Nitrogen regulates CRY1 phosphorylation and circadian clock input pathways

Zhou, Yang-Hong; Zhang, Zhongwei; Zheng, Chong; Yuan, Shu

doi:10.1080/15592324.2016.1219830

Cited by 6 publications

(1 citation statement)

References 24 publications

(35 reference statements)

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“…Flowering, a crucial developmental switch from the vegetative to the reproductive stage, is regulated by multiple post-translational modifications, including reversible protein phosphorylation (Ogiso et al, 2010;Kim and Sung, 2012;Mulekar and Huq, 2014;Zhou et al, 2016). A wide range of protein kinases have been identified to be responsible for phosphorylating key factors of the internal and external flowering pathways, such as hormones, the sugar metabolic pathway, light signaling and the circadian clock (Oh et al, 2009;Shi et al, 2014;Jeong et al, 2015;Wang et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

MLK4‐mediated phosphorylation of histone H3T3 promotes flowering by transcriptional silencing of FLC/MAF in Arabidopsis thaliana

et al. 2021

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Casein kinase I (CK1), a ubiquitous Ser/Thr protein kinase in eukaryotes, plays a critical role in higher plant flowering. Arabidopsis CK1 family member MUT9-LIKE KINASEs, such as MLK1 and MLK3, have been shown to phosphorylate histone H3 at threonine 3 (H3T3), an evolutionarily conserved residue, and the modification is associated with the transcriptional repression of euchromatic and heterochromatic loci. This study demonstrates that mlk4-3, a T-DNA insertion mutant of MLK4, flowered late, and that overexpression of MLK4 caused early flowering. The nuclear protein MLK4 phosphorylated histone H3T3 both in vitro and in vivo, and this catalytic activity required the conserved lysine residue K175. mutation of MLK4 at K175 failed to restore the level of phosphorylated H3T3 (H3T3ph) or to complement the phenotypic defects of mlk4-3. The FLC/MAF-clade genes, including FLC, MAF4 and MAF5, were significantly upregulated in mlk4-3. The double mutant mlk4-3 flc-3 flowered earlier than mlk4-3, suggesting that functional FLC is crucