Regulatory roles of plant TFIIH protein kinases

RNA polymerase II transcribes protein coding and several classes of regulatory RNAs in multicellular organisms. The C-terminal domain of the RNAPII largest subunit, RNAPII-CTD, carries conserved heptapeptide repeats that are phosphorylated at different residues by a protein kinase cascade in Arabidopsis. Recent studies start to reveal how phosphorylation of the RNAPII-CTD by TFIIH-associated protein kinases regulates growth and development via coordinated control of transcription, cell cycle and biogenesis of microRNAs and small silencing siRNAs.