Kaposi’s sarcoma-associated herpesvirus ORF66 is essential for late gene expression and virus production via interaction with ORF34

Abstract

25Kaposi's sarcoma-associated herpesvirus (KSHV) is closely 26 associated with B-cell and endothelial cell malignancies. After the initial 27 infection, KSHV retains its viral genome in the nucleus of the host cell and 28 establishes a lifelong latency. During lytic infection, KSHV encoded lytic-related 29 proteins are expressed in a sequential manner and are classified as immediate 30 early, early, and late gene transcripts. The transcriptional initiation of KSHV late 31 genes is thought to require the complex formation of the virus specific pre-32 initiation complex (vPIC), which may consist of at least 6 transcription factors 33 (ORF18, 24, 30, 31, 34, and 66). However, the functional role of ORF66 in vPIC 34 during KSHV replication remains largely unclear. Here, we generated ORF66-35 deficient KSHV using a BAC system to evaluate its role during viral replication. 36While ORF66-deficient KSHV demonstrated mainly attenuated late gene 37 expression and decreased viral production, viral DNA replication was 38 unaffected. CHIP analysis showed that ORF66 bound to the promoters of late 39 gene (K8.1), but did not to those of latent gene (ORF72), immediate early gene 40 (ORF16) and early gene (ORF46/47). Furthermore, we found that three highly 41 conserved C-X-X-C sequences and a conserved leucine-repeat in the C-42 terminal region of ORF66 were essential for interaction with ORF34 and viral 43 production. The interaction between ORF66 and ORF34 occurred in a zinc-44 dependent manner. Our data support a model, in which ORF66 serves as a 45 critical vPIC component to promote late viral gene expression and viral 46 production. 47 IMPORTANCE 49 KSHV ORF66, a late gene product, and vPIC are thought to contribute 50 significantly to late gene expression during the lytic replication. However, the 51 physiological importance of ORF66 in terms of viral replication and vPIC 52 formation remains poorly understood. Therfore, we generated a ORF66-53 deficient BAC clone and evaluated its viral replication. Results showed that 54 ORF66 played a critical role in virus production and the transcription of L genes. 55To our knowledge, this is the first report showing ORF66 function in virus 56 replication using ORF66-deficient KSHV. We also clarified that ORF66 57 interacted with the transcription start site of K8.1 gene, a late gene. 58 Furthermore, we identified the ORF34-binding motifs in the ORF66 C-terminus: 59 three C-X-X-C sequences and a leucine-repeat sequence, which are highly 60 conserved among -and -herpesviruses. Our study provides insights into the 61 regulatory mechanisms of not only the late gene expression of KSHV but also 62 those of other herpesviruses. 63 64 65 replication. Finally, the transcriptional products of L genes, contribute to viral 90 particle formation by its encoding viral structure proteins (15). 91The viral pre-initiation complex (vPIC) has recently been proposed to 92 regulate L gene expression(16). vPIC is composed of several viral proteins 93 conserved among -and -herpesviruses (17), and has f...

Quantitative Proteomics Analysis of Lytic KSHV Infection in Human Endothelial Cells Reveals Targets of Viral Immune Modulation

“…Clusters 1 and 2 contain a total of 30 proteins, which increase in abundance from 36 to 60 h upon reactivation and are either insensitive ( Figure 6 C) or only mildly sensitive ( Figure 6 D) to PAA. Proteins from these clusters were previously reported to exhibit immediate-early expression kinetics, e.g., ORF45 or K8 ( Zhu et al., 1999 ), or early expression kinetics, e.g., ORF61, K5, or ORF66 ( Sun et al., 1999 ; Wang et al., 2010 ; Watanabe et al., 2020 ). The 15 proteins in cluster 3 also increase in abundance from 36 to 60 h but were more sensitive to PAA than those in cluster 2 ( Figure 6 E).…”

Biomolecular Fluorescence Complementation Profiling and Artificial Intelligence Structure Prediction of the Kaposi’s Sarcoma-associated Herpesvirus ORF18 and ORF30 Interaction

“…However, in order to reveal the real interactions between ORF18 and ORF30, characterization by X-ray crystallography is required. AI-prediction protein modelling has been used in our vPIC analysis, for assessment of appropriateness the real experimental data observed by pull-down and Immuno-precipitation assays [11]. It has been accepted that homology modeling is a useful method for predicting protein structure.…”

“…Therefore, the vPIC formation machinery and the precise roles of each vPIC component have remained largely unknown. In the case of KSHV, the vPIC is thought to consist of at least six viral components: ORF18, ORF24, ORF30, ORF31, ORF34, and ORF66 [7][8][9][10][11][12]. It has been reported that the KSHV ORF24 binds to the promoters of the KSHV late genes along with cellular RNAPII [7].…”

“…It has been reported that the KSHV ORF24 binds to the promoters of the KSHV late genes along with cellular RNAPII [7]. Furthermore, ORF34 is thought to act as a hub for interaction with other vPIC components including ORF18, ORF24, ORF31, and ORF66 [7][8][9][10][11][12]. Moreover, several studies have determined that ORF18 is also associated with ORF30, ORF31, ORF34, and ORF66 [7][8][9][10].…”

Herpes simplex virus 1 infection induces ubiquitination of UBE1a

“…UBE1a stably expressing HeLa cells were infected with HSV-1 and cultured for 12 hours for quantification of ICP5 mRNA expression. Reverse transcription reaction and real-time PCR were performed as described previously [28]. cDNAs, encoding ICP5 and Actin, were amplified with the following primer pairs:…”