Dataset Information

CRFs form protein-protein interactions with each other and with members of the cytokinin signalling pathway in Arabidopsis via the CRF domain.

ABSTRACT: Cytokinin is a plant hormone essential for growth and development. The elucidation of its signalling pathway as a variant of the bacterial two-component signalling system (TCS) has led to a better understanding of how this hormone is involved in general plant processes. A set of cytokinin-regulated transcription factors known as cytokinin response factors (CRFs) have been described as a potential branch emanating from the TCS, yet little is known about how CRFs actually interact with each other and with members of the TCS pathway. Here the interactions of CRF proteins (CRF1-CRF8) using the yeast two-hybrid system and bimolecular fluorescence complementation in planta assays are described. It was found that CRFs are readily able to form both homo- and heterodimers with each other. The first analysis of CRF versus TCS pathway protein interactions is also provided, which indicates that CRFs (CRF1-CRF8) are able specifically to interact directly with most of the Arabidopsis histidine-phosphotransfer proteins (AHP1-AHP5) further solidifying their link to the cytokinin signalling pathway. In addition, the region of CRF proteins involved in these interactions was mapped and it was determined that the clade-specific CRF domain alone is sufficient for these interactions. This is the first described function for the CRF domain in plants.

SUBMITTER: Cutcliffe JW

PROVIDER: S-EPMC3193008 | biostudies-other | 2011 Oct

REPOSITORIES: biostudies-other

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CRFs form protein-protein interactions with each other and with members of the cytokinin signalling pathway in Arabidopsis via the CRF domain.

Cutcliffe James W JW Hellmann Eva E Heyl Alexander A Rashotte Aaron M AM

Journal of experimental botany 20110624 14

Cytokinin is a plant hormone essential for growth and development. The elucidation of its signalling pathway as a variant of the bacterial two-component signalling system (TCS) has led to a better understanding of how this hormone is involved in general plant processes. A set of cytokinin-regulated transcription factors known as cytokinin response factors (CRFs) have been described as a potential branch emanating from the TCS, yet little is known about how CRFs actually interact with each other ...[more]

PMID: 21705390

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Project description:BackgroundCytokinin Response Factors (CRFs) are a small subset of AP2/ERF transcription factor genes shown in Arabidopsis to regulate leaf development as part of the cytokinin signal transduction pathway. This study examines the phylogenetic distribution of CRF genes in other plant species, and attempts to identify the extent of sequence conservation and potential gene function among all CRF genes.ResultsWe identified CRF genes in representatives of all major land plant lineages, including numerous flowering plant taxa in addition to the model systems in which ERF genes have been catalogued. Comparative analysis across this broader sampling has identified strongly conserved amino acid motifs other than the AP2/ERF domain for all CRF proteins as well as signature sequences unique to specific clades of CRF genes. One of these motifs, here designated as the CRF domain, is conserved in and unique to CRF proteins distinguishing them from related genes. We show that this novel domain of approximately 65 amino acids is found in CRF proteins from all groups of land plants and only in CRF genes. Phylogenetic analyses suggest that the evolution of CRF genes has included numerous duplication events. In this phylogenetic context we examine protein evolution including the gain and loss of accessory domains, correlate these molecular evolutionary events with experimental data on cytokinin regulation and speculate on the function and evolution of the CRF domain within AP2/ERF transcription factor proteins. We also tested a prediction drawn from the phylogenetic analyses that four CRF domain containing genes from Tomato, previously unexamined for cytokinin response, are transcriptionally inducible by cytokinin, supporting the link between CRF genes, CRF-specific domains and cytokinin regulation.ConclusionCRF genes can be identified in all lineages of land plants, as a distinct subset of AP2/ERF proteins containing a specific and unique CRF domain. The CRF domain can be used to identify previously unclassified predicted genes or genes identified only as members of the AP2/ERF protein family. CRF domain presence and phylogenetic relatedness to known Arabidopsis CRF genes predicts gene function to some extent.

Project description:The plant hormone cytokinin realizes at least part of its signaling output through the regulation of gene expression. A great part of the early transcriptional regulation is mediated by type-B response regulators, which are transcription factors of the MYB family. Other transcription factors, such as the cytokinin response factors of the AP2/ERF family, have also been shown to be involved in this process. Additional transcription factors mediate distinct parts of the cytokinin response through tissue- and cell-specific downstream transcriptional cascades. In Arabidopsis, only a single cytokinin response element, to which type-B response regulators bind, has been clearly proven so far, which has 5'-GAT(T/C)-3' as a core sequence. This motif has served to construct a synthetic cytokinin-sensitive two-component system response element, which is useful for monitoring the cellular cytokinin status. Insight into the extent of transcriptional regulation has been gained by genome-wide gene expression analyses following cytokinin treatment and from plants having an altered cytokinin content or signaling. This review presents a meta analysis of such microarray data resulting in a core list of cytokinin response genes. Genes encoding type-A response regulators displayed the most stable response to cytokinin, but a number of cytokinin metabolism genes (CKX4, CKX5, CYP735A2, UGT76C2) also belong to them, indicating homeostatic mechanisms operating at the transcriptional level. The cytokinin core response genes are also the target of other hormones as well as biotic and abiotic stresses, documenting crosstalk of the cytokinin system with other hormonal and environmental signaling pathways. The multiple links of cytokinin to diverse functions, ranging from control of meristem activity, hormonal crosstalk, nutrient acquisition, and various stress responses, are also corroborated by a compilation of genes that have been repeatedly found by independent gene expression profiling studies. Such functions are, at least in part, supported by genetic studies.

Dataset Information

CRFs form protein-protein interactions with each other and with members of the cytokinin signalling pathway in Arabidopsis via the CRF domain.

Publications

CRFs form protein-protein interactions with each other and with members of the cytokinin signalling pathway in Arabidopsis via the CRF domain.

Similar Datasets

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