scholarly journals The intervening domain is required for DNA-binding and functional identity of plant MADS transcription factors

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xuelei Lai ◽  
Rosario Vega-Léon ◽  
Veronique Hugouvieux ◽  
Romain Blanc-Mathieu ◽  
Froukje van der Wal ◽  
...  

AbstractThe MADS transcription factors (TF) are an ancient eukaryotic protein family. In plants, the family is divided into two main lineages. Here, we demonstrate that DNA binding in both lineages absolutely requires a short amino acid sequence C-terminal to the MADS domain (M domain) called the Intervening domain (I domain) that was previously defined only in type II lineage MADS. Structural elucidation of the MI domains from the floral regulator, SEPALLATA3 (SEP3), shows a conserved fold with the I domain acting to stabilise the M domain. Using the floral organ identity MADS TFs, SEP3, APETALA1 (AP1) and AGAMOUS (AG), domain swapping demonstrate that the I domain alters genome-wide DNA-binding specificity and dimerisation specificity. Introducing AG carrying the I domain of AP1 in the Arabidopsis ap1 mutant resulted in strong complementation and restoration of first and second whorl organs. Taken together, these data demonstrate that the I domain acts as an integral part of the DNA-binding domain and significantly contributes to the functional identity of the MADS TF.

2021 ◽  
Author(s):  
Xuelei Lai ◽  
Rosario Vega-Leon ◽  
Veronique Hugouvieux ◽  
Romain Blanc-Mathieu ◽  
Froukje van der Wal ◽  
...  

Abstract The MADS transcription factors (TF) are an ancient protein family with a high degree of sequence identity that bind almost identical DNA sequences across all eukaryotic kingdoms of life, yet fulfill dramatically different physiological roles. In plants, the family is divided into two main lineages, type I and II, based on sequence conservation of the DNA-binding MADS-box domain (M domain) with yeast and animal M domains. Here, we demonstrate that DNA binding in both lineages absolutely requires a short amino acid sequence C-terminal to the M domain called the Intervening domain (I domain) in type II MADS. Structural elucidation of the MI domains from the floral regulator, SEPALLATA3 (SEP3), shows a highly conserved MADS-box fold with the I domain forming an alpha helix and acting to stabilize the M domain. Based on secondary structure prediction, sequences fulfilling the same function as the SEP3 I domain can be found in both lineages of plant MADS TFs, suggesting the I domain is a conserved and required part of the DNA-binding domain. Using the floral organ identity MADS TFs, SEP3, APETALA1 (AP1) and AGAMOUS (AG), domain swapping demonstrate that the I domain alters DNA-binding specificity based on seq-DAP-seq experiments. Yeast 2-hybrid experiments further revealed the role of the I domain in dimerization specificity. Surprisingly, introducing AG carrying the I domain of AP1 in the Arabidopsis ap1 mutant, resulted in a high degree of complementation and restoration of first and second whorl organs. Taken together, these data demonstrate that the I domain acts both as an integral part of the DNA-binding domain and strongly contributes to the functional identity of the MADS TF.


2020 ◽  
Vol 48 (17) ◽  
pp. 9637-9648
Author(s):  
Xuelei Lai ◽  
Arnaud Stigliani ◽  
Jérémy Lucas ◽  
Véronique Hugouvieux ◽  
François Parcy ◽  
...  

Abstract The MADS transcription factors (TF), SEPALLATA3 (SEP3) and AGAMOUS (AG) are required for floral organ identity and floral meristem determinacy. While dimerization is obligatory for DNA binding, SEP3 and SEP3–AG also form tetrameric complexes. How homo and hetero-dimerization and tetramerization of MADS TFs affect genome-wide DNA-binding and gene regulation is not known. Using sequential DNA affinity purification sequencing (seq-DAP-seq), we determined genome-wide binding of SEP3 homomeric and SEP3–AG heteromeric complexes, including SEP3Δtet-AG, a complex with a SEP3 splice variant, SEP3Δtet, which is largely dimeric and SEP3–AG tetramer. SEP3 and SEP3–AG share numerous bound regions, however each complex bound unique sites, demonstrating that protein identity plays a role in DNA-binding. SEP3–AG and SEP3Δtet-AG share a similar genome-wide binding pattern; however the tetrameric form could access new sites and demonstrated a global increase in DNA-binding affinity. Tetramerization exhibited significant cooperative binding with preferential distances between two sites, allowing efficient binding to regions that are poorly recognized by dimeric SEP3Δtet-AG. By intersecting seq-DAP-seq with ChIP-seq and expression data, we identified unique target genes bound either in SEP3–AG seq-DAP-seq or in SEP3/AG ChIP-seq. Seq-DAP-seq is a versatile genome-wide technique and complements in vivo methods to identify putative direct regulatory targets.


