GIGANTEA is a co-chaperone which facilitates maturation of ZEITLUPE in the Arabidopsis circadian clock

Cha, Joon‐Yung; Kim, Jeong-Sik; Kim, Taesung; Zeng, Qingning; Wang, Lei; Lee, Sang Yeol; Kim, Woe‐Yeon; Somers, David E.

doi:10.1038/s41467-016-0014-9

Cited by 115 publications

(127 citation statements)

References 68 publications

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“…In Arabidopsis , GI is a key component of this transduction pathway. It has been suggested that GI acts as a scaffolding protein that orchestrates other protein interactions (Imaizumi et al ., ), for instance by indirectly mediating the degradation of transcriptional repressors (Mas et al ., ; Kiba et al ., ; Sawa et al ., ) and by providing co‐chaperone activity (Cha et al ., ). PttGIRNAi trees are dwarfed and they terminate growth and induce bud set even under LD 23 h conditions, suggesting that PttGI expression is absolutely required in order to maintain vegetative growth and prevent growth cessation on long days (Fig.…”

Section: Discussionmentioning

confidence: 97%

“…GIGANTEA ( GI ) is a unique plant‐specific nuclear protein involved in numerous facets of plant physiology and development, including the control of flowering time, hypocotyl elongation, circadian period, salt tolerance and other processes (Huq et al ., ; Sawa et al ., ; Dalchau et al ., ; Kim et al ., ; Park et al ., ; Mishra & Panigrahi, ; Cha et al ., ). In Arabidopsis , GI regulates photoperiodic flowering time via different pathways (Jung et al ., ; Sawa et al ., ; Sawa & Kay, ; Song et al ., , ).…”

Section: Introductionmentioning

confidence: 97%

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GIGANTEA‐like genes control seasonal growth cessation in Populus

et al. 2018

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Summary Survival of trees growing in temperate zones requires cycling between active growth and dormancy. This involves growth cessation in the autumn triggered by a photoperiod shorter than the critical day length. Variations in GIGANTEA (GI)‐like genes have been associated with phenology in a range of different tree species, but characterization of the functions of these genes in the process is still lacking. We describe the identification of the Populus orthologs of GI and their critical role in short‐day‐induced growth cessation. Using ectopic expression and silencing, gene expression analysis, protein interaction and chromatin immunoprecipitation experiments, we show that PttGIs are likely to act in a complex with PttFKF1s (FLAVIN‐BINDING, KELCH REPEAT, F‐BOX 1) and PttCDFs (CYCLING DOF FACTOR) to control the expression of PttFT2, the key gene regulating short‐day‐induced growth cessation in Populus. In contrast to Arabidopsis, in which the GI‐CONSTANS (CO)‐FLOWERING LOCUS T (FT) regulon is a crucial day‐length sensor for flowering time, our study suggests that, in Populus, PttCO‐independent regulation of PttFT2 by PttGI is more important in the photoperiodic control of growth cessation and bud set.

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 97%

GIGANTEA‐like genes control seasonal growth cessation in Populus

et al. 2018

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“…However, the elf3 – ztl double mutant showed that ELF3 and ZTL have additive effects on the clock (Kim et al, ). As GI controls the HSP90 mediated stabilisation of ZTL protein (Cha et al, ; Kim et al, ), ZTL protein then causes protein depletion of TOC1 via ubiquitination (Kim et al, ). ELF3 interacts as a substrate adaptor for COP1 (an E3 ubiquitin ligase) to bind to and degrade GI protein, as a light input signal and indicator of day length in response to CRY2 (Yu et al, ).…”

Section: Ztl Family: Blue Light Absorbing With Action Under Red Lightmentioning

confidence: 99%

“…These are proposed to result from the binding of GI to maintain the stability of ZTL. ZTL protein folding is chaperoned by HSP90 (Kim et al, 2011), GI binds to the ZTL-HSP90 complex to ensure specificity of protein folding (Cha et al, 2017;Kim et al, 2011). Interactions between ZTL and GI are enhanced by blue light through the LOV domain in ZTL (Kim et al, 2007).…”

