Functional characterization and evolutionary history of plant PRC1 RING finger protein homologs

• Applicant: Professor Dr. Marcus Koch
• Subject Area: Evolution and Systematics of Plants and Fungi
• Term: from 2007 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 43680316

The Polycomb group (PcG) encodes a set of chromatin-modifying proteins conserved during evolution that maintains stably inherited repression of target genes. In Drosophila and vertebrates, the repression of the target genes is controlled by the cooperation of two PcG complexes: Polycomb repressive complex (PRC)2 that labels the targets by adding histone methyl marks, and PRC1 that works as an “effector” of transcriptional repression. In Arabidopsis, three PRC2 equivalents have been hypothesized based on subunit composition and protein function; however, homologs of PRC1 components have not been identified in plants, opening the possibility that plants employ alternative mechanisms from that of animals to maintain the transcriptional repression. Surprisingly, our recent database search revealed the presence of putative homologs of some of the PRC1 components in Arabidopsis and rice genomes. The conserved domain architecture among these proteins favours the functional conservation of PRC1 in higher plant. Since PcG-mediated silencing mechanism plays an essential role in eukaryotic gene regulation, changes in the mechanism that control gene regulation may be fundamentally important for interspecific differentiation. Therefore, a better understanding of the mechanism that control gene regulation is central for developmental and evolutionary biology. In this proposal, using biochemical and genetic approaches we will investigate whether these plant PRC1 protein homologs are functionally conserved to their animal counterparts or if they play a different role in these organisms. In addition, using a comparative genomics approach we will study the evolutionary history of these important developmental genes in plants. The fusion of the two approaches will provide a key to understand the evolution of the PcG silencing mechanism.

• DFG Programme: Research Grants