Sun Woo Honga,b
, Seong Min Honga
, Jae Wook Yooa,b
, Young Chul Leec
, Soyoun Kimd
, John T. Lise
and Dong-ki Leea,b,1
aGlobal Research Laboratory for RNAi Medicine,
bBK21 School of Chemical Materials Science and Department of Chemistry, Sungkyunkwan University, Suwon 440-746, Korea;
cHormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, Korea;
dDepartment of Biomedical Engineering, Dongguk University, Seoul 100-715, Korea; and
eDepartment of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
Ser-5 phosphorylation of the RNA polymerase II (Pol II) C-terminal domain by TFIIH kinase has been implicated in critical steps in mRNA synthesis, such as Pol II promoter escape and mRNA 5′-capping. However, the general requirement and precise role of TFIIH kinase in Pol II transcription still remain elusive. Here we use a chemical genetics approach to show that, for a majority of budding-yeast genes, specific inhibition of the yeast TFIIH kinase results in a dramatic reduction in both mRNA level and Ser-5 C-terminal domain phosphorylation. Surprisingly, inhibition of TFIIH kinase activity only partially affected both Pol II density and Ser-2 phosphorylation level. The discrepancy between mRNA level and Pol II density is attributed to the defective 5′-capping, which results in the destabilization of mRNAs. Therefore, contrary to the current belief, our study points strongly toward a minor role of TFIIH kinase in Pol II transcription, and a more significant role in mRNA capping in budding yeast.
chemical genetics, Kin28, mRNA capping
1To whom correspondence should be addressed.
Author contributions: S.W.H., J.T.L., and D.-k.L. designed research; S.W.H., S.M.H., and J.W.Y. performed research; Y.C.L. and S.K. contributed new reagents/analytic tools; S.W.H., S.M.H., J.W.Y., J.T.L., and D.-k.L. analyzed data; and S.W.H., J.T.L., and D.-k.L. wrote the paper.
Edited by Jeffrey W. Roberts, Cornell University, Ithaca, NY, and approved July 7, 2009
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.