Section: Ztl Family: Blue Light Absorbing With Action Under Red Ligmentioning

confidence: 99%

Shining a light on the Arabidopsis circadian clock

Oakenfull

Davis

2017

Plant Cell & Environment

112

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The circadian clock provides essential timing information to ensure optimal growth to prevailing external environmental conditions. A major time-setting mechanism (zeitgeber) in clock synchronization is light. Differing light wavelengths, intensities, and photoperiodic duration are processed for the clock-setting mechanism. Many studies on light-input pathways to the clock have focused on Arabidopsis thaliana. Photoreceptors are specific chromic proteins that detect light signals and transmit this information to the central circadian oscillator through a number of different signalling mechanisms. The most well-characterized clock-mediating photoreceptors are cryptochromes and phytochromes, detecting blue, red, and far-red wavelengths of light. Ultraviolet and shaded light are also processed signals to the oscillator. Notably, the clock reciprocally generates rhythms of photoreceptor action leading to so-called gating of light responses. Intermediate proteins, such as Phytochrome interacting factors (PIFs), constitutive photomorphogenic 1 (COP1) and EARLY FLOWERING 3 (ELF3), have been established in signalling pathways downstream of photoreceptor activation. However, the precise details for these signalling mechanisms are not fully established. This review highlights both historical and recent efforts made to understand overall light input to the oscillator, first looking at how each wavelength of light is detected, this is then related to known input mechanisms and their interactions.

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“…A further, critical factor is the slow degradation rate of the transcriptional repressors, which mathematical analysis has long identified and experiments confirm as key to timing (Gerard et al 2009, Ruoff et al 2005. Regulated protein degradation is also crucial to plant circadian 7 GI's role in the clock is mediated at the biochemical level by co-chaperone activity, which involves binding to HSP90 and appears to stabilize ZTL (Kim et al, 2011;Cha et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Time-resolved Interaction Proteomics of the Putative Scaffold Protein GIGANTEA inArabidopsis thaliana

Krahmer

Goralogia

Kubota

et al. 2017

Preprint

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SummaryThe large, plant-specific protein GIGANTEA (GI) is involved in many physiological processes, mediating rhythmic, post-translational regulation in part through circadian and light regulation of GI RNA expression. GI binds several proteins implicated in the circadian clock, the control of photoperiodic flowering, and abiotic stress responses, and has co-chaperone activity. By extension, further interaction partners might mediate the less well-understood roles of GI but the number and rhythmicity of these interactors is unknown. Here, we seek potential interactors in a time-specific manner, using quantitative proteomics from a time series study of transgenic Arabidopsis thaliana plants constitutively expressing an epitope-tagged GI protein. Previously-identified, direct and indirect interactors of GI were detected but no further F-box proteins related to known GI partners ZTL/FKF1/LKP2. The predominantly non-rhythmic, interacting proteins were implicated in protein folding or degradation, metabolism and chromatin modification, including a small set of partners shared with other clock-related proteins. A transcription factor homologue that we name CYCLING DOF FACTOR 6 (CDF6) was shown to interact both with GI and the ZTL/FKF1/LKP2 proteins and to control photoperiodic flowering. Our results indicate the biochemical pathways, beyond circadian and flowering regulation, that might be affected by GIGANTEA’s rhythmic, post-translational control.Significance StatementSignificance statement of up to two sentences of no more than 75 words total;The GIGANTEA protein of Arabidopsis was known for circadian and flowering functions, mediated by the FKF1/LKP2/ZTL family of GI-interacting, F-box proteins, then for a co-chaperone activity of unknown scope. We performed time-resolved, interaction proteomics, identifying CDF6 (At1g26790) as a morning-specific GI interactor that controls flowering time. Unlike FKF1 and CDF proteins, most of the 240 candidate partners were not rhythmically enriched. They link GI to proteostasis and metabolic functions that might mediate GI’s physiological functions.

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GIGANTEA is a co-chaperone which facilitates maturation of ZEITLUPE in the Arabidopsis circadian clock

Cited by 115 publications

References 68 publications

GIGANTEA‐like genes control seasonal growth cessation in Populus

GIGANTEA‐like genes control seasonal growth cessation in Populus

Shining a light on the Arabidopsis circadian clock

Time-resolved Interaction Proteomics of the Putative Scaffold Protein GIGANTEA inArabidopsis thaliana

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