The RNA binding specificity of Spt4/5 provides insight into the control of transcription elongation. — University of Technology
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The RNA binding specificity of Spt4/5 provides insight into the control of transcription elongation. (14271)

Amanda Blythe 1 , Berra Yazar-Klosinski 2 , Michael W Webster 3 , Eefi Chen 2 , Marylene Vandevenne 3 , Katerina Bendak 3 , Joel P Mackay 3 , Grant A Hartzog 2 , Alice Vrielink 1
  1. University of Western Australia, Crawley, WA, Australia
  2. Molecular, Cell and Developmental Biology, University of California, Santa Cruz, California, United States of America
  3. School of Molecular Bioscience, University of Sydney, Camperdown, NSW, Australia

Spt4/5 is an essential and ancient regulator of transcription elongation.  The heterodimeric transcription elongation factor can both inhibit and promote the processivity of RNAPII during transcription elongation; however, the mechanism underlying these roles remains elusive.  The zinc-finger protein Spt4 and the N-terminal domain of Spt5 has been shown to bind in the middle of the RNAPII claw, acting to completely encircle the DNA in the binding channel during transcription 12.   The region of Spt5 C-terminal to its Spt4 binding domain has five proposed RNA-binding (KOW domains).  It has been hypothesised that the first KOW domain of Spt5 stabilises the upstream DNA as it emerges from the transcription bubble, and the second to fifth KOW domains contact the nascent RNA as it emerges from RNAPII1 . 

Using nucleic-acid binding assays and biophysical techniques we have explored the RNA binding specificity of the Saccharomyces cerevisiae Spt4/5 and have discovered sequence specific RNA motifs validated through genomic analysis.  These data provide insight into the RNA binding mechanism of the protein, and raises provocative questions regarding the mechanism underlying transcription elongation. 

  1. Klein, B. J., Bose, D., Baker, K. J., Yusoff, Z. M., Zhang, X., and Murakami, K. S. (2011) RNA polymerase and transcription elongation factor Spt4/5 complex structure, Proceedings of the National Academy of Sciences 108, 546.
  2. Martinez-Rucobo, F. W., Sainsbury, S., Cheung, A. C. M., and Cramer, P. (2011) Architecture of the RNA polymerase-Spt4/5 complex and basis of universal transcription processivity, EMBO J. 30, 1302-1310
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