The Arabidopsis BELL1 and KNOX TALE Homeodomain Proteins Interact through a Domain Conserved between Plants and Animals

Bellaoui, Mohammed; Pidkowich, Mark S.; Samach, Alon; Kushalappa, Kumuda; Kohalmi, Susanne E.; Modrušan, Zora; Crosby, William L.; Haughn, George W.

doi:10.2307/3871587

Cited by 9 publications

(18 citation statements)

References 13 publications

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“…This observation is also supported by the fact that [ 35 S]Met-KIP selectively binds to STM, the KN1 ortholog, with a higher affinity than to KNAT1 or KNAT2 in Arabidopsis ligand blot assays (unpublished data). In Arabidopsis, BEL1 may also selectively bind to a subset of KNOX proteins (33). Taken together, these studies strongly suggest that the interaction of KNOX and BELL proteins depends on not only overlapping expression patterns but also on the ability of these proteins to physically associate with one another.…”

Section: Discussionmentioning

confidence: 77%

“…Although KNOX-BELL interactions have been described in Arabidopsis (33) and barley (34), the biochemical function of this interaction was not addressed. Because DNA recognition and binding are initial steps in gene regulation, we examined how the interaction of KN1 and KIP affects DNA binding.…”

Section: Discussionmentioning

confidence: 99%

“…1E) strongly suggests that the function of this domain is to interact with the MEINOX domain in KNOX proteins. In fact, the M1 and M2 regions in BEL1, also known as SKY and BELL domains, respectively, were shown to interact with KNAT1 and KNAT3 (33). Therefore, we refer to this region as MID.…”

Section: The Meinox Domain Of Kn1 Interacts With a Tale Hd Protein Inmentioning

confidence: 99%

“…Lastly, this interaction is important for protein stability (27,28) and in Drosophila, hth and exd mutants have strikingly similar phenotypes (22,24,(29)(30)(31). Taken together, these studies strongly suggest that the MEIS-PBX heterodimer can be described as a single functional unit (32).Recently two-hybrid studies have indicated that KNOX proteins interact with BEL1-like (BELL) proteins, another class of TALE HD proteins found in plants (33,34). The mRNA expression patterns of KNOX and BELL proteins overlap in meristems, indicating that they may potentially interact in vivo.…”

mentioning

confidence: 96%

“…Recently two-hybrid studies have indicated that KNOX proteins interact with BEL1-like (BELL) proteins, another class of TALE HD proteins found in plants (33,34). The mRNA expression patterns of KNOX and BELL proteins overlap in meristems, indicating that they may potentially interact in vivo.…”

mentioning

confidence: 99%

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Selective interaction of plant homeodomain proteins mediates high DNA-binding affinity

Smith

Boschke

Hake

2002

Proc. Natl. Acad. Sci. U.S.A.

160

166

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Understanding molecular mechanisms that control cell fate in the shoot apical meristem is a fundamental question in plant development. Genetic and molecular studies demonstrate that maize KNOTTED1 (KN1) of the TALE (3-aa acid loop extension) class of homeodomain (HD) proteins is involved in shoot apical meristem function. We show that KN1 interacts with knotted interacting protein (KIP), a BEL1-like TALE HD protein. Interaction between KN1 and KIP is mediated by conserved domains in the N termini of both proteins. The KN1 DNA-binding sequence, TGACAG(G͞C)T, was biochemically identified, and in vitro DNA-binding assays show that individually KN1 and the HD of KIP bind specifically to this motif with low affinity. The KN1-KIP complex, however, binds specifically to this DNA-binding motif with high affinity, indicating that the association of KN1 and KIP may function in transcriptional regulation. In plants, development of the aerial shoot is controlled by a group of cells in the shoot apex called the shoot apical meristem (SAM). The SAM is the site where organogenesis is initiated and from which leaves, flowers, or other determinate structures are produced. Because plant development is a continuous process, the SAM must balance the process of differentiation and maintenance to allow growth.Maize knotted1 (kn1) and the Arabidopsis ortholog SHOOT-MERISTEMLESS (STM) are members of the knox family of genes that are required for SAM function (1). The expression of kn1 and STM is restricted to the indeterminate cells of the SAM. Moreover, this pattern of expression is excluded from the zone of the SAM that gives rise to organs (2, 3). Loss-of-function mutations in kn1 and STM produce a shootless phenotype, where the SAM prematurely terminates after initiating cotyledons, demonstrating that kn1 and STM function in meristem maintenance (3-5). In backgrounds where some shoot formation occurs, organ production is reduced, indicating that vegetative and inflorescence meristems are compromised (4,(6)(7)(8). In addition to maintenance functions, class 1 knox genes, including kn1, are capable of respecifying cell fates when ectopically expressed in the leaf (1). Studies that support this hypothesis come from analysis of dominant mutations in the maize knox genes, kn1, rough sheath1 (rs1), liguleless3 (lg3), and gnarley1 (gn1) (9-12). Each of these phenotypes is caused by ectopic leaf expression, resulting in proximal leaf cell identities transposed distally into the blade (1, 13).The knox gene family was the first group of plant genes identified that encodes homeodomain (HD) proteins (14). In animals, HD-containing proteins function as transcription factors that are important regulators of animal cell fate and development (15). The HD is a conserved structure that contains three ␣ helices, and a sequence motif in the third helix recognizes and binds to the appropriate DNA sequence (15). Amino acid sequence comparison studies have subdivided the HD family into two classes of proteins: the typical HD class and the TALE (3-aa loop...