2021 ◽  
Author(s):  
Xuelei Lai ◽  
Rosario Vega-Leon ◽  
Veronique Hugouvieux ◽  
Romain Blanc-Mathieu ◽  
Froukje van der Wal ◽  
...  

AbstractThe MADS transcription factors (TF) are an ancient protein family with a high degree of sequence identity that bind almost identical DNA sequences across all eukaryotic kingdoms of life, yet fulfill dramatically different physiological roles. In plants, the family is divided into two main lineages, type I and II, based on sequence conservation of the DNA-binding MADS-box domain (M domain) with yeast and animal M domains. Here, we demonstrate that DNA binding in both lineages absolutely requires a short amino acid sequence C-terminal to the M domain called the Intervening domain (I domain) in type II MADS. Structural elucidation of the MI domains from the floral regulator, SEPALLATA3 (SEP3), shows a highly conserved MADS-box fold with the I domain forming an alpha helix and acting to stabilize the M domain. Based on secondary structure prediction, sequences fulfilling the same function as the SEP3 I domain can be found in both lineages of plant MADS TFs, suggesting the I domain is a conserved and required part of the DNA-binding domain. Using the floral organ identity MADS TFs, SEP3, APETALA1 (AP1) and AGAMOUS (AG), domain swapping demonstrate that the I domain alters DNA-binding specificity based on seq-DAP-seq experiments. Yeast 2-hybrid experiments further revealed the role of the I domain in dimerization specificity. Surprisingly, introducing AG carrying the I domain of AP1 in the Arabidopsis ap1 mutant, resulted in a high degree of complementation and restoration of first and second whorl organs. Taken together, these data demonstrate that the I domain acts both as an integral part of the DNA-binding domain and strongly contributes to the functional identity of the MADS TF.


1997 ◽  
Vol 8 (7) ◽  
pp. 1243-1259 ◽  
Author(s):  
J L Riechmann ◽  
E M Meyerowitz

The MADS domain homeotic proteins APETALA1 (AP1), APETALA3 (AP3), PISTILLATA (PI), and AGAMOUS (AG) combinatorially specify the identity of Arabidopsis floral organs. AP1/AP1, AG/AG, and AP3/PI dimers bind to similar CArG box sequences; thus, differences in DNA-binding specificity among these proteins do not seem to be the origin of their distinct organ identity properties. To assess the overall contribution that specific DNA binding could make to their biological specificity, we have generated chimeric genes in which the amino-terminal half of the MADS domain of AP1, AP3, PI, and AG was substituted by the corresponding sequences of human SRF and MEF2A proteins. In vitro DNA-binding assays reveal that the chimeric proteins acquired the respective, and distinct, DNA-binding specificity of SRF or MEF2A. However, ectopic expression of the chimeric genes reproduces the dominant gain-of-function phenotypes exhibited by plants ectopically expressing the corresponding Arabidopsis wild-type genes. In addition, both the SRF and MEF2 chimeric genes can complement the pertinent ap1-1, ap3-3, pi-1, or ag-3 mutations to a degree similar to that of AP1, AP3, PI, and AG when expressed under the control of the same promoter. These results indicate that determination of floral organ identity by the MADS domain homeotic proteins AP1, AP3, PI, and AG is independent of their DNA-binding specificity. In addition, the DNA-binding experiments show that either one of the two MADS domains of a dimer can be sufficient to confer a particular DNA-binding specificity to the complex and that sequences outside the amino-terminal basic region of the MADS domain can, in some cases, contribute to the DNA-binding specificity of the proteins.


