卡波西氏肉瘤相关疱疹病毒ORF61蛋白在丝状聚集物中分离APOBEC3B。

IF 3.8 2区 医学 Q2 VIROLOGY
Journal of Virology Pub Date : 2025-07-22 Epub Date: 2025-06-05 DOI:10.1128/jvi.00789-25
Laura-Marie Luoto, Enrico Caragliano, Carola Schneider, Rudolph Reimer, Wolfram Brune
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引用次数: 0

摘要

疱疹病毒是一种编码细胞酶同源物的大型DNA病毒。病毒核糖核苷酸还原酶由大的R1亚基和小的R2亚基组成,是合成脱氧核糖核苷酸所必需的。然而,疱疹病毒已经重新利用R1亚基在病毒-宿主相互作用和免疫逃避中发挥额外的非规范功能。本研究研究了卡波西肉瘤相关疱疹病毒(KSHV)和鼠γ疱疹病毒68 (MHV-68)的R1蛋白,这两种γ-疱疹病毒属于rhadinvirus属。我们发现orf61编码的病毒R1蛋白在感染细胞中形成细长的细胞质凝聚体,其结构不同于先前描述的其他疱疹病毒的R1凝聚体。荧光标记的ORF61凝聚物表现出固体聚集体的性质,这是通过光漂白后的荧光恢复(FRAP)来确定的。相关光镜和电镜(CLEM)显示ORF61聚集体由丝状束组成。KSHV ORF61蛋白与感染细胞中的胞嘧啶脱氨酶APOBEC3B相互作用,并将其从细胞核(病毒DNA复制的部位)转移到细胞质聚体中。APOBEC3B的聚集形成和重新定位依赖于ORF61 c端一个保守的诱导蛋白聚集基序(IPAM)。KSHV ORF61 IPAM突变体易受apobec3b介导的脱质和复制降低滴度。相比之下,MHV-68 ORF61没有重新定位人类或小鼠的APOBEC3蛋白,这表明它参与不同的靶蛋白。结果表明,放射状病毒ORF61蛋白在感染细胞中形成细长的丝状聚体,以隔离和灭活靶蛋白,如APOBEC3B。疱疹病毒是一种大型DNA病毒,其编码的酶与宿主细胞中的酶相似。它们的核糖核苷酸还原酶的R1亚基对DNA合成很重要,并在免疫逃避和病毒-宿主相互作用中起额外的作用。本文研究了两种γ-疱疹病毒的R1蛋白ORF61。与其他疱疹病毒的同源物不同,KSHV和mhv - 68r1蛋白在感染细胞中形成由丝状束组成的细胞质聚集体。KSHV ORF61从细胞核(病毒DNA复制位点)耗尽致突变细胞酶APOBEC3B,并将其隔离在细胞质聚物中,从而保护病毒基因组免受APOBEC3B介导的突变的影响。这一过程依赖于ORF61中一个特定的保守基序。然而,MHV-68 ORF61蛋白不会重新分配APOBEC3蛋白,这表明它结合了不同的靶点。这些发现揭示了放射状病毒如何利用丝状ORF61聚集体操纵宿主抗病毒防御。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Kaposi's sarcoma-associated herpesvirus ORF61 protein sequesters APOBEC3B in filamentous aggregates.

Herpesviruses are large DNA viruses that encode homologs of cellular enzymes. The viral ribonucleotide reductase, which consists of large R1 and small R2 subunits, is required for deoxyribonucleotide synthesis. However, herpesviruses have repurposed the R1 subunit for additional non-canonical functions in virus-host interaction and immune evasion. Here, we investigated the R1 proteins of Kaposi's sarcoma-associated herpesvirus (KSHV) and murine gammaherpesvirus 68 (MHV-68), two γ-herpesviruses of the genus Rhadinovirus. We show that the ORF61-encoded viral R1 proteins form elongated cytoplasmic condensates in infected cells, which structurally differ from the previously described R1 condensates of other herpesviruses. Fluorescently labeled ORF61 condensates exhibited the properties of solid aggregates, as determined by fluorescence recovery after photobleaching (FRAP). Correlative light and electron microscopy (CLEM) showed that ORF61 aggregates consist of filamentous bundles. The KSHV ORF61 protein interacted with the cellular cytosine deaminase APOBEC3B in infected cells and translocated it from the nucleus, the site of viral DNA replication, to the cytoplasmic aggregates. Aggregate formation and relocalization of APOBEC3B depended on a conserved Induced Protein Aggregation Motif (IPAM) in the C-terminal part of ORF61. A KSHV ORF61 IPAM mutant was vulnerable to APOBEC3B-mediated deamination and replicated to reduced titers. In contrast, MHV-68 ORF61 did not relocalize human or murine APOBEC3 proteins, suggesting that it engages different target proteins. The results show that rhadinovirus ORF61 proteins form elongated filamentous aggregates in infected cells to sequester and inactivate target proteins, such as APOBEC3B.IMPORTANCEHerpesviruses are large DNA viruses that encode enzymes similar to those in host cells. The R1 subunit of their ribonucleotide reductase is important for DNA synthesis and plays additional roles in immune evasion and virus-host interactions. This study focused on the R1 protein ORF61 of two γ-herpesviruses of the genus Rhadinovirus: KSHV and MHV-68. Unlike their homologs in other herpesviruses, KSHV and MHV-68 R1 proteins form cytoplasmic aggregates consisting of filamentous bundles in infected cells. KSHV ORF61 depletes the mutagenic cellular enzyme APOBEC3B from the nucleus, the site of viral DNA replication, and sequesters it in cytoplasmic aggregates, thereby protecting the viral genome from APOBEC3B-mediated mutations. This process relies on a specific conserved motif in ORF61. However, the MHV-68 ORF61 protein does not redistribute APOBEC3 proteins, suggesting that it binds different targets. These findings reveal how rhadinoviruses use filamentous ORF61 aggregates to manipulate host antiviral defenses.

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来源期刊
Journal of Virology
Journal of Virology 医学-病毒学
CiteScore
10.10
自引率
7.40%
发文量
906
审稿时长
1 months
期刊介绍: Journal of Virology (JVI) explores the nature of the viruses of animals, archaea, bacteria, fungi, plants, and protozoa. We welcome papers on virion structure and assembly, viral genome replication and regulation of gene expression, genetic diversity and evolution, virus-cell interactions, cellular responses to infection, transformation and oncogenesis, gene delivery, viral pathogenesis and immunity, and vaccines and antiviral agents.
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