A conserved leucine zipper-like motif accounts for strong tetramerization capabilities of SEPALLATA-like MADS-domain transcription factors

Rümpler, Florian; Theißen, Günter; Melzer, Rainer

doi:10.1093/jxb/ery063

Cited by 26 publications

(56 citation statements)

References 51 publications

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“…If in vitro translated SEP3 full length protein was co-incubated with a radioactively labeled DNA probe that carries two MIKC-type MTF DNA-binding sites (so called CArG-boxes), a single retarded fraction appeared close to the 1 kb fragment of the DNA marker ( Figure 5b, lane 1). As has been demonstrated in several previous studies, this fraction constitutes a SEP3 tetramer bound to both DNA-binding sites via looping the DNA in between both binding sites (Jetha et al, 2014;Rümpler et al, 2018). When purified SAP54 was added to the binding reaction a supershift was observed ( Figure 5b, lane 2).…”

Section: Sap54 Preferentially Targets Multimers Of Mikc-type Mtfssupporting

confidence: 77%

“…This observation could probably even help to explain the target specificity of SAP54. For several known targets of SAP54 (SEP1, SEP2, SEP3, and SEP4) it has been shown that they are capable of forming DNA-bound homotetramers (Jetha et al, 2014;Rümpler et al, 2018), whereas AP3 and PI that are unable to form homotetramers Rümpler et al, 2018) are not bound by SAP54 (MacLean et al, 2014). Furthermore, there is evidence that SAP54 binds not only to MIKC-type MTFs, but also to RAD23C and RAD23D, i.e.…”

Section: Discussionmentioning

confidence: 99%

“…According to X-ray crystallographic data of the MIKC-type MTF SEPALLATA3 (SEP3) from A. thaliana, which is a target of SAP54, the K-domain folds into two coiled-coils separated by a short kink (Puranik et al, 2014). As the amino acid sequence within the K-domain is highly conserved among MIKC-type MTFs it appears very likely that the K-domains of most MIKC-type MTFs fold in a structure very similar to that determined for SEP3 (Rümpler et al, 2018).…”

Section: Introductionmentioning

confidence: 97%

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Structural requirements of the phytoplasma effector protein SAP54 for causing homeotic transformation of floral organs

Aurin¹,

Haupt

Goerlach

et al. 2019

Preprint

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SIGNIFICANCE STATEMENTPhytoplasmas are bacterial plant pathogens that cause devastating diseases in crops and ornamental plants by the secretion of effector proteins such as SAP54, which leads to the degradation of some floral homeotic proteins. Our study clarifies the structural requirements of SAP54 function and illuminates the molecular mode of interaction and thus may ultimately help to develop treatments against some devastating plant diseases. SummaryPhytoplasmas are intracellular bacterial plant pathogens that cause devastating diseases in crops and ornamental plants by the secretion of effector proteins. One of these effector proteins, termed SECRETED ASTER YELLOWS-WITCHES' BROOM PROTEIN 54 (SAP54), leads to the degradation of a specific subset of floral homeotic proteins of the MIKC-type MADSdomain family via the ubiquitin-proteasome pathway. In consequence, the developing flowers show the homeotic transformation of floral organs into vegetative leaf-like structures. The molecular mechanism of SAP54 action involves physical binding to the keratin-like K-domain of MIKC-type proteins, and to some RAD23 proteins, which translocate ubiquitylated substrates to the proteasome. The structural requirements and specificity of SAP54 function are poorly understood, however. Here we report, based on biophysical and molecular biological analyses, that SAP54 folds into α-helical structures. We also show that the insertion of helixbreaking mutations disrupts correct folding of SAP54, which interferes with the ability of SAP54 to bind to its target proteins and to cause disease phenotypes in vivo. Surprisingly, dynamic light scattering data together with electrophoretic mobility shift assays suggest that SAP54 preferentially binds to multimeric complexes of MIKC-type proteins rather than to dimers or monomers of these proteins. Together with literature data this finding suggests that MIKC-type proteins and SAP54 constitute multimeric α-helical coiled-coils, possibly also involving other partners such as RAD23 proteins. Our investigations clarify the structurefunction relationship of an important phytoplasma effector protein and thus may ultimately help to develop treatments against some devastating plant diseases.

