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. 1992 Oct;4(10):1321–1331. doi: 10.1105/tpc.4.10.1321

Transactivation of geminivirus AR1 and BR1 gene expression by the viral AL2 gene product occurs at the level of transcription.

G Sunter 1, D M Bisaro 1
PMCID: PMC160218  PMID: 1446172

Abstract

Tomato golden mosaic virus is a bipartite geminivirus whose genome is divided between two circular DNA molecules. DNA A encodes functions necessary for viral DNA replication and encapsidation, whereas DNA B provides functions needed for movement in the host. Previous studies have shown that the viral AL2 gene product transactivates expression of the coat protein gene (AR1). We have investigated the role of the AL2 protein in the regulation of B component gene expression and examined the transcriptional and post-transcriptional components of this regulation. We found that AL2 protein is required for efficient expression of both the AR1 and BR1 genes, but not the BL1 gene. A comparison of steady state transcript levels and transcript levels determined by nuclear run-on analysis showed that activation of AR1 and BR1 gene expression by the AL2 protein occurs primarily at the level of transcription. These results provide an explanation for the lack of infectivity demonstrated by AL2 mutants, and suggest that the AL2 protein interacts with the cellular transcription machinery to activate the expression of rightward viral genes.

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Selected References

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  1. Berg J. M. Zinc fingers and other metal-binding domains. Elements for interactions between macromolecules. J Biol Chem. 1990 Apr 25;265(12):6513–6516. [PubMed] [Google Scholar]
  2. Boutry M., Chua N. H. A nuclear gene encoding the beta subunit of the mitochondrial ATP synthase in Nicotiana plumbaginifolia. EMBO J. 1985 Sep;4(9):2159–2165. doi: 10.1002/j.1460-2075.1985.tb03910.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Bradford M. M. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem. 1976 May 7;72:248–254. doi: 10.1016/0003-2697(76)90527-3. [DOI] [PubMed] [Google Scholar]
  4. Elmer J. S., Brand L., Sunter G., Gardiner W. E., Bisaro D. M., Rogers S. G. Genetic analysis of the tomato golden mosaic virus. II. The product of the AL1 coding sequence is required for replication. Nucleic Acids Res. 1988 Jul 25;16(14B):7043–7060. doi: 10.1093/nar/16.14.7043. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Evans R. M., Hollenberg S. M. Zinc fingers: gilt by association. Cell. 1988 Jan 15;52(1):1–3. doi: 10.1016/0092-8674(88)90522-3. [DOI] [PubMed] [Google Scholar]
  6. Flint J., Shenk T. Adenovirus E1A protein paradigm viral transactivator. Annu Rev Genet. 1989;23:141–161. doi: 10.1146/annurev.ge.23.120189.001041. [DOI] [PubMed] [Google Scholar]
  7. Frischmuth T., Zimmat G., Jeske H. The nucleotide sequence of abutilon mosaic virus reveals prokaryotic as well as eukaryotic features. Virology. 1990 Oct;178(2):461–468. doi: 10.1016/0042-6822(90)90343-p. [DOI] [PubMed] [Google Scholar]
  8. Gardiner W. E., Sunter G., Brand L., Elmer J. S., Rogers S. G., Bisaro D. M. Genetic analysis of tomato golden mosaic virus: the coat protein is not required for systemic spread or symptom development. EMBO J. 1988 Apr;7(4):899–904. doi: 10.1002/j.1460-2075.1988.tb02894.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Haley A., Zhan X., Richardson K., Head K., Morris B. Regulation of the activities of African cassava mosaic virus promoters by the AC1, AC2, and AC3 gene products. Virology. 1992 Jun;188(2):905–909. doi: 10.1016/0042-6822(92)90551-y. [DOI] [PubMed] [Google Scholar]
