The plant RNA polymerase II elongation complex: A hub coordinating transcript elongation and mRNA processing

Abstract

Characterisation of the Arabidopsis RNA polymerase II (RNAPII) elongation complex revealed an assembly of a conserved set of transcript elongation factors associated with chromatin remodellers, histone modifiers as well as with various pre-mRNA splicing and polyadenylation factors. Therefore, transcribing RNAPII streamlines the processes of mRNA synthesis and processing in plants.

Keywords: RNA polymerase II; chromatin; polyadenylation; splicing; transcript elongation.

Figure 1.

Scheme depicting the Arabidopsis RNAPII elongation complex based on affinity purification of TEFs in combination with mass spectrometry analyses. The TEFs FACT, TFIIS, SPT4/SPT5, SPT6, SPT6L and PAF1-C (dark blue) robustly co-purified with each other and with RNAPII (red), while P-TEFb (light blue) was not enriched in these experiments. Moreover, further chromatin factors (yellow) also repeatedly co-purified with the TEFs, except for SWR1/NuA4 (orange), which was primarily isolated along with P-TEFb. In addition to the transcription related proteins, many spliceosomal components (dark grey) and polyadenylation factors (light grey) co-purified with the TEFs.

Figure 2.

tfIIs elf7 double-mutant Arabidopsis plants in comparison to the respective single-mutants and the Col-0 wild type. While tfIIs has essentially wild type appearance and elf7 is relatively mildly affected, the growth of tfIIs elf7 double-mutant plants is severely reduced, which is obvious from the rosette diameter. Plants at 28 days after stratification grown under long-day conditions are shown.