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Iwaisako Y, Watanabe T, Futo M, Okabe R, Sekine Y, Suzuki Y, Nakano T, Fujimuro M. The Contribution of Kaposi's Sarcoma-Associated Herpesvirus ORF7 and Its Zinc-Finger Motif to Viral Genome Cleavage and Capsid Formation. J Virol 2022;:e0068422. [PMID: 36073924 DOI: 10.1128/jvi.00684-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During Kaposi’s sarcoma-associated herpesvirus (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 alpha- and betaherpesviruses 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 nonspherical 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. Interestingly, ORF17 function was also necessary for TR cleavage. Thus, our data revealed ORF7 contributes to terminase-mediated viral genome cleavage and capsid formation. IMPORTANCE In herpesviral capsid formation, the viral terminase complex cleaves the TR sites on newly synthesized tandemly repeating genomes and inserts an appropriate genomic unit into an immature capsid. Herpes simplex virus 1 (HSV-1) UL28 is a subunit of the terminase complex that cleaves the replicated viral genome. However, the physiological importance of the UL28 homolog, KSHV ORF7, remains poorly understood. Here, using several ORF7-deficient KSHVs, we found that ORF7 acted after ORF17-mediated scaffold collapse in the capsid maturation process. Moreover, ORF7 and its zinc-finger motif were essential for both cleavage of TR sites on the KSHV genome and virus production. ORF7-deficient KSHVs produced incomplete capsids that resembled a soccer ball. To our knowledge, this is the first report showing ORF7-KO-induced soccer ball-like capsids production and ORF7 function in the KSHV capsid assembly process. Our findings provide insights into the role of ORF7 in KSHV capsid formation.
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Lai T, Wang X, Ye B, Jin M, Chen W, Wang Y, Zhou Y, Blanks AM, Gu M, Zhang P, Zhang X, Li C, Wang H, Liu Y, Gallusci P, Tör M, Hong Y. Molecular and functional characterization of the SBP-box transcription factor SPL-CNR in tomato fruit ripening and cell death. J Exp Bot 2020; 71:2995-3011. [PMID: 32016417 PMCID: PMC7260717 DOI: 10.1093/jxb/eraa067] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 02/01/2020] [Indexed: 05/19/2023]
Abstract
SlSPL-CNR, an SBP-box transcription factor (TF) gene residing at the epimutant Colourless non-ripening (Cnr) locus, is involved in tomato ripening. This epimutant provides a unique model to investigate the (epi)genetic basis of fruit ripening. Here we report that SlSPL-CNR is a nucleus-localized protein with a distinct monopartite nuclear localization signal (NLS). It consists of four consecutive residues ' 30KRKR33' at the N-terminus of the protein. Mutation of the NLS abolishes SlSPL-CNR's ability to localize in the nucleus. SlSPL-CNR comprises two zinc-finger motifs (ZFMs) within the C-terminal SBP-box domain. Both ZFMs contribute to zinc-binding activity. SlSPL-CNR can induce cell death in tomato and tobacco, dependent on its nuclear localization. However, the two ZFMs have differential impacts on SlSPL-CNR's induction of severe necrosis or mild necrotic ringspot. NLS and ZFM mutants cannot complement Cnr fruits to ripen. SlSPL-CNR interacts with SlSnRK1. Virus-induced SlSnRK1 silencing leads to reduction in expression of ripening-related genes and inhibits ripening in tomato. We conclude that SlSPL-CNR is a multifunctional protein that consists of a distinct monopartite NLS, binds to zinc, and interacts with SlSnRK1 to affect cell death and tomato fruit ripening.
