Selective factor 1

Role of transcription factor in gene expression regulation

Selective factor 1 (also known as SL1) is a transcription factor that binds to the promoter of rDNA genes that were previously silent and recruits a preinitiation complex to which RNA polymerase I will bind to begin the transcription of ribosomal RNA (rRNA).[1][2]

Discovery of SL I

SL1 was discovered by Robert Tjian and his colleagues in 1985 when they separated a HeLa cell extract into two functional fractions.[3] One factor has RNA polymerase I activity, but no ability to initiate accurate transcription of a human rRNA template. This transcription factor, SL1, showed species specificity[4] That is, it could distinguish between the human and mouse rRNA promoter,[5] and added increasing amount of human template at the expense of the mice template.[6] Tijian and coworkers went on to show that by footprinting a partially purified polymerase 1 preparation could bind to the human rRNA promoter. In particular it causes a footprint over a region of the UCE called A site.[7] This binding is not due to polymerase I itself but to a transcription factor called upstream binding factor, UBF.

Functions

SLI functions in assembling the transcription preinitiation complex. It is also a major determinant of species-specificity in ribosomal RNA gene transcription. Research suggests that UBF and SL1 act synergistically to stimulate transcription. Recent investigation also suggests that SL1 is a target for cancer therapy.[8]

Structure

SL1 is composed of the TATA-binding protein and three TAFs.[9] It is therefore possible to inhibit SL1 activity with anti-TBP antibodies.

References

  1. ↑ Tuan JC et al. (1999). "Recruitment of TATA-binding protein-TAFI complex SL1 to the human ribosomal DNA promoter is mediated by the carboxy-terminal activation domain of upstream binding factor (UBF) and is regulated by UBF phosphorylation". journal of molecular cell biology 19 (6): 2872–9.
  2. ↑ Lewin's Genes XI. Retrieved 2014-08-10.
  3. ↑ Andreas Hochheimer and Robert Tjian1. "Genes Dev | Mobile". M.genesdev.cshlp.org. Retrieved 2014-08-10.
  4. ↑ Hempel, W.M.; Cavanaugh, A.H.; Hannan, R.D.; Taylor, L.; Rothblum, L.I. (1996). "The species-specific RNA polymerase I transcription factor SL-1 binds to upstream binding factor". Journal of molecular cell biology 16 (2): 557–563. PMC 231034. PMID 8552083.
  5. ↑ The Nucleolus. 2011-09-15. Retrieved 2014-08-10.
  6. ↑ Learned, R.M; Cordes, S; Tjian, R (1985). "Purification and characterization of a transcription factor that confers promoter specificity to human RNA polymerase I". Journal of molecular cell biology 5 (6): 1358.
  7. ↑ "Patent US5637686 - Tata-binding protein associated factor, nucleic acids - Google Patents". Google.com. Retrieved 2014-08-10.
  8. ↑ Villicaña et al. (2014). "The basal transcription machinery as a target for cancer therapy". Cancer Cell International 14 (18): 1475–2867. doi:10.1186/1475-2867-14-18.
  9. ↑ TBP-TAF Complex SL1 Directs RNA Polymerase I Pre-initiation Complex Formation and Stabilizes Upstream Binding Factor at the rDNA Promoter, Scotland: Journal of biological science, 2005, retrieved 2014-09-07

See also

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