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Section: Discussionmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Section: The Meinox Domain Of Kn1 Interacts With a Tale Hd Protein Inmentioning

confidence: 99%

mentioning

confidence: 96%

mentioning

confidence: 99%

See 3 more Smart Citations

Selective interaction of plant homeodomain proteins mediates high DNA-binding affinity

Smith

Boschke

Hake

2002

Proc. Natl. Acad. Sci. U.S.A.

160

166

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Natural Variation in Leaf Morphology Results from Mutation of a Novel KNOX Gene

Kimura¹,

Koenig²,

Kang³

et al. 2008

Current Biology

184

183

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Striking diversity in size, arrangement, and complexity of leaves can sometimes be seen in closely related species. One such variation is found between wild tomato species collected by Charles Darwin from the Galapagos Islands [1-5]. Here, we show that a single-nucleotide deletion in the promoter of the PETROSELINUM (PTS) [3] gene upregulates the gene product in leaves and is responsible for the natural variation in leaf shape in the Galapagean tomatoes. PTS encodes a novel KNOTTED1-LIKE HOMEOBOX (KNOX) gene that lacks a homeodomain. We also showed that the tomato classical mutant bipinnata (bip) [6], which recapitulates the Pts phenotype, results from the loss of function of a BEL-LIKE HOMEODOMAIN (BELL) gene, BIP. We used bimolecular fluorescence complementation and two-hybrid competition assays to show that PTS represses KNOX1 protein interactions with BIP, as well as subsequent nuclear localization of this transcriptional complex. We suggest that natural variation in leaf shape can be created with a rheostat-like mechanism that alters the KNOX1 protein interaction network specifically during leaf development. This subtle change in interaction between transcription factors leaves essential KNOX1 function in the shoot apical meristem intact and appears to be a facile way to alter leaf morphology during evolution.

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A central role of Arabidopsis thaliana ovate family proteins in networking and subcellular localization of 3-aa loop extension homeodomain proteins

Hackbusch¹,

Richter

Müller

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

258

285

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The organization of living cells is based on networks of interacting molecules. Systematic analysis of protein interactions of 3-aa loop extension (TALE) homeodomain proteins, fundamental regulators of plant meristem function and leaf development, revealed a highly connected, complex network. The network includes nine members of Arabidopsis thaliana ovate family proteins (AtOFPs), a plant-specific protein family, indicating a close functional connection to TALE homeodomain proteins. Evidence is provided that AtOFP1 is an essential pleiotropic developmental regulator. At-OFP1 and AtOFP5 are shown to associate with the cytoskeleton and to regulate subcellular localization of TALE homeodomain proteins, suggesting a previously unrecognized control mechanism in plant development.cytoskeleton ͉ network modules ͉ protein-protein interactions ͉ BELL proteins ͉ KNOX proteins

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The Arabidopsis BELL1 and KNOX TALE Homeodomain Proteins Interact through a Domain Conserved between Plants and Animals

Cited by 9 publications

References 13 publications

Selective interaction of plant homeodomain proteins mediates high DNA-binding affinity

Selective interaction of plant homeodomain proteins mediates high DNA-binding affinity

Natural Variation in Leaf Morphology Results from Mutation of a Novel KNOX Gene

A central role of Arabidopsis thaliana ovate family proteins in networking and subcellular localization of 3-aa loop extension homeodomain proteins

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