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Affiliation(s)
- Tongfei Lai
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Xiaohong Wang
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Bishun Ye
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Mingfei Jin
- School of Life Sciences, East China Normal University, Shanghai, China
- Warwick-Hangzhou Joint RNA Signaling Laboratory, School of Life Sciences, University of Warwick, Coventry, UK
| | - Weiwei Chen
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Ying Wang
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Yingying Zhou
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Andrew M Blanks
- Cell and Developmental Biology, Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Mei Gu
- The Gurdon Institute, University of Cambridge, Cambridge, UK
| | - Pengcheng Zhang
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Xinlian Zhang
- Department of Family Medicine and Public Health, Division of Biostatistics & Bioinformatics, University of California San Diego, La Jolla, CA, USA
| | - Chunyang Li
- Warwick-Hangzhou Joint RNA Signaling Laboratory, School of Life Sciences, University of Warwick, Coventry, UK
| | - Huizhong Wang
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Yule Liu
- MOE Key Laboratory of Bioinformatics, Centre for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Philippe Gallusci
- Laboratory of Grape Ecophysiology and Functional Biology, Bordeaux University, INRA, Bordeaux Science Agro, Villenave d’Ornon, France
| | - Mahmut Tör
- Worcester-Hangzhou Joint Molecular Plant Health Laboratory, School of Science and the Environment, University of Worcester, Worcester, UK
| | - Yiguo Hong
- Research Centre for Plant RNA Signaling and Zhejiang Provincial Key Laboratory for Genetic Improvement and Quality Control of Medicinal Plants, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
- Warwick-Hangzhou Joint RNA Signaling Laboratory, School of Life Sciences, University of Warwick, Coventry, UK
- Worcester-Hangzhou Joint Molecular Plant Health Laboratory, School of Science and the Environment, University of Worcester, Worcester, UK
- Correspondence: , or
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Luo L, Ando S, Sakamoto Y, Suzuki T, Takahashi H, Ishibashi N, Kojima S, Kurihara D, Higashiyama T, Yamamoto KT, Matsunaga S, Machida C, Sasabe M, Machida Y. The formation of perinucleolar bodies is important for normal leaf development and requires the zinc-finger DNA-binding motif in Arabidopsis ASYMMETRIC LEAVES2. Plant J 2020; 101:1118-1134. [PMID: 31639235 PMCID: PMC7155070 DOI: 10.1111/tpj.14579] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 09/30/2019] [Accepted: 10/08/2019] [Indexed: 05/27/2023]
Abstract
In Arabidopsis, the ASYMMETRIC LEAVES2 (AS2) protein plays a key role in the formation of flat symmetric leaves via direct repression of the abaxial gene ETT/ARF3. AS2 encodes a plant-specific nuclear protein that contains the AS2/LOB domain, which includes a zinc-finger (ZF) motif that is conserved in the AS2/LOB family. We have shown that AS2 binds to the coding DNA of ETT/ARF3, which requires the ZF motif. AS2 is co-localized with AS1 in perinucleolar bodies (AS2 bodies). To identify the amino acid signals in AS2 required for formation of AS2 bodies and function(s) in leaf formation, we constructed recombinant DNAs that encoded mutant AS2 proteins fused to yellow fluorescent protein. We examined the subcellular localization of these proteins in cells of cotyledons and leaf primordia of transgenic plants and cultured cells. The amino acid signals essential for formation of AS2 bodies were located within and adjacent to the ZF motif. Mutant AS2 that failed to form AS2 bodies also failed to rescue the as2-1 mutation. Our results suggest the importance of the formation of AS2 bodies and the nature of interactions of AS2 with its target DNA and nucleolar factors including NUCLEOLIN1. The partial overlap of AS2 bodies with perinucleolar chromocenters with condensed ribosomal RNA genes implies a correlation between AS2 bodies and the chromatin state. Patterns of AS2 bodies in cells during interphase and mitosis in leaf primordia were distinct from those in cultured cells, suggesting that the formation and distribution of AS2 bodies are developmentally modulated in plants.
