Homeodomain-leucine Zipper Proteins Interact with a Plant Homologue of the Transcriptional Co-activator Multiprotein Bridging Factor 1

Zanetti, Margherita; Chan, Raquel L.; Godoy, Andrea Verónica; González, Daniel H.; Casalongué, Claudia Anahí

doi:10.5483/bmbrep.2004.37.3.320

Cited by 9 publications

(7 citation statements)

References 34 publications

(55 reference statements)

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“…Additional support to the importance of the CTR was provided by Sakuma et al [36]; they identified that the recessive allele vrs1 , which causes the six-rowed phenotype in barley, encodes an HD-Zip I TF 14 residues shorter in the CTR than its paralogous gene HvHox2 (both share 88% of identity in the whole protein), which was caused by a 300-bp insertion that introduced a stop codon. These authors identified a conserved motif within these 14 amino acids and suggested that this motif could interact with certain classes of co-activators in order to exert its biological function [36,37]. …”

Section: Discussionmentioning

confidence: 99%

“…Good examples of the importance of this regions are VRS1 [36], which lacks a motif in the CTR in relation to HvHox2, and the protein without the last 14 residues of the CTR that mimics the tl mutation [38]; in both cases the deletions correspond to AHA-like sequences. Finally, the different versions of AHA motifs found, shared by the members of each group, may be responsible for the interaction with different co-activators or members of the basal transcriptional machinery [37], and thus provide a source of functional divergence among HD-Zip I proteins together with differential expression patterns in some cases.…”

Section: Discussionmentioning

confidence: 99%

“…HvHox2 exhibits 14 additional amino acids compared with VRS1. These authors identified a conserved motif in this portion of the protein and suggested that it could interact with certain classes of co-activators in order to exert its biological function, as it has been proposed for HAHB4 [36,37]. …”

Section: Introductionmentioning

confidence: 99%

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Uncharacterized conserved motifs outside the HD-Zip domain in HD-Zip subfamily I transcription factors; a potential source of functional diversity

et al. 2011

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BackgroundPlant HD-Zip transcription factors are modular proteins in which a homeodomain is associated to a leucine zipper. Of the four subfamilies in which they are divided, the tested members from subfamily I bind in vitro the same pseudopalindromic sequence CAAT(A/T)ATTG and among them, several exhibit similar expression patterns. However, most experiments in which HD-Zip I proteins were over or ectopically expressed under the control of the constitutive promoter 35S CaMV resulted in transgenic plants with clearly different phenotypes. Aiming to elucidate the structural mechanisms underlying such observation and taking advantage of the increasing information in databases of sequences from diverse plant species, an in silico analysis was performed. In addition, some of the results were also experimentally supported.ResultsA phylogenetic tree of 178 HD-Zip I proteins together with the sequence conservation presented outside the HD-Zip domains allowed the distinction of six groups of proteins. A motif-discovery approach enabled the recognition of an activation domain in the carboxy-terminal regions (CTRs) and some putative regulatory mechanisms acting in the amino-terminal regions (NTRs) and CTRs involving sumoylation and phosphorylation. A yeast one-hybrid experiment demonstrated that the activation activity of ATHB1, a member of one of the groups, is located in its CTR. Chimerical constructs were performed combining the HD-Zip domain of one member with the CTR of another and transgenic plants were obtained with these constructs. The phenotype of the chimerical transgenic plants was similar to the observed in transgenic plants bearing the CTR of the donor protein, revealing the importance of this module inside the whole protein.ConclusionsThe bioinformatical results and the experiments conducted in yeast and transgenic plants strongly suggest that the previously poorly analyzed NTRs and CTRs of HD-Zip I proteins play an important role in their function, hence potentially constituting a major source of functional diversity among members of this subfamily.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Uncharacterized conserved motifs outside the HD-Zip domain in HD-Zip subfamily I transcription factors; a potential source of functional diversity

et al. 2011

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“…The role of the motif 8 is not annotated in the protein family (Pfam) database (http://pfam.sanger.ac.uk/), but its loss may be sufficient to differentiate the functions of the Vrs1 and HvHox2 gene products. Transcriptional co-activators enhance transcription by interacting with both general and gene-specific transcription factors (Zanetti et al 2004). Thus, motif 8 in HvHOX2 could interact with certain classes of transcriptional co-activators, and then act as an activator for the transcription of downstream genes, while VRS1 would not be able to replicate this interaction as it lacks motif 8.…”

