A Novel Family of Calmodulin-binding Transcription Activators in Multicellular Organisms

Bouché, Nicolas; Scharlat, Ariel; Snedden, Wayne A.; Bouchez, David; Fromm, Hillel

doi:10.1074/jbc.m200268200

Cited by 281 publications

(317 citation statements)

References 61 publications

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“…This may reflect differences among organisms with respect to the cellular levels of NADK substrates. The high affinity of Arabidopsis NADK for CaM (S 0.5 of 2.2 nM) is consistent with reports on other plant NADKs (Harmon et al, 1984;Lee et al, 1997;Delumeau et al, 2000) and other plant CaM-binding proteins (Snedden et al, 1996;Bouche et al, 2002;Zhang et al, 2002;Chandok et al, 2003). Similarly, the S 0.5 value for Ca 21 (0.8 mM) suggests stimuli that elevate Ca 21 from resting levels in vivo may elicit a CaM-modulated NADK response.…”

Section: Discussionsupporting

confidence: 88%

Cloning and Characterization of Two NAD Kinases from Arabidopsis. Identification of a Calmodulin Binding Isoform

et al. 2004

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NAD kinase (NADK; ATP:NAD 2#-phosphotransferase, EC 2.7.1.23), an enzyme found in both prokaryotes and eukaryotes, generates the important pyridine nucleotide NADP from substrates ATP and NAD. The role of NADKs in plants is poorly understood, and cDNAs encoding plant NADKs have not previously been described to our knowledge. We have cloned two cDNAs from Arabidopsis predicted to encode NADK isoforms, designated NADK1 and NADK2, respectively. Expressed as recombinant proteins in bacteria, both NADK1 and NADK2 were catalytically active, thereby confirming their identity as NADKs. Transcripts for both isoforms were detected in all tissues examined and throughout development. Although the predicted catalytic regions for NADK1 and NADK2 show sequence similarity to NADKs from other organisms, NADK2 possesses a large N-terminal extension that appears to be unique to plants. Using recombinant glutathione-S-transferase fusion proteins and calmodulin (CaM)-affinity chromatography, we delineated a Ca 21 -dependent CaM-binding domain to a 45-residue region within the N-terminal extension of NADK2. Although recombinant NADK2 was not responsive to CaM in vitro, immunoblot analysis suggests that native NADK2 is a CaM-binding protein. In Arabidopsis crude extracts, CaMdependent NADK activity was much greater than CaM-independent activity throughout development, particularly in young seedlings. A native CaM-dependent NADK was partially purified from Arabidopsis seedlings (K m NAD 5 0.20 mM, K m Mg 21 2ATP 5 0.17 mM). The enzyme was fully activated by conserved CaM (S 0.5 5 2.2 nM) in the presence of calcium but displayed differential responsiveness to eight CaM-like Arabidopsis proteins. Possible roles for NADKs in plants are discussed in light of our observations.

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Section: Discussionsupporting

confidence: 88%

Cloning and Characterization of Two NAD Kinases from Arabidopsis. Identification of a Calmodulin Binding Isoform

et al. 2004

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“…If a protein fragment contained a transactivation domain, it would be expected to autoactivate and turn on the appropriate reporter genes in yeast, as illustrated earlier (35,36). We had previously shown that full-length NRL activated rhodopsin promoter, whereas DD10, a naturally occurring variant of NRL that lacked most of the proline-and serine-rich region, did not (20).…”

Section: Identification Of Nrl Domains Capable Of Transactivationmentioning

confidence: 97%

The Minimal Transactivation Domain of the Basic Motif-Leucine Zipper Transcription Factor NRL Interacts with TATA-binding Protein

Friedman

Khanna

Swain

et al. 2004

Journal of Biological Chemistry

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The basic motif-leucine zipper (bZIP) transcription factor NRL controls the expression of rhodopsin and other phototransduction genes and is a key mediator of photoreceptor differentiation. To delineate the molecular mechanisms underlying transcriptional initiation of rod-specific genes, we characterized different regions of the NRL protein using yeast-based autoactivation assays. We identified 35 amino acid residues in the proline-and serine-rich N-terminal region (called minimal transactivation domain, MTD), which, when combined with LexA or Gal4 DNA binding domains, exhibited activation of target promoters. Because this domain is conserved in all proteins of the large Maf family, we hypothesized that NRL-MTD played an important role in assembling the transcription initiation complex. Our studies showed that the NRL protein, including the MTD, interacted with full-length or the C-terminal domain of TATA-binding protein (TBP) in vitro. NRL and TBP could be co-immunoprecipitated from bovine retinal nuclear extract. TBP was also part of c-Maf and MafA (two other large Maf proteins)-containing complex(es) in vivo. Our data suggest that the function of NRL-MTD is to activate transcription by recruiting or stabilizing TBP (and consequently other components of the general transcription complex) at the promoter of target genes, and a similar function may be attributed to other bZIP proteins of the large Maf family.

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“…This cis-element is activated by the ABRE-binding Factor (ABF) family of bZIP transcription factors (Choi et al, 2000). The second sequence, ACGCGT, is similar to the ABRE but instead has the core sequence CGCG, which is the binding site for CAMTAs (Bouché et al, 2002); we will refer to this site as the "CAM box." The two other alignments from RSAT ( Figures 2C and 2D) also revealed sequences that we identified as previously described cis-regulatory elements.…”

Section: Imposed [Ca 2+ ] C Elevations Are Capable Of Inducing Signifmentioning

confidence: 99%

Transcriptomic Analysis Reveals Calcium Regulation of Specific Promoter Motifs inArabidopsis

et al. 2011

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Increases in intracellular calcium concentration ([Ca 2+ ] c ) mediate plant responses to stress by regulating the expression of genes encoding proteins that confer tolerance. Several plant stress genes have previously been shown to be calciumregulated, and in one case, a specific promoter motif Abscisic Acid Responsive-Element (ABRE) has been found to be regulated by calcium. A comprehensive survey of the Arabidopsis thaliana transcriptome for calcium-regulated promoter motifs was performed by measuring the expression of genes in Arabidopsis seedlings responding to three calcium elevations of different characteristics, using full genome microarray analysis. This work revealed a total of 269 genes upregulated by [Ca 2+ ] c in Arabidopsis. Bioinformatic analysis strongly indicated that at least four promoter motifs were [Ca 2+ ] c -regulated in planta. We confirmed this finding by expressing in plants chimeric gene constructs controlled exclusively by these cis-elements and by testing the necessity and sufficiency of calcium for their expression. Our data reveal that the C-Repeat/Drought-Responsive Element, Site II, and CAM box (along with the previously identified ABRE) promoter motifs are calcium-regulated. The identification of these promoter elements targeted by the second messenger intracellular calcium has implications for plant signaling in response to a variety of stimuli, including cold, drought, and biotic stress.

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A Novel Family of Calmodulin-binding Transcription Activators in Multicellular Organisms

Cited by 281 publications

References 61 publications

Cloning and Characterization of Two NAD Kinases from Arabidopsis. Identification of a Calmodulin Binding Isoform

Cloning and Characterization of Two NAD Kinases from Arabidopsis. Identification of a Calmodulin Binding Isoform

The Minimal Transactivation Domain of the Basic Motif-Leucine Zipper Transcription Factor NRL Interacts with TATA-binding Protein

Transcriptomic Analysis Reveals Calcium Regulation of Specific Promoter Motifs inArabidopsis

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