MBF1 Family from Maize

Required domains for MBF1 family:PF08523

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Multiprotein Bridging Factor 1 (MBF1) was first purified from silkworm silk glands as a non- DNA binding transcription cofactor (Li et al., 1994). It belongs to Helix-Turn-Helix superfamily of proteins consisting of N-terminal domain which interacts with transcription factors and so called as ‘Multiprotein Bridging Factor 1, N-terminal’ and conserved TATA box binding protein (TBP) binding C-terminal helix-turn-helix domain (Aravind et al., 2005, Jaimes-Miranda and Chávez Montes., 2020). MBF1 enhances transcription activation by bridging a basic region/leucine zipper (bZIP) type transcription factor and TBP in yeast (Takemaru et al., 1998), Drosophila (Liu et al., 2003) and human (Kabe et al., 1999). Arabidopsis genome encodes three MBF1 family coactivators, MBF1a, MBF1b and MBF1c classified into group I consisting of  MBF1a, MBF1b  due to similar gene structure and MBF1c belonging to group II, and these MBFs showed tissue specific expression profiles indicating different functions (Tsuda et al., 2004, Tsuda and Yamazaki., 2004).

Arabidopsis, MBF1a gene encodes 16 kDa protein which is 82.4% identical to maize Salt Tolerance 41 (SAT41) which plays a role in response to elevated salt tolerance. AtMBF1a expression was induced in response to elevated salt and glucose levels. Also overexpression of MBF1a increased resistance to fungal disease and insensitivity to glucose. Thus implying MBF1a role in biotic and abiotic stress tolerance in Arabidopsis (Kim et al., 2007). Arabidopsis MBF1c is a key regulator of heat tolerance. In response to heat it is localized to the nucleus and functions upstream of SA, trehalose, ethylene and PR related protein 1. MBF1c interacts with heat inducible TPS5 (Trehalose Phosphate Synthase 5) component of trehalose signaling pathway and TPS5 mutants are thermosensitive. However, MBF1c does not play a role in expression of any HSFs (Suzuki et al., 2008). Transgenic Arabidopsis overexpressing AtMBF1 fused to an active transcription repression domain (SRDX) resulted in suppression of leaves cell expansion during late leaf development stage along with lower ploidy levels in the leaves, also elevated expression of negative regulators of endoreduplication were observed. Thus suggesting AtMBF1s role in cell expansion and ploidy regulation during leaf development stage (Tojo et al., 2008). Arabidopsis MBF1s triple knock down mutant abc-  showed increased sensitivity to hydrogen peroxide and methyl viologen oxidative stress and sorbitol mediated osmotic stress. Overexpression of AtMBF1c in abc- triple mutant resulted in partial or complete phenotype rescue based on physiological or development conditions. ABR1, a member of the AP2/ERF family acting as a ABA repressor, is regulated by AtMBF1s. Thus, AtMBF1s functions as a crosstalk regulatory component for ethylene, ABA and stress signal pathways (Arce et al., 2009). In response to heat stress, based on molecular dynamic simulations AtMBF1c N-terminal region comprising of Asparagine 67, Threonine 68, Lysine 69 and Lysine 70 residues specifically binds to CTAGA binding element in the minor groove of the DNA to form stable DNA-MBF1 complex (Jaimes-Miranda et al., 2020).

Overexpression of wheat, Triticum aestivum L. MBF1c in yeast and rice resulted in increased thermotolerance. Also, since TaMBF1c promoter region contained three heat shock elements (HSEs) and Trehalose phosphate synthase gene, their transcript levels were higher in TaMBF1c transgenic lines as compared to wild type in response to heat stress (Qin et al., 2014). Wild relative of cultivated barley, Hordeum brevisubulatum genome encodes three MBF1 proteins- HbMBF1a, HbMBF1band HbMBF1c. HbMBF1a was identified from transcriptomic data of H. brevisubulatum exposed to salt stress. Overexpression of HbMBF1a in Arabidopsis thaliana, resulted in enhanced salt tolerance and ABA insensitivity along with significant upregulation of stress related genes (Zhang et al., 2020).

Last updated June 2023 by Ankita Abnave


Li FQ, Ueda H, Hirose S. Mediators of activation of fushi tarazu gene transcription by BmFTZ-F1. Mol Cell Biol. 1994 May;14(5):3013-21. doi: 10.1128/mcb.14.5.3013-3021.1994. PMID: 8164657; PMCID: PMC358669.

Takemaru K, Harashima S, Ueda H, Hirose S. Yeast coactivator MBF1 mediates GCN4-dependent transcriptional activation. Mol Cell Biol. 1998 Sep;18(9):4971-6. doi: 10.1128/MCB.18.9.4971. PMID: 9710580; PMCID: PMC109081.

