Kaposi’s Sarcoma-Associated Herpesvirus ORF7 Is Essential for Virus Production

Iwaisako, Yuki; Watanabe, Tadashi; Hanajiri, Mizuki; Sekine, Yoshifumi; Fujimuro, Masahiro

doi:10.3390/microorganisms9061169

Cited by 9 publications

(37 citation statements)

References 37 publications

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“…Since the machinery for viral genome cleavage and packaging into capsids by the viral terminase does not exist in the host cells, this machinery may be a promising target for the development of antiviral drugs with high virus specificity. We have previously reported that KSHV ORF7, ORF29, and ORF67.5 form a tripartite complex, in which ORF7 functions as a center hub molecule (26). Similarly, HSV-1 UL15 (KSHV ORF29 homolog), UL28 (KSHV ORF7 homolog), and UL33 (KSHV ORF67.5 homolog) form a tripartite complex, and hexameric ring of this tripartite complex becomes an HSV-1 terminase (22).…”

Section: Discussionmentioning

confidence: 99%

“…WT-BAC16 was a kind gift from Jae U. Jung and Dr. Kevin Brulois. ORF7-fsKO-BAC16, ORF7-stKO-BAC16, ORF7-fsKO Rev-BAC16, and ORF7-stKO Rev-BAC16 were previously constructed (26, 42). The transfected cells were selected under 1 mg/mL of hygromycin B (Wako, Osaka, Japan) to establish Dox-inducible recombinant KSHV-producing cell lines (WT-iSLK, ORF7-fsKO-iSLK, ORF7-stKO-iSLK, ORF7-fsKO Rev-iSLK, and ORF7-stKO Rev-iSLK, ORF7&17-DKO-iSLK, and ORF7 mC1H1-iSLK).…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…We found that ORF7 was dispensable for viral DNA replication but was essential for virus production (26). Furthermore, ORF7 interacted with ORF29 and ORF67.5, which are homologs of HSV-1 UL15 and UL33, respectively (26). However, it still remains unknown whether ORF7 is a component of the KSHV terminase complex.…”

Section: Introductionmentioning

confidence: 99%

“…interacted with ORF29 and ORF67.5, which are homologs of HSV-1 UL15 and UL33, respectively (26). However, it still remains unknown whether ORF7 is a component of the KSHV terminase complex.…”

Section: Introductionmentioning

confidence: 99%

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The contribution of Kaposi’s sarcoma-associated herpesvirus ORF7 and its zinc-finger motif to viral genome cleavage and capsid formation

Iwaisako

Watanabe

Sekine

et al. 2022

Preprint

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Kaposi’s sarcoma-associated herpesvirus (KSHV) is the causative agent of endothelial and B cell malignancies. During KSHV lytic infection, lytic-related proteins are synthesized, viral genomes are replicated as a tandemly repeated form, and subsequently, capsids are assembled. The herpesvirus terminase complex is proposed to package an appropriate genome unit into an immature capsid, by cleavage of terminal repeats (TRs) flanking tandemly linked viral genomes. Although the mechanism of capsid formation in α- and β-herpesviruses are well-studied, in KSHV, it remains largely unknown. It has been proposed that KSHV ORF7 is a terminase subunit, and ORF7 harbors a zinc-finger motif, which is conserved among other herpesviral terminases. However, the biological significance of ORF7 is unknown. We previously reported that KSHV ORF17 is essential for the cleavage of inner scaffold proteins in capsid maturation, and ORF17 knockout (KO) induced capsid formation arrest between the procapsid and B-capsid stages. However, it remains unknown if ORF7-mediated viral DNA cleavage occurs before or after ORF17-mediated scaffold collapse. We analyzed the role of ORF7 during capsid formation using ORF7-KO-, ORF7&17-double-KO (DKO)-, and ORF7-zinc-finger motif mutant-KSHVs. We found that ORF7 acted after ORF17 in the capsid formation process, and ORF7-KO-KSHV produced incomplete capsids harboring non-spherical internal structures, which resembled soccer balls. This soccer ball-like capsid was formed after ORF17-mediated B-capsid formation. Moreover, ORF7-KO- and zinc-finger motif KO-KSHV failed to appropriately cleave the TR on replicated genome and had a defect in virion production. Thus, our data revealed that ORF7 contributes to terminase-mediated viral genome cleavage and capsid formation.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The contribution of Kaposi’s sarcoma-associated herpesvirus ORF7 and its zinc-finger motif to viral genome cleavage and capsid formation

