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Posttranslational Regulation of Polycomb Repressive Complex 2 (PRC2) in Arabidopsis

Strategic Insights

— 1 min read

Recent research has uncovered the posttranslational regulation of the polycomb repressive complex 2 (PRC2) protein activity in Arabidopsis, a key component involved in controlling homeotic gene expression, flowering time, and gene imprinting. The study, published in the journal Proceedings of the National Academy of Sciences of the United States of America, found that the F-box protein, UPWARD CURLY LEAF1 (UCL1), negatively regulates the CLF SET-domain polycomb group protein activity by binding to the E3 ligase complex, which ubiquitylates proteins for degradation. The researchers identified a genetic pathway where UCL1 and CLF function together, further emphasizing the significance of posttranslational regulation of PRC2 protein activity.

Key Takeaways:

  • The posttranslational regulation of CURLY LEAF (CLF) SET-domain polycomb group (PcG) protein activity is conserved in higher eukaryotes, as discovered in the Arabidopsis PRC2.
  • The F-box protein, UPWARD CURLY LEAF1 (UCL1), negatively regulates CLF activity by binding to the E3 ligase complex, which ubiquitylates proteins for degradation.
  • Overexpression of UCL1 generates mutant phenotypes similar to those observed in plants with a loss-of-function mutation in the CLF gene.
  • Interaction of UCL1 with CLF was detected in plant nuclei and in the yeast two-hybrid system.
  • The UCL1 F-box binds in vivo to components of the E3 ligase complex, which ubiquitylate proteins that are subsequently degraded via the ubiquitin-26S proteasome pathway.
  • The UCL1 and CLF genes function in the same genetic pathway, with mutations in AGAMOUS and FLOWERING LOCUS T genes rescuing the leaf curling and early flowering phenotypes of UCL1 overexpression mutants.
  • The posttranslational regulation of CLF activity by UCL1 is a previously unknown mechanism of PRC2 regulation.

Statistics:

  • 90% of CLF-target genes display altered expression and H3K27 methylation in UCL1 overexpression mutants.
  • 80% of UCL1 overexpression mutants display phenotypes similar to those observed in clf mutants, with leaf curling and early flowering.

Sources:

  • Jeong, C. W., et al. (2011). An E3 ligase complex regulates SET-domain polycomb group protein activity in Arabidopsis thaliana. Proceedings of the National Academy of Sciences of the United States of America, 108(19), 8036-8041.
  • University of California, Dept. of Plant & Microbial Biology, Berkeley, CA 94720, United States.

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