A Clock- and Light-Regulated Gene That Links the Circadian Oscillator to LHCB Gene Expression

Xu, Yao; Johnson, Carl Hirschie

doi:10.1105/tpc.13.6.1411

Cited by 31 publications

(13 citation statements)

References 38 publications

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“…Very few examples of alternative splicing have been reported yet in plants (Kazan, 2003), and in these cases the splicing is often regulated in a tissue-, environmental-, or organellespecific manner (Lazar and Goodman, 2000;Kobayashi et al, 2001;Xu and Johnson, 2001;Shi et al, 2002). In our case, both mRNA seem to coexist in all the conditions tested but vary by their related levels.…”

Section: Discussionmentioning

confidence: 49%

AKINβγ Contributes to SnRK1 Heterotrimeric Complexes and Interacts with Two Proteins Implicated in Plant Pathogen Resistance through Its KIS/GBD Sequence

et al. 2006

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The sucrose nonfermenting-1 protein kinase (SNF1)/AMP-activated protein kinase subfamily plays a central role in metabolic responses to nutritional and environmental stresses. In yeast (Saccharomyces cerevisiae) and mammals, the b-and g-noncatalytic subunits are implicated in substrate specificity and subcellular localization, respectively, and regulation of the kinase activity. The atypical bg-subunit has been previously described in maize (Zea mays), presenting at its N-terminal end a sequence related to the KIS (kinase interacting sequence) domain specific to the b-subunits (Lumbreras et al., 2001). The existence of two components, SNF1-related protein kinase (SnRK1) complexes containing the bg-subunit and one SnRK1 kinase, had been proposed. In this work, we show that, despite its unusual features, the Arabidopsis (Arabidopsis thaliana) homolog AKINbg clearly interacts with AKINb-subunits in vitro and in vivo, suggesting its involvement in heterotrimeric complexes located in both cytoplasm and nucleus. Unexpectedly, a transcriptional analysis of AKINbg gene expression highlighted the implication of alternative splicing mechanisms in the regulation of AKINbg expression. A two-hybrid screen performed with AKINbg as bait, together with in planta bimolecular fluorescence complementation experiments, suggests the existence of interactions in the cytosol between AKINbg and two leucine-rich repeats related to pathogen resistance proteins. Interestingly, this interaction occurs through the truncated KIS domain that corresponds exactly to a GBD (glycogen-binding domain) recently described in mammals and yeast. A phylogenetic study suggests that AKINbg-related proteins are restricted to the plant kingdom. Altogether, these data suggest the existence of plant-specific SnRK1 trimeric complexes putatively involved in a plant-specific function such as plant-pathogen interactions.

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Section: Discussionmentioning

confidence: 49%

AKINβγ Contributes to SnRK1 Heterotrimeric Complexes and Interacts with Two Proteins Implicated in Plant Pathogen Resistance through Its KIS/GBD Sequence

et al. 2006

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“…7). In tobacco, such behavior involves the ZGT gene that links the circadian oscillator to LHCB expression (Xu and Johnson, 2001). One explanation of our data is that machinery such as ZGT exists to connect the expression of GmPPCK4 to the clock in soybean leaves but not in roots.…”

Section: Discussionmentioning

confidence: 80%

“…Since GmPPCK4 shows this pattern of expression, we analyzed the limited sequence information available for all four GmPPCK promoters. The GmPPCK4 promoter contains the sequence ATAATATCT, which differs from the evening element by just one base and includes the core seven-nucleotide sequence AATATCT noted by Xu and Johnson (2001). It also contains the sequence CACGTG, one version of the G-box core lightregulation motif (Chattopadhyay et al, 1998).…”

Section: Discussionmentioning

confidence: 99%

Roots, Cycles and Leaves. Expression of the Phosphoenolpyruvate Carboxylase Kinase Gene Family in Soybean

2004

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Phosphorylation of phosphoenolpyruvate carboxylase (PEPc; EC 4.1.1.31) plays an important role in the control of central metabolism of higher plants. This phosphorylation is controlled largely at the level of expression of PEPc kinase (PPCK) genes. We have analyzed the expression of both PPCK genes and the PEPC genes that encode PEPc in soybean (Glycine max). Soybean contains at least four PPCK genes. We report the genomic and cDNA sequences of these genes and demonstrate the function of the gene products by in vitro expression and enzyme assays. For two of these genes, GmPPCK2 and GmPPCK3, transcript abundance is highest in nodules and is markedly influenced by supply of photosynthate from the shoots. One gene, GmPPCK4, is under robust circadian control in leaves but not in roots. Its transcript abundance peaks in the latter stages of subjective day, and its promoter contains a sequence very similar to the evening element found in Arabidopsis genes expressed at this time. We report the expression patterns of five PEPC genes, including one encoding a bacterial-type PEPc lacking the phosphorylation site of the plant-type PEPcs. The PEPc expression patterns do not match those of any of the PPCK genes, arguing against the existence of specific PEPc-PPCK expression partners. The PEPC and PPCK gene families in soybean are significantly more complex than previously understood.

