The DOF (DNA binding with one finger) family of plant-specific transcription factors (TF) was first identified in maize in 1995 (Yanagisawa 1995). First identified as a protein named MNB1a that could bind to the Cauliflower mosaic 35S promoter, it was later renamed PROLAMIN BINDING FACTOR (PBF) or DOF3 that controls the endosperm-specific expression of the zein (prolamin) genes in maize. The DOF TF family is characterized by a highly conserved DNA binding domain (DOF domain), consisting of a CX2C-X21-CX2C motif, which is able to form a zinc finger structure. All DOF proteins bind the highly conserved (T/A)AAAG consensus motif, identified through binding site-selection experiments using the maize DOF proteins DOF1, DOF2, and DOF3 (PBF1) (Yanagisawa and Schmidt 1999). DOF proteins can act in concert with other transcription factors to bind DNA.  The maize ZmDOF3(PBF1) protein from maize was shown to interact with ZmO2 (Opaque2, ZmbZIP1) a bZIP type transcription factor (Vicente-Carbajosa et al., 1997). The GLM motif in the promoters of maize zein genes is recognised and bound by ZmO2 and mutations of the maize O2 gene result in a endosperm-specific decreased expression of the maize zein genes (​​ et al 1992).  A 2015 study identified 46 putative Dof genes from maize. The predicted ZmDof genes were non-randomly distributed within their chromosomes, and segmental duplication seemed to be the prevalent mechanism for their expansion. Many cis-elements responding to light, endosperm specific gene expression, hormone, meristem specific expression, and stress were also found in the 1,000 bps upstream sequences of promoter regions (Chen and Cao 2015).

Since their initial discovery in maize, DOF proteins have been shown to be present in the whole plant kingdom, including the unicellular alga Chlamydomonas reinhardtii (Ruta et al., 2020). Dof proteins have diverse roles in gene expression in plants including light phytohormone and defense responses seed development and germination. Based on the structural diversity indicated by the complete catalog of Arabidopsis Dof proteins Dof genes appear to have evolved multiple times preceding and paralleling the diversification of angiosperms. Several Dofs play central roles in stress tolerance by regulating the expression of stress-responsive genes via the DOFCORE element or by interacting with other regulatory proteins. Moreover, Dofs act as a key regulatory hub of several phytohormone pathways, integrating abscisic acid, jasmonate, SA and redox signaling in response to many abiotic stresses (Wang et al., 2022).

Last updated June 2023 by John Gray

References:

Ruta V, Longo C, Lepri A, De Angelis V, Occhigrossi S, Costantino P, Vittorioso P. The DOF Transcription Factors in Seed and Seedling Development. Plants (Basel). 2020 Feb 8;9(2):218. doi: 10.3390/plants9020218. PMID: 32046332; PMCID: PMC7076670.

Yanagisawa S. A novel DNA-binding domain that may form a single zinc finger motif. Nucleic Acids Res. 1995 Sep 11;23(17):3403-10. doi: 10.1093/nar/23.17.3403. PMID: 7567449; PMCID: PMC307217.

Yanagisawa S, Schmidt RJ. Diversity and similarity among recognition sequences of Dof transcription factors. Plant J. 1999 Jan;17(2):209-14. doi: 10.1046/j.1365-313x.1999.00363.x. PMID: 10074718.

Wang Z, Wong DCJ, Chen Z, Bai W, Si H, Jin X. Emerging Roles of Plant DNA-Binding With One Finger Transcription Factors in Various Hormone and Stress Signaling Pathways. Front Plant Sci. 2022 May 13;13:844201. doi: 10.3389/fpls.2022.844201. PMID: 35668792; PMCID: PMC9165642.

Vicente-Carbajosa J, Moose SP, Parsons RL, Schmidt RJ. A maize zinc-finger protein binds the prolamin box in zein gene promoters and interacts with the basic leucine zipper transcriptional activator Opaque2. Proc Natl Acad Sci U S A. 1997 Jul 8;94(14):7685-90. doi: 10.1073/pnas.94.14.7685. PMID: 9207153; PMCID: PMC23883.

Schmidt RJ, Ketudat M, Aukerman MJ, Hoschek G. Opaque-2 is a transcriptional activator that recognizes a specific target site in 22-kD zein genes. Plant Cell. 1992 Jun;4(6):689-700. doi: 10.1105/tpc.4.6.689. PMID: 1392590; PMCID: PMC160165.

Chen, Y., Cao, J. Comparative Analysis of Dof Transcription Factor Family in Maize. Plant Mol Biol Rep 33, 1245–1258 (2015). https://doi.org/10.1007/s11105-014-0835-9