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Section: Sap54 Preferentially Targets Multimers Of Mikc-type Mtfssupporting

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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Structural requirements of the phytoplasma effector protein SAP54 for causing homeotic transformation of floral organs

Aurin¹,

Haupt

Goerlach

et al. 2019

Preprint

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“…Tomato RIN might also be expected to act in concert with other MADS‐box proteins. MADS TFs bind target CArG boxes in DNA and possess a versatile oligomerization interface, which allows the formation of homo‐ and heterodimers and tetramers with other K domain‐containing MADS TFs (Puranik et al ., ) and a conserved leucine zipper‐like motif in the K domain contributes to the strong dimerization capabilities of SEP‐like MADS‐box factors (Rümpler et al ., ). If two MADS dimers bound at different sites in DNA come into close contact as a result of chromatin conformation, tetramerization also could occur, enabling the MADS TFs to act as a dynamic interaction network (Puranik et al ., ), thus making it possible for multiple CArG boxes in the gene promoter regions of different genes to facilitate the formation of transcription factories (Sutherland & Bickmore, ).…”

Section: The Importance Of Mads‐rin In Controlling Ripeningmentioning

confidence: 97%

A critical evaluation of the role of ethylene and MADS transcription factors in the network controlling fleshy fruit ripening

2018

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Contents Summary1724I.Introduction1725II.Ripening genes1725III.The importance of ethylene in controlling ripening1727IV.The importance of MADS‐RIN in controlling ripening1729V.Interactions between components of the ripening regulatory network1734VI.Conclusions1736Acknowledgements1738Author contributions1738References1738 Summary Understanding the regulation of fleshy fruit ripening is biologically important and provides insights and opportunities for controlling fruit quality, enhancing nutritional value for animals and humans, and improving storage and waste reduction. The ripening regulatory network involves master and downstream transcription factors (TFs) and hormones. Tomato is a model for ripening regulation, which requires ethylene and master TFs including NAC‐NOR and the MADS‐box protein MADS‐RIN. Recent functional characterization showed that the classical RIN‐MC gene fusion, previously believed to be a loss‐of‐function mutation, is an active TF with repressor activity. This, and other evidence, has highlighted the possibility that MADS‐RIN itself is not important for ripening initiation but is required for full ripening. In this review, we discuss the diversity of components in the control network, their targets, and how they interact to control initiation and progression of ripening. Both hormones and individual TFs affect the status and activity of other network participants, which changes overall network signaling and ripening outcomes. MADS‐RIN, NAC‐NOR and ethylene play critical roles but there are still unanswered questions about these and other TFs. Further attention should be paid to relationships between ethylene, MADS‐RIN and NACs in ripening control.

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“…As mentioned previously, Arabidopsis LFY requires oligomerization activity in order to bind to low affinity LFY binding sites in closed chromatin regions [ 59 ]. Similarly, MADS-box TFs are able to tetramerize and bind DNA cooperatively, increasing their DNA-binding affinity [ 119 , 132 ]. In addition, a mechanism similar to histone octamer binding in which DNA wraps around the MADS-box tetramer has been proposed for plant MADS-box TFs, although this is highly speculative [ 133 ].…”

Section: Mechanism Of Actionmentioning

confidence: 99%

Pioneer Factors in Animals and Plants—Colonizing Chromatin for Gene Regulation

et al. 2018

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Unlike most transcription factors (TF), pioneer TFs have a specialized role in binding closed regions of chromatin and initiating the subsequent opening of these regions. Thus, pioneer TFs are key factors in gene regulation with critical roles in developmental transitions, including organ biogenesis, tissue development, and cellular differentiation. These developmental events involve some major reprogramming of gene expression patterns, specifically the opening and closing of distinct chromatin regions. Here, we discuss how pioneer TFs are identified using biochemical and genome-wide techniques. What is known about pioneer TFs from animals and plants is reviewed, with a focus on the strategies used by pioneer factors in different organisms. Finally, the different molecular mechanisms pioneer factors used are discussed, highlighting the roles that tertiary and quaternary structures play in nucleosome-compatible DNA-binding.

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A conserved leucine zipper-like motif accounts for strong tetramerization capabilities of SEPALLATA-like MADS-domain transcription factors

Abstract: The strong tetramerization capabilities of the floral homeotic MADS-domain protein SEP3 largely depend on leucine residues at just a few key positions within the protein–protein interacting keratin-like domain.

Cited by 26 publications

References 51 publications

Structural requirements of the phytoplasma effector protein SAP54 for causing homeotic transformation of floral organs

Structural requirements of the phytoplasma effector protein SAP54 for causing homeotic transformation of floral organs

A critical evaluation of the role of ethylene and MADS transcription factors in the network controlling fleshy fruit ripening

Pioneer Factors in Animals and Plants—Colonizing Chromatin for Gene Regulation

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