Liu QX, Jindra M, Ueda H, Hiromi Y, Hirose S. Drosophila MBF1 is a co-activator for Tracheae Defective and contributes to the formation of tracheal and nervous systems. Development. 2003 Feb;130(4):719-28. doi: 10.1242/dev.00297. PMID: 12506002.

Kabe Y, Goto M, Shima D, Imai T, Wada T, Morohashi Ki, Shirakawa M, Hirose S, Handa H. The role of human MBF1 as a transcriptional coactivator. J Biol Chem. 1999 Nov 26;274(48):34196-202. doi: 10.1074/jbc.274.48.34196. PMID: 10567391.

Tsuda K, Tsuji T, Hirose S, Yamazaki K. Three Arabidopsis MBF1 homologs with distinct expression profiles play roles as transcriptional co-activators. Plant Cell Physiol. 2004 Feb;45(2):225-31. doi: 10.1093/pcp/pch017. PMID: 14988493.

Kim MJ, Lim GH, Kim ES, Ko CB, Yang KY, Jeong JA, Lee MC, Kim CS. Abiotic and biotic stress tolerance in Arabidopsis overexpressing the multiprotein bridging factor 1a (MBF1a) transcriptional coactivator gene. Biochem Biophys Res Commun. 2007 Mar 9;354(2):440-6. doi: 10.1016/j.bbrc.2006.12.212. Epub 2007 Jan 9. PMID: 17234157.

Suzuki N, Bajad S, Shuman J, Shulaev V, Mittler R. The transcriptional co-activator MBF1c is a key regulator of thermotolerance in Arabidopsis thaliana. J Biol Chem. 2008 Apr 4;283(14):9269-75. doi: 10.1074/jbc.M709187200. Epub 2008 Jan 17. PMID: 18201973.

Tojo T, Tsuda K, Yoshizumi T, Ikeda A, Yamaguchi J, Matsui M, Yamazaki K. Arabidopsis MBF1s control leaf cell cycle and its expansion. Plant Cell Physiol. 2009 Feb;50(2):254-64. doi: 10.1093/pcp/pcn187. Epub 2008 Dec 2. PMID: 19050034.

Arce DP, Godoy AV, Tsuda K, Yamazaki K, Valle EM, Iglesias MJ, Di Mauro MF, Casalongué CA. The analysis of an Arabidopsis triple knock-down mutant reveals functions for MBF1 genes under oxidative stress conditions. J Plant Physiol. 2010 Feb 15;167(3):194-200. doi: 10.1016/j.jplph.2009.09.003. Epub 2009 Sep 26. PMID: 19783066.

Aravind L, Anantharaman V, Balaji S, Babu MM, Iyer LM. The many faces of the helix-turn-helix domain: transcription regulation and beyond. FEMS Microbiol Rev. 2005 Apr;29(2):231-62. doi: 10.1016/j.femsre.2004.12.008. PMID: 15808743.

Tsuda K, Yamazaki K. Structure and expression analysis of three subtypes of Arabidopsis MBF1 genes. Biochim Biophys Acta. 2004 Oct 5;1680(1):1-10. doi: 10.1016/j.bbaexp.2004.08.004. PMID: 15451167.

Jaimes-Miranda F, Chávez Montes RA. The plant MBF1 protein family: a bridge between stress and transcription. J Exp Bot. 2020 Mar 25;71(6):1782-1791. doi: 10.1093/jxb/erz525. PMID: 32037452; PMCID: PMC7094072.

Salgado-Blanco D, López-Urías F, Ovando-Vázquez C, Jaimes-Miranda F. DNA-MBF1 study using molecular dynamics simulations : On the road to understanding the heat stress response in DNA-protein interactions in plants. Eur Biophys J. 2021 Dec;50(8):1055-1067. doi: 10.1007/s00249-021-01565-x. Epub 2021 Aug 13. PMID: 34387715.

Qin D, Wang F, Geng X, Zhang L, Yao Y, Ni Z, Peng H, Sun Q. Overexpression of heat stress-responsive TaMBF1c, a wheat (Triticum aestivum L.) Multiprotein Bridging Factor, confers heat tolerance in both yeast and rice. Plant Mol Biol. 2015 Jan;87(1-2):31-45. doi: 10.1007/s11103-014-0259-9. Epub 2014 Oct 18. PMID: 25326264.

Zhang L, Wang Y, Zhang Q, Jiang Y, Zhang H, Li R. Overexpression of HbMBF1a, encoding multiprotein bridging factor 1 from the halophyte Hordeum brevisubulatum, confers salinity tolerance and ABA insensitivity to transgenic Arabidopsis thaliana. Plant Mol Biol. 2020 Jan;102(1-2):1-17. doi: 10.1007/s11103-019-00926-7. Epub 2019 Oct 26. PMID: 31655970; PMCID: PMC6976555.




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