1993 ◽  
Vol 13 (7) ◽  
pp. 3999-4010 ◽  
Author(s):  
M Merika ◽  
S H Orkin

GATA-binding proteins constitute a family of transcription factors that recognize a target site conforming to the consensus WGATAR (W = A or T and R = A or G). Here we have used the method of polymerase chain reaction-mediated random site selection to assess in an unbiased manner the DNA-binding specificity of GATA proteins. Contrary to our expectations, we show that GATA proteins bind a variety of motifs that deviate from the previously assigned consensus. Many of the nonconsensus sequences bind protein with high affinity, equivalent to that of conventional GATA motifs. By using the selected sequences as probes in the electrophoretic mobility shift assay, we demonstrate overlapping, but distinct, sequence preferences for GATA family members, specified by their respective DNA-binding domains. Furthermore, we provide additional evidence for interaction of amino and carboxy fingers of GATA-1 in defining its binding site. By performing cotransfection experiments, we also show that transactivation parallels DNA binding. A chimeric protein containing the finger domain of areA and the activation domains of GATA-1 is capable of activating transcription in mammalian cells through GATA motifs. Our findings suggest a mechanism by which GATA proteins might selectively regulate gene expression in cells in which they are coexpressed.


Plant Science ◽  
2005 ◽  
Vol 169 (4) ◽  
pp. 785-797 ◽  
Author(s):  
Addie N. Olsen ◽  
Heidi A. Ernst ◽  
Leila Lo Leggio ◽  
Karen Skriver

1997 ◽  
Vol 17 (5) ◽  
pp. 2876-2887 ◽  
Author(s):  
A G West ◽  
P Shore ◽  
A D Sharrocks

The serum response factor (SRF) and myocyte enhancer factor 2A (MEF2A) represent two human members of the MADS-box transcription factor family. Each protein has a distinct biological function which is reflected by the distinct specificities of the proteins for coregulatory protein partners and DNA-binding sites. In this study, we have investigated the mechanism of DNA binding utilized by these two related transcription factors. Although SRF and MEF2A belong to the same family and contain related DNA-binding domains, their DNA-binding mechanisms differ in several key aspects. In contrast to the dramatic DNA bending induced by SRF, MEF2A induces minimal DNA distortion. A combination of loss- and gain-of-function mutagenesis identified a single amino acid residue located at the N terminus of the recognition helices as the critical mediator of this differential DNA bending. This residue is also involved in determining DNA-binding specificity, thus indicating a link between DNA bending and DNA-binding specificity determination. Furthermore, different basic residues within the putative recognition alpha-helices are critical for DNA binding, and the role of the C-terminal extensions to the MADS box in dimerization between SRF and MEF2A also differs. These important differences in the molecular interactions of SRF and MEF2A are likely to contribute to their differing roles in the regulation of specific gene transcription.


2013 ◽  
Vol 42 (4) ◽  
pp. 2138-2146 ◽  
Author(s):  
Jose M. Muiño ◽  
Cezary Smaczniak ◽  
Gerco C. Angenent ◽  
Kerstin Kaufmann ◽  
Aalt D.J. van Dijk

Abstract Plant MADS-domain transcription factors act as key regulators of many developmental processes. Despite the wealth of information that exists about these factors, the mechanisms by which they recognize their cognate DNA-binding site, called CArG-box (consensus CCW6GG), and how different MADS-domain proteins achieve DNA-binding specificity, are still largely unknown. We used information from in vivo ChIP-seq experiments, in vitro DNA-binding data and evolutionary conservation to address these important questions. We found that structural characteristics of the DNA play an important role in the DNA binding of plant MADS-domain proteins. The central region of the CArG-box largely resembles a structural motif called ‘A-tract’, which is characterized by a narrow minor groove and may assist bending of the DNA by MADS-domain proteins. Periodically spaced A-tracts outside the CArG-box suggest additional roles for this structure in the process of DNA binding of these transcription factors. Structural characteristics of the CArG-box not only play an important role in DNA-binding site recognition of MADS-domain proteins, but also partly explain differences in DNA-binding specificity of different members of this transcription factor family and their heteromeric complexes.


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