Potential role of Arabidopsis PHP as an accessory subunit of the PAF1 transcriptional cofactor

Abstract

Paf1C is a transcriptional cofactor that has been implicated in various transcription-associated mechanisms spanning initiation, elongation and RNA processing, and is important for multiple aspects of development in Arabidopsis. Our recent studies suggest Arabidopsis Paf1C is crucial for proper regulation of genes within H3K27me3-enriched chromatin, and that a protein named PHP may act as an accessory subunit of Paf1C that promotes this function.

Figure 1

Immunoblot analysis of Arabidopsis Paf1C proteins in various genetic backgrounds. Antibodies generated against specific Paf1C proteins (PHP, ELF7, VIP3, VIP4, VIP5 and VIP6) were used to analyze total cell lysate from wild-type plants (Col-0 and Col:FRI) and Paf1C mutants (php-1/-2, elf7, vip3, vip4, vip5 and vip6). The asterisk in the VIP5 panel indicates an immunocrossreactive protein. Immunoreactivity for histone H3 is shown as a loading control (from Park et al.9).

Figure 2

Enrichment for H3K27me3 across genes that are upregulated (solid red, left part) or downregulated (solid green, right part) in a strong php mutant. Positional signals across the transcriptional unit were averaged for most protein coding genes. Genes that are misregulated in the Paf1C mutant vip3 are shown as a green or red dashed line. The averaged positional signal for most protein coding genes is shown as a solid black line; the 95^th percentile confidence intervals are depicted as dashed black lines (from Park et al.9).