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. 1993 Jan 1;90(1):168–172. doi: 10.1073/pnas.90.1.168

The role of zinc fingers in transcriptional activation by transcription factor IIIA.

S Del Rio 1, D R Setzer 1
PMCID: PMC45621  PMID: 8419919

Abstract

We have described elsewhere a number of the properties of a set of mutant forms of Xenopus transcription factor IIIA (TFIIIA) containing single amino acid substitutions that result in the structural disruption of individual zinc finger domains. These "broken finger" proteins have now been analyzed with respect to their ability to support transcription of 5S rRNA genes in vitro. Disruption of any one of the first six zinc fingers of TFIIIA has no discernible effect on the activity of the protein in supporting 5S rRNA synthesis in standard in vitro transcription assays, despite the fact that some of these mutant proteins exhibit large decreases in their binding affinity for 5S rRNA genes in binary complexes. These results indicate that the activity of TFIIIA as a transcription factor can be largely independent of its equilibrium binding constant for the 5S rRNA gene in the absence of other components of the RNA polymerase III transcriptional apparatus. In fact, this finding is consistent with the known pathway and kinetics of assembly of 5S rRNA transcription complexes. In contrast to the results obtained with finger 1-6 mutants, analogous mutations in zinc fingers 7-9 of TFIIIA result in moderate to complete loss of transcriptional activity. We interpret these results to mean that the three C-terminal zinc fingers of TFIIIA are not only involved in binding to the internal control region of 5S rRNA genes but are also required, either directly or indirectly, for higher-order interactions that are important in transcription complex assembly, stability, or activity.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bieker J. J., Martin P. L., Roeder R. G. Formation of a rate-limiting intermediate in 5S RNA gene transcription. Cell. 1985 Jan;40(1):119–127. doi: 10.1016/0092-8674(85)90315-0. [DOI] [PubMed] [Google Scholar]
  2. Bogenhagen D. F., Wormington W. M., Brown D. D. Stable transcription complexes of Xenopus 5S RNA genes: a means to maintain the differentiated state. Cell. 1982 Feb;28(2):413–421. doi: 10.1016/0092-8674(82)90359-2. [DOI] [PubMed] [Google Scholar]
  3. Brent R., Ptashne M. A eukaryotic transcriptional activator bearing the DNA specificity of a prokaryotic repressor. Cell. 1985 Dec;43(3 Pt 2):729–736. doi: 10.1016/0092-8674(85)90246-6. [DOI] [PubMed] [Google Scholar]
  4. Del Río S., Setzer D. R. High yield purification of active transcription factor IIIA expressed in E. coli. Nucleic Acids Res. 1991 Nov 25;19(22):6197–6203. doi: 10.1093/nar/19.22.6197. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Diakun G. P., Fairall L., Klug A. EXAFS study of the zinc-binding sites in the protein transcription factor IIIA. Nature. 1986 Dec 18;324(6098):698–699. doi: 10.1038/324698a0. [DOI] [PubMed] [Google Scholar]
  6. Dignam J. D., Martin P. L., Shastry B. S., Roeder R. G. Eukaryotic gene transcription with purified components. Methods Enzymol. 1983;101:582–598. doi: 10.1016/0076-6879(83)01039-3. [DOI] [PubMed] [Google Scholar]
  7. Jantzen H. M., Admon A., Bell S. P., Tjian R. Nucleolar transcription factor hUBF contains a DNA-binding motif with homology to HMG proteins. Nature. 1990 Apr 26;344(6269):830–836. doi: 10.1038/344830a0. [DOI] [PubMed] [Google Scholar]
  8. Lassar A. B., Martin P. L., Roeder R. G. Transcription of class III genes: formation of preinitiation complexes. Science. 1983 Nov 18;222(4625):740–748. doi: 10.1126/science.6356356. [DOI] [PubMed] [Google Scholar]
  9. Miller J., McLachlan A. D., Klug A. Repetitive zinc-binding domains in the protein transcription factor IIIA from Xenopus oocytes. EMBO J. 1985 Jun;4(6):1609–1614. doi: 10.1002/j.1460-2075.1985.tb03825.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Setzer D. R., Brown D. D. Formation and stability of the 5 S RNA transcription complex. J Biol Chem. 1985 Feb 25;260(4):2483–2492. [PubMed] [Google Scholar]
  11. Smith D. R., Jackson I. J., Brown D. D. Domains of the positive transcription factor specific for the Xenopus 5S RNA gene. Cell. 1984 Jun;37(2):645–652. doi: 10.1016/0092-8674(84)90396-9. [DOI] [PubMed] [Google Scholar]
  12. Young L. S., Dunstan H. M., Witte P. R., Smith T. P., Ottonello S., Sprague K. U. A class III transcription factor composed of RNA. Science. 1991 Apr 26;252(5005):542–546. doi: 10.1126/science.1708526. [DOI] [PubMed] [Google Scholar]

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