Section: Discussionmentioning

confidence: 99%

Duplication of a well-conserved homeodomain-leucine zipper transcription factor gene in barley generates a copy with more specific functions

Sakuma

Pourkheirandish

Matsumoto

et al. 2009

Funct Integr Genomics

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Three spikelets are formed at each rachis node of the cultivated barley (Hordeum vulgare ssp. vulgare) spike. In two-rowed barley, the central one is fertile and the two lateral ones are sterile, whereas in the six-rowed type, all three are fertile. This characteristic is determined by the allelic constitution at the six-rowed spike 1 (vrs1) locus on the long arm of chromosome 2H, with the recessive allele (vrs1) being responsible for the six-rowed phenotype. The Vrs1 (HvHox1) gene encodes a homeodomain-leucine zipper (HD-Zip) transcription factor. Here, we show that the Vrs1 gene evolved in the Poaceae via a duplication, with a second copy of the gene, HvHox2, present on the short arm of chromosome 2H. Micro-collinearity and polypeptide sequences were both well conserved between HvHox2 and its Poaceae orthologs, but Vrs1 is unique to the barley tribe. The Vrs1 gene product lacks a motif which is conserved among the HvHox2 orthologs. A phylogenetic analysis demonstrated that Vrs1 and HvHox2 must have diverged after the separation of Brachypodium distachyon from the Pooideae and suggests that Vrs1 arose following the duplication of HvHox2, and acquired its new function during the evolution of the barley tribe. HvHox2 was expressed in all organs examined but Vrs1 was predominantly expressed in immature inflorescence.Electronic supplementary materialThe online version of this article (doi:10.1007/s10142-009-0134-y) contains supplementary material, which is available to authorized users.

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“…Established interactions between MBF1 and members of the former family are FTZ-F1, Ad4BP (adrenal 4-binding protein; a human orthologue of FTZ-F1), and liver receptor homologue 1, liver X receptor α and PPARγ (peroxisome-proliferator-activated receptor γ ), non-steroid nuclear receptors, involved in lipid metabolism in humans [3,[5][6][7]25]. Known interaction partners belonging to the bZIP family include GCN4 (general control non-derepressible 4), CREB (cAMP-response-element-binding protein) and CREB1, ATF (activating transcription factor) 1, Jun and Fos, TDF (tracheae defective factor) and HaHB4 (Helianthus annuus homeobox-leucine zipper protein 4) [12,21,24,25,28,29]. Jun, Fos and ATF family members dimerize into homo-or hetero-dimers, all called AP-1 (activator protein 1).…”

Section: Transcription Activationmentioning

confidence: 99%

Role of multiprotein bridging factor 1 in archaea: bridging the domains?

Koning

Blombach

et al. 2009

Biochemical Society Transactions

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MBF1 (multiprotein bridging factor 1) is a highly conserved protein in archaea and eukaryotes. It was originally identified as a mediator of the eukaryotic transcription regulator BmFTZ-F1 (Bombyx mori regulator of fushi tarazu). MBF1 was demonstrated to enhance transcription by forming a bridge between distinct regulatory DNA-binding proteins and the TATA-box-binding protein. MBF1 consists of two parts: a C-terminal part that contains a highly conserved helix-turn-helix, and an N-terminal part that shows a clear divergence: in eukaryotes, it is a weakly conserved flexible domain, whereas, in archaea, it is a conserved zinc-ribbon domain. Although its function in archaea remains elusive, its function as a transcriptional co-activator has been deduced from thorough studies of several eukaryotic proteins, often indicating a role in stress response. In addition, MBF1 was found to influence translation fidelity in yeast. Genome context analysis of mbf1 in archaea revealed conserved clustering in the crenarchaeal branch together with genes generally involved in gene expression. It points to a role of MBF1 in transcription and/or translation. Experimental data are required to allow comparison of the archaeal MBF1 with its eukaryotic counterpart.

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Homeodomain-leucine Zipper Proteins Interact with a Plant Homologue of the Transcriptional Co-activator Multiprotein Bridging Factor 1

Cited by 9 publications

References 34 publications

Uncharacterized conserved motifs outside the HD-Zip domain in HD-Zip subfamily I transcription factors; a potential source of functional diversity

Uncharacterized conserved motifs outside the HD-Zip domain in HD-Zip subfamily I transcription factors; a potential source of functional diversity

Duplication of a well-conserved homeodomain-leucine zipper transcription factor gene in barley generates a copy with more specific functions

Role of multiprotein bridging factor 1 in archaea: bridging the domains?

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