  10. Hamilton W. D., Bisaro D. M., Coutts R. H., Buck K. W. Demonstration of the bipartite nature of the genome of a single-stranded DNA plant virus by infection with the cloned DNA components. Nucleic Acids Res. 1983 Nov 11;11(21):7387–7396. doi: 10.1093/nar/11.21.7387. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Hamilton W. D., Stein V. E., Coutts R. H., Buck K. W. Complete nucleotide sequence of the infectious cloned DNA components of tomato golden mosaic virus: potential coding regions and regulatory sequences. EMBO J. 1984 Sep;3(9):2197–2205. doi: 10.1002/j.1460-2075.1984.tb02114.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Hanley-Bowdoin L., Elmer J. S., Rogers S. G. Expression of functional replication protein from tomato golden mosaic virus in transgenic tobacco plants. Proc Natl Acad Sci U S A. 1990 Feb;87(4):1446–1450. doi: 10.1073/pnas.87.4.1446. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Hanley-Bowdoin L., Elmer J. S., Rogers S. G. Functional expression of the leftward open reading frames of the A component of tomato golden mosaic virus in transgenic tobacco plants. Plant Cell. 1989 Nov;1(11):1057–1067. doi: 10.1105/tpc.1.11.1057. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Hayes R. J., Buck K. W. Replication of tomato golden mosaic virus DNA B in transgenic plants expressing open reading frames (ORFs) of DNA A: requirement of ORF AL2 for production of single-stranded DNA. Nucleic Acids Res. 1989 Dec 25;17(24):10213–10222. doi: 10.1093/nar/17.24.10213. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Johnson P. F., McKnight S. L. Eukaryotic transcriptional regulatory proteins. Annu Rev Biochem. 1989;58:799–839. doi: 10.1146/annurev.bi.58.070189.004055. [DOI] [PubMed] [Google Scholar]
  16. Lazarowitz S. G., Lazdins I. B. Infectivity and complete nucleotide sequence of the cloned genomic components of a bipartite squash leaf curl geminivirus with a broad host range phenotype. Virology. 1991 Jan;180(1):58–69. doi: 10.1016/0042-6822(91)90009-z. [DOI] [PubMed] [Google Scholar]
  17. MacDowell S. W., Coutts R. H., Buck K. W. Molecular characterisation of subgenomic single-stranded and double-stranded DNA forms isolated from plants infected with tomato golden mosaic virus. Nucleic Acids Res. 1986 Oct 24;14(20):7967–7984. doi: 10.1093/nar/14.20.7967. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Navot N., Pichersky E., Zeidan M., Zamir D., Czosnek H. Tomato yellow leaf curl virus: a whitefly-transmitted geminivirus with a single genomic component. Virology. 1991 Nov;185(1):151–161. doi: 10.1016/0042-6822(91)90763-2. [DOI] [PubMed] [Google Scholar]
  19. Rogers S. G., Bisaro D. M., Horsch R. B., Fraley R. T., Hoffmann N. L., Brand L., Elmer J. S., Lloyd A. M. Tomato golden mosaic virus A component DNA replicates autonomously in transgenic plants. Cell. 1986 May 23;45(4):593–600. doi: 10.1016/0092-8674(86)90291-6. [DOI] [PubMed] [Google Scholar]
  20. Saunders K., Lucy A., Stanley J. DNA forms of the geminivirus African cassava mosaic virus consistent with a rolling circle mechanism of replication. Nucleic Acids Res. 1991 May 11;19(9):2325–2330. doi: 10.1093/nar/19.9.2325. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Southern E. M. Detection of specific sequences among DNA fragments separated by gel electrophoresis. J Mol Biol. 1975 Nov 5;98(3):503–517. doi: 10.1016/s0022-2836(75)80083-0. [DOI] [PubMed] [Google Scholar]
  22. Stenger D. C., Revington G. N., Stevenson M. C., Bisaro D. M. Replicational release of geminivirus genomes from tandemly repeated copies: evidence for rolling-circle replication of a plant viral DNA. Proc Natl Acad Sci U S A. 1991 Sep 15;88(18):8029–8033. doi: 10.1073/pnas.88.18.8029. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Struhl K. Molecular mechanisms of transcriptional regulation in yeast. Annu Rev Biochem. 1989;58:1051–1077. doi: 10.1146/annurev.bi.58.070189.005155. [DOI] [PubMed] [Google Scholar]
  24. Sunter G., Bisaro D. M. Transcription map of the B genome component of tomato golden mosaic virus and comparison with A component transcripts. Virology. 1989 Dec;173(2):647–655. doi: 10.1016/0042-6822(89)90577-1. [DOI] [PubMed] [Google Scholar]
  25. Sunter G., Hartitz M. D., Hormuzdi S. G., Brough C. L., Bisaro D. M. Genetic analysis of tomato golden mosaic virus: ORF AL2 is required for coat protein accumulation while ORF AL3 is necessary for efficient DNA replication. Virology. 1990 Nov;179(1):69–77. doi: 10.1016/0042-6822(90)90275-v. [DOI] [PubMed] [Google Scholar]
  26. Takatsuji H., Mori M., Benfey P. N., Ren L., Chua N. H. Characterization of a zinc finger DNA-binding protein expressed specifically in Petunia petals and seedlings. EMBO J. 1992 Jan;11(1):241–249. doi: 10.1002/j.1460-2075.1992.tb05047.x. [DOI] [PMC free article] [PubMed] [Google Scholar]

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