# In situ atomic structures of the Kaposi's sarcoma-associated herpesvirus portal-terminase complex and glycoproteins > **NIH NIH R01** · UNIVERSITY OF CALIFORNIA LOS ANGELES · 2023 · $416,812 ## Abstract Project Summary/Abstract Kaposi's sarcoma (KS) is the most common malignancy associated with infection by human immunodeficiency virus (HIV). As a cancer of endothelial origin that typically grows under the skin or mucous membranes, KS in AIDS patients mostly manifests as oral lesions. Kaposi's sarcoma-associated herpesvirus (KSHV), a member of the gammaherpesvirus subfamily of the Herpesviridae family, has been shown to be an etiologic agent of all forms of KS, primary effusion lymphoma, and multicentric Castleman's disease. Currently, no drugs specifically targeting lytic replication of KSHV are available. Additionally, atomic structures of KSHV viral genome packaging/ejection machinery and fusion-mediating glycoproteins needed for rational design of antiviral drugs and vaccines are unavailable. The prior four-years' funding of this multiple principal investigator (MPI) R01 project has led to the publication of the atomic structure of the KSHV capsid in Nature. Structure-guided mutagenesis studies have identified amino acid interactions among capsid proteins that are essential to capsid assembly and informed the design of small peptide mimics that inhibited viral maturation. Jointly, the MPIs' groups also published the first atomic model of the KSHV DNA-packaging portal complex and capsid associated tegument complexes in Cell. Preliminary data for this renewal application have established the feasibility of obtaining in situ structures of genome-packaging portal-terminase complex and the cell-entry glycoprotein B (gB) in both pre-fusion and post-fusion conformations. These portal protein and envelope glycoprotein structures and structure-guided mutagenesis results have led to three hypotheses: (1) the portal- associated proteins and terminase interactions are vital to KSHV genome encapsidation; (2) the interactions and conformational changes among envelope glycoproteins are required for KSHV fusion with host cells during cell entry; and (3) such interactions revealed in atomic structures can help design inhibitors and vaccines against KSHV lytic infection. The studies described in this application will test the above hypotheses by taking advantage of technology breakthroughs in high-resolution cryoEM and KSHV mutagenesis already demonstrated in the two MPIs' labs in the current funding cycle. In Aim 1, we will determine the in situ structures of KSHV portal-associated proteins and the terminase to ~3Å by cryoEM. From these structures, we will derive atomic models and identify amino- acid residues within 6 Å of interacting proteins (i.e., residues vital to DNA packaging and ejection). In Aim 2, we will determine the structures of major envelope glycoproteins to ~3Å. Specifically, we will characterize the pre- fusion and post-fusion states of gB and the interactions of gH/gL, gM/gN, and K8.1A with their binding partners. In Aim 3, we will refine our structural interpretation through structure-guided mutagenesis and identify target sites for inhib... ## Key facts - **NIH application ID:** 10690566 - **Project number:** 5R01DE025567-09 - **Recipient organization:** UNIVERSITY OF CALIFORNIA LOS ANGELES - **Principal Investigator:** TING-TING WU - **Activity code:** R01 (R01, R21, SBIR, etc.) - **Funding institute:** NIH - **Fiscal year:** 2023 - **Award amount:** $416,812 - **Award type:** 5 - **Project period:** 2015-12-01 → 2025-08-31 ## Primary source NIH RePORTER: https://reporter.nih.gov/project-details/10690566 ## Citation > US National Institutes of Health, RePORTER application 10690566, In situ atomic structures of the Kaposi's sarcoma-associated herpesvirus portal-terminase complex and glycoproteins (5R01DE025567-09). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10690566. Licensed CC0. --- *[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*