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“…However, transcription as measured with transcriptional LUC fusions has been shown to oscillate in DD for several genes in addition to CAT3, including CCR2 (Strayer et al, 2000), TOC1 (Strayer et al, 2000), EARLY FLOWERING 3 (Covington et al, 2001), PHYTOCHROME (PHY) A, PHYB, PHYD, PHYE, CRYPTOCHROME 1, and CRYPTO-CHROME 2 (Hall et al, 2001;Tó th et al, 2001). Moreover, overexpression of tobacco (Nicotiana tabacum) ZGT allows sustained oscillation of CAB2 transcription in extended dark (Xu and Johnson, 2001). …”

Section: Circadian Evening-specific Transcription Of the Cat3 Promotermentioning

confidence: 99%

Phase-Specific Circadian Clock Regulatory Elements in Arabidopsis

2002

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We have defined a minimal Arabidopsis CATALASE 3 (CAT3) promoter sufficient to drive evening-specific circadian transcription of a LUCIFERASE reporter gene. Deletion analysis and site-directed mutagenesis reveal a circadian response element, the evening element (EE: AAAATATCT), that is necessary for evening-specific transcription. The EE differs only by a single base pair from the CIRCADIAN CLOCK ASSOCIATED 1-binding site (CBS: AAAAAATCT), which is important for morning-specific transcription. We tested the hypothesis that the EE and the CBS specify circadian phase by site-directed mutagenesis to convert the CAT3 EE into a CBS. Changing the CAT3 EE to a CBS changes the phase of peak transcription from the evening to the morning in continuous dark and in light-dark cycles, consistent with the specification of phase by the single base pair that distinguishes these elements. However, rhythmicity of the CBS-containing CAT3 promoter is dramatically compromised in continuous light. Thus, we conclude that additional information normally provided in the context of a morning-specific promoter is necessary for full circadian activity of the CBS.The circadian clock enables an organism to specifically partition aspects of its biology to precise times over the day (Dunlap, 1999). Although the circadian clock is, by definition, endogenous and continues to run in the absence of external time cues, environmental stimuli such as light and temperature act to entrain the internal processes of an organism both to the exact external daily period and in a defined relationship, or phase angle, to the diurnal cycle. For example, in Arabidopsis, light and temperature information are integrated to partition physiological activities such as circadian-regulated leaf movement, stomatal opening, and gene expression to distinct times of day or phases (McClung et al., 2002).A central theme that has emerged in circadian biology is that the core oscillator is composed of a negative feedback loop grounded in positive and negative transcriptional regulation (Dunlap, 1999). It has recently been demonstrated that the Arabidopsis circadian clock entails such a transcriptional feedback loop (Alabadí et al., 2001) that includes at least three components: TIMING OF CAB EXPRESSION 1 (TOC1; also called Arabidopsis PSEUDO-RESPONSE REGULATOR 1, APRR1; Millar et al., 1995;, CIRCADIAN CLOCK ASSOCIATED 1 (CCA1; Wang and Tobin, 1998), and LATE ELON-GATED HYPOCOTYL (LHY; Schaffer et al., 1998).CCA1 and LHY are single-Myb domain transcription factors, and DNA-binding activity of CCA1 to a CCA1-binding site (CBS: AAAAATCT) has been characterized (Wang et al., 1997). The hypothesized role of TOC1 as a transcription factor is based on similarity to CONSTANS, although DNA binding by TOC1 has not been experimentally established (Strayer et al., 2000). However, TOC1 (APRR1) has been shown to bind to PHYTOCHROME-INTERACTING FACTOR 3 (PIF3), a Myc-related basic helix-loop-helix transcription factor, and to the related PIF3-LIKE 1 (PIL1; Makino et al., 2002). Expression o...

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A Clock- and Light-Regulated Gene That Links the Circadian Oscillator to LHCB Gene Expression

Cited by 31 publications

References 38 publications

AKINβγ Contributes to SnRK1 Heterotrimeric Complexes and Interacts with Two Proteins Implicated in Plant Pathogen Resistance through Its KIS/GBD Sequence

AKINβγ Contributes to SnRK1 Heterotrimeric Complexes and Interacts with Two Proteins Implicated in Plant Pathogen Resistance through Its KIS/GBD Sequence

Roots, Cycles and Leaves. Expression of the Phosphoenolpyruvate Carboxylase Kinase Gene Family in Soybean

Phase-Specific Circadian Clock Regulatory Elements in Arabidopsis

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