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Affiliation(s)
- Lilan Luo
- Division of Biological ScienceGraduate School of ScienceNagoya UniversityNagoyaAichi464‐8602Japan
- Present address:
Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijing100101China
| | - Sayuri Ando
- Graduate School of Bioscience and BiotechnologyChubu UniversityKasugaiAichi487‐8501Japan
| | - Yuki Sakamoto
- Department of Applied Biological ScienceFaculty of Science and TechnologyTokyo University of ScienceNodaChiba278‐8510Japan
- Department of Biological SciencesGraduate School of ScienceOsaka University1‐1 Machikaneyama‐choToyonakaOsaka560‐0043Japan
| | - Takanori Suzuki
- Division of Biological ScienceGraduate School of ScienceNagoya UniversityNagoyaAichi464‐8602Japan
- Central Research InstituteIshihara Sangyo Kaisha, Ltd.2‐3‐1 Nishi‐ShibukawaKusatsuShiga525‐0025Japan
| | - Hiro Takahashi
- Graduate School of Medical SciencesKanazawa UniversityKakuma‐machiKanazawaIshikawa920‐1192Japan
| | - Nanako Ishibashi
- Division of Biological ScienceGraduate School of ScienceNagoya UniversityNagoyaAichi464‐8602Japan
| | - Shoko Kojima
- Graduate School of Bioscience and BiotechnologyChubu UniversityKasugaiAichi487‐8501Japan
| | - Daisuke Kurihara
- JST, PRESTOFuro‐cho, Chikusa‐kuNagoyaAichi464‐8601Japan
- Institute of Transformative Bio‐Molecules (ITbM)Nagoya UniversityFuro‐cho, Chiku00sa‐kuNagoyaAichi464‐8601Japan
| | - Tetsuya Higashiyama
- Division of Biological ScienceGraduate School of ScienceNagoya UniversityNagoyaAichi464‐8602Japan
- Institute of Transformative Bio‐Molecules (ITbM)Nagoya UniversityFuro‐cho, Chiku00sa‐kuNagoyaAichi464‐8601Japan
- Department of Biological SciencesGraduate School of ScienceUniversity of Tokyo7‐3‐1 Hongo, Bukyo‐kuTokyo113‐0033Japan
| | - Kotaro T. Yamamoto
- Division of Biological SciencesFaculty of ScienceHokkaido UniversitySapporo060‐0810Japan
| | - Sachihiro Matsunaga
- Department of Applied Biological ScienceFaculty of Science and TechnologyTokyo University of ScienceNodaChiba278‐8510Japan
| | - Chiyoko Machida
- Graduate School of Bioscience and BiotechnologyChubu UniversityKasugaiAichi487‐8501Japan
| | - Michiko Sasabe
- Department of BiologyFaculty of Agriculture and Life ScienceHirosaki University3 Bunkyo‐choHirosaki036‐8561Japan
| | - Yasunori Machida
- Division of Biological ScienceGraduate School of ScienceNagoya UniversityNagoyaAichi464‐8602Japan
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Fukuzawa H, Miura K, Ishizaki K, Kucho KI, Saito T, Kohinata T, Ohyama K. Ccm1, a regulatory gene controlling the induction of a carbon-concentrating mechanism in Chlamydomonas reinhardtii by sensing CO2 availability. Proc Natl Acad Sci U S A 2001; 98:5347-52. [PMID: 11287669 PMCID: PMC33212 DOI: 10.1073/pnas.081593498] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Aquatic photosynthetic organisms, including the green alga Chlamydomonas reinhardtii, induce a set of genes for a carbon-concentrating mechanism (CCM) to acclimate to CO2-limiting conditions. This acclimation is modulated by some mechanisms in the cell to sense CO2 availability. Previously, a high-CO2-requiring mutant C16 defective in an induction of the CCM was isolated from C. reinhardtii by gene tagging. By using this pleiotropic mutant, we isolated a nuclear regulatory gene, Ccm1, encoding a 699-aa hydrophilic protein with a putative zinc-finger motif in its N-terminal region and a Gln repeat characteristic of transcriptional activators. Introduction of Ccm1 into this mutant restored an active carbon transport through the CCM, development of a pyrenoid structure in the chloroplast, and induction of a set of CCM-related genes. That a 5,128-base Ccm1 transcript and also the translation product of 76 kDa were detected in both high- and low-CO2 conditions suggests that CCM1 might be modified posttranslationally. These data indicate that Ccm1 is essential to control the induction of CCM by sensing CO2 availability in Chlamydomonas cells. In addition, complementation assay and identification of the mutation site of another pleiotropic mutant, cia5, revealed that His-54 within the putative zinc-finger motif of the CCM1 is crucial to its regulatory function.
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Affiliation(s)
- H Fukuzawa
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
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