TAP Family: HD-SAWADEE

The homeobox TF superfamily is defined by an occurrence of the characteristic homeodomain (HD) and can be defined as pan-eukaryotic since it is found in all eukaryotic organisms (Catarino et al., 2016; Romani et al., 2018). According to different references (e.g., (Catarino et al., 2016; Mukherjee et al., 2009; Que et al., 2018)), the HD superfamily is divided into 11 subfamilies, namely BEL, DDT, HDZ, KNOX, LD, NDX, PHD, PINTOX, PLINC, SAWADEE and WOX. Interestingly, all subfamilies evolved in the common ancestor, before terrestrialization and diversification of land plants (Catarino et al., 2016). Furthermore, the broad distribution and high conservation of domains induces a common highly conserved functional role in plants and whenever members are present, also in algae (Mukherjee et al., 2009). In general, homeobox TFs show diverse functions in developmental and physiological mechanisms (Romani et al., 2018). In members of the SAWADEE subfamily, an SAWADEE domain is expected in addition to the homeodomain.

This TAP family belongs to the Homeo domain factors structural class of the Helix-turn-helix domains structural superclass, as defined in Plant-TFClass (Blanc-Mathieu et al. 2024)

References:

Catarino, B., Hetherington, A. J., Emms, D. M., Kelly, S., & Dolan, L. (2016). The Stepwise Increase in the Number of Transcription Factor Families in the Precambrian Predated the Diversification of Plants On Land. Molecular Biology and Evolution, 33(11), 2815–2819. https://doi.org/10.1093/molbev/msw155

Romani, F., Reinheimer, R., Florent, S. N., Bowman, J. L., & Moreno, J. E. (2018). Evolutionary history of HOMEODOMAIN LEUCINE ZIPPER transcription factors during plant transition to land. New Phytologist, 219(1), 408–421. https://doi.org/10.1111/nph.15133

Que, F., Wang, G.-L., Li, T., Wang, Y.-H., Xu, Z.-S., & Xiong, A.-S. (2018). Genome-wide identification, expansion, and evolution analysis of homeobox genes and their expression profiles during root development in carrot. Functional & Integrative Genomics, 18(6), 685–700. https://doi.org/10.1007/s10142-018-0624-x

Mukherjee, K., Brocchieri, L., & Burglin, T. R. (2009). A Comprehensive Classification and Evolutionary Analysis of Plant Homeobox Genes. Molecular Biology and Evolution, 26(12), 2775–2794. https://doi.org/10.1093/molbev/msp201

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