Iwaisako

Watanabe

Sekine

et al. 2022

Preprint

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The viral packaging motor potentiates late gene expression in Kaposi’s sarcoma-associated herpesvirus

McCollum

Didychuk

Liu

et al. 2023

Preprint

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Beta- and gamma-herpesviruses transcribe their late genes in a manner distinct from host transcription. This process is directed by a complex of viral transcriptional activator proteins that hijack cellular RNA polymerase II and an unknown set of additional factors. We employed proximity labeling coupled with mass spectrometry, followed by CRISPR and siRNA screening to identify proteins functionally associated with the Kaposi's sarcoma-associated herpesvirus (KSHV) late gene transcriptional complex. These data revealed that the catalytic subunit of the viral DNA packaging motor, ORF29, is both dynamically associated with the viral transcriptional activator complex and potentiates late gene expression. Through genetic mutation and deletion of ORF29, we establish that its catalytic activity potentiates viral transcription and is required for robust accumulation of essential late proteins during infection. Thus, we propose an expanded role for ORF29 that encompasses its established function in viral packaging and its newly discovered contributions to viral transcription and late gene expression in KSHV.

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Kaposi’s sarcoma-associated herpesvirus ORF67.5 functions as a component of the terminase complex

Iwaisako

Watanabe

Suzuki

et al. 2023

Preprint

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Kaposi’s sarcoma-associated herpesvirus (KSHV) is a double-stranded DNA gammaherpesvirus, with a poorly characterized lytic replication cycle. However, the lytic replication cycle of the alpha- and betaherpesviruses are well characterized. During lytic infection of alpha- and betaherpesviruses, the viral genome is replicated as a precursor form, which contains tandem genomes linked via terminal repeats (TRs). One genomic unit of the precursor form is packaged into a capsid and is cleaved at the TR by the terminase complex. While the alpha- and betaherpesvirus terminases are well characterized, the KSHV terminase remains poorly understood. KSHV ORF7, ORF29, and ORF67.5 are presumed to be components of the terminase complex based on their homology to other terminase proteins. We previously reported that ORF7-deficient KSHV formed numerous immature soccer ball-like capsids and failed to cleave the TRs. ORF7 interacted with ORF29 and ORF67.5, however ORF29 and ORF67.5 did not interact with each other. While these results suggested that ORF7 is important for KSHV terminase function and capsid formation, the function of ORF67.5 was completely unknown. Therefore, to analyze the function of ORF67.5, we constructed ORF67.5-deficient BAC16. ORF67.5-deficient KSHV failed to produce infectious virus, failed to cleave the TRs, and numerous soccer ball-like capsids were observed in ORF67.5-deficient KSHV-harboring cells. Furthermore, ORF67.5 promoted the interaction between ORF7 and ORF29, and ORF29 increased the interaction between ORF67.5 and ORF7. Thus, our data indicated that ORF67.5 functions as a component of the KSHV terminase complex by contributing to TR cleavage, terminase complex formation, capsid formation, and virus production.

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Kaposi’s Sarcoma-Associated Herpesvirus ORF7 Is Essential for Virus Production

Cited by 9 publications

References 37 publications

The contribution of Kaposi’s sarcoma-associated herpesvirus ORF7 and its zinc-finger motif to viral genome cleavage and capsid formation

The contribution of Kaposi’s sarcoma-associated herpesvirus ORF7 and its zinc-finger motif to viral genome cleavage and capsid formation

The viral packaging motor potentiates late gene expression in Kaposi’s sarcoma-associated herpesvirus

Kaposi’s sarcoma-associated herpesvirus ORF67.5 functions as a component of the terminase complex

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