TAP Family: BES1
Yin et al (2005): Brassinosteroids (BRs) signal through a plasma membrane-localized receptor kinase to regulate plant growth and development. We showed previously that a novel protein, BES1, accumulates in the nucleus in response to BRs, where it plays a role in BR-regulated gene expression; however, the mechanism by which BES1 regulates gene expression is unknown. In this study, we dissect BES1 subdomains and establish that BES1 is a transcription factor that binds to and activates BR target gene promoters both in vitro and in vivo. BES1 interacts with a basic helix-loop-helix protein, BIM1, to synergistically bind to E box (CANNTG) sequences present in many BR-induced promoters. Loss-of-function and gain-of-function mutants of BIM1 and its close family members display BR response phenotypes. Thus, BES1 defines a new class of plant-specific transcription factors that cooperate with transcription factors such as BIM1 to regulate BR-induced genes.
This TAP family belongs to the Basic helix-loop-helix factors (bHLH) structural class of the Basic domains structural superclass, as defined in Plant-TFClass (Blanc-Mathieu et al. 2024)
References:
Li, L; Deng, XW. 2005. It runs in the family: regulation of brassinosteroid signaling by the BZR1-BES1 class of transcription factors. Trends Plant Sci. 10(6):266-8
Vert, G; Nemhauser, JL; Geldner, N; Hong, F; Chory, J. 2005. Molecular mechanisms of steroid hormone signaling in plants. Annu. Rev. Cell Dev. Biol. 21:177-201"
Yin, Y; Vafeados, D; Tao, Y; Yoshida, S; Asami, T; Chory, J. 2005. A new class of transcription factors mediates brassinosteroid-regulated gene expression in Arabidopsis. Cell 120(2):249-59"
Blanc-Mathieu, Romain et al. 2024. Plant-TFClass: a structural classification for plant transcription factors. Trends in Plant Science, Volume 29, Issue 1, 40 - 51
