activators of early or late viral promoters. 

Based on the crystal structures, the DNA-binding domains (DBDs) of LANA-1, EBNA-1, and HHV-6A IE2 share significant structural homology. AlphaFold models of HCMV IE2 predict a similar fold which indicates that DBD is conserved across herpesvirus families. According to the HerpesFolds database, the DBD structure might be conserved across the alpha herpesvirus subfamily as well. This significant structural homology could be an indication of conserved functions involving the viral lifecycle of herpesviruses. Hence, the vDBPs could be potential targets for therapeutic intervention. 

The two key herpes viral protein targets of this project are KSHV LANA-1 & HCMV IE2. In LANA-1, there are two caspase I and III cleavage sites. We hypothesize that a physiologically relevant domain is formed in the C-terminal domain (CTD) after being cleaved by caspase III, which we refer to as the extended CTD (eCTD). For IE2, we are interested in structure elucidation of the homologous CTD for structure-based drug development similar to EBNA-1 & LANA-1 inhibitors. 

The aim of the project is the structural and functional characterization of LANA DBD, eCTD, and HCMV-IE2 CTD alone and in complex with the viral DNA or small molecular inhibitors (SMIs) to develop innovative targeted therapy. We plan to employ conventional X-ray crystallography, in cellulo crystallization techniques, microcrystal electron diffraction (mED), and cryo-EM for structure elucidation. 

C1

References

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