The Epigenetic Faces of ULTRAPETALA1

Abstract

ULTRAPETALA1 (ULT1) is a versatile plant-exclusive protein, initially described as a trithorax group (TrxG) factor that regulates transcriptional activation and counteracts polycomb group (PcG) repressor function. As part of TrxG, ULT1 interacts with ARABIDOPSIS TRITHORAX1 (ATX1) to regulate H3K4me3 activation mark deposition. However, our recent studies indicate that ULT1 can also act independently of ATX1. Moreover, the ULT1 ability to interact with transcription factors (TFs) and PcG proteins indicates that it is a versatile protein with other roles. Therefore, in this work we revised recent information about the function of Arabidopsis ULT1 to understand the roles of ULT1 in plant development. Furthermore, we discuss the molecular mechanisms of ULT1, highlighting its epigenetic role, in which ULT1 seems to have characteristics of an epigenetic molecular switch that regulates repression and activation processes via TrxG and PcG complexes.

Uncovering gene-family founder events during major evolutionary transitions in animals, plants and fungi using GenEra

“…We found a putative ULTRAPETALA and ARABIDILLO homologs among charophyte algae, even though these gene families were previously reported as embryophyte and angiosperm TRGs, respectively (60,76). ARABIDILLO genes have been co-opted to modulate different developmental processes in plants through abscisic acid signaling (60), while ULTRAPETALA genes intectacts with the trithorax group of angiosperms to coordinate flower development through chromatin-dependent transcriptional regulation (76). If the homologs found in Klebsormidium nitens are reliable, this would suggest an early role of ULTRAPETALLA and ARABIDILLO homologs in streptophyte evolution (77).…”

“…Furthermore, the emergence of auxin canalization proteins and BRASSINAZOLE-RESISTANT genes likely contributed to the establishment of an internal communication system between cells in multicellular streptophytes through the regulation of the basic hormone-receptor systems that predate the evolution of multicellularity (75). We found a putative ULTRAPETALA and ARABIDILLO homologs among charophyte algae, even though these gene families were previously reported as embryophyte and angiosperm TRGs, respectively (60,76). ARABIDILLO genes have been co-opted to modulate different developmental processes in plants through abscisic acid signaling (60), while ULTRAPETALA genes intectacts with the trithorax group of angiosperms to coordinate flower development through chromatin-dependent transcriptional regulation (76).…”

Uncovering gene-family founder events during major evolutionary transitions in animals, plants and fungi using GenEra

“…Furthermore, the emergence of auxin canalization proteins and BRASSI-NAZOLE-RESISTANT genes likely contributed to the establishment of an internal communication system between cells in multicellular streptophytes through the regulation of the basic hormone-receptor systems that predate the evolution of multicellularity [84]. We found putative ARABIDILLO and ULTRAPETALA homologs among charophyte algae, even though these gene families were previously reported as embryophyte and angiosperm TRGs, respectively [65,85]. ARABIDILLO genes have been co-opted to modulate different developmental processes in plants through abscisic acid signaling [65], while ULTRAPETALA genes interact with the trithorax group of angiosperms to coordinate flower development through chromatin-dependent transcriptional regulation [85].…”

A Green Light to Switch on Genes: Revisiting Trithorax on Plants

“…Despite lacking an enzymatic domain in its structure, ULT1 has a positive effect on the H3K4me3 mark, apparently by stimulating ATX1 activity, a feature that has led to its description as an ATX1 co-activator [ 72 ]. The ULT1 function together with ATX1 seems to be restricted to some aerial tissues given that in roots, ULT1 acts independently of ATX1 [ 71 , 73 ].…”