LEUNIG (LUG) is an Arabidopsis thaliana transcriptional co-repressor that regulates the floral homeotic gene AGAMOUS (Connor et al., 2000). It is a member of the GroTLE family of transcriptional co-repressors, which do not possess DNA binding motifs but repress a diverse number of target genes through targeted recruitment by site-specific DNA binding transcription factors. Groucho (Gro), which was discovered in Drosophila melanogaster, is the founding member of the highly conserved Gro family of transcriptional corepressors with WD repeats and Q-rich domains (Jennings et al., 2008). Gro family members target specific promoters by interacting with DNA binding transcription factors or other cofactors and they repress transcription by recruiting either HDAC or mediator complexes (Lee et al., 2015).
In Arabidopsis, the 13 members of the Gro family are divided into the LEUNIG (LUG) and TOPLESS (TPL) subclades, but both subclades act as transcriptional corepressors to regulate plant development and hormonal signaling. At LUENIG (LUG) accomplishes binding to site specific DNA binding transcription factors by using an adaptor protein, SEUSS (SEU) (Grigorova et al., 2011). These corepressors affect this repression by interaction with Arabidopsis Mediator components AtMED19/SWP and AtCDK8/HEN3, as well as interaction with histone de-acetylase 19 (HDA19) (Gonzalez et al., 2007). LUG binds DNA indirectly via transcription factors like APETALA1 (AP1), SEPALLATA3 (SEP3), SHORT VEGETATIVE PHASE (SVP), AGL24, and YABBY to repress targets like AG (Lee et al., 2015). The two transcriptional regulators, SEEDSTICK (STK) and LEUNIG-HOMOLOG (LUH), positively regulate seed growth. These factors regulate specific aspects of cell wall properties such as pectin distribution (Di Marzo et al., 2022).
In rice, the floral organ gene KAIKOUXIAO (KKX), mutation produces an uncharacteristic open hull, abnormal seed and semi-sterility. KKX encodes a putative LEUNIG-like (LUGL) transcriptional regulator OsLUGL. A OsLUGL-OsSEU-OsAP1-OsSEP3 complex acts as a transcriptional co-regulator by targeting the promoter of OsGH3-8, then affecting auxin level, OsARFs expression and thereby influencing floral development (Yang et al., 2019).
Last updated June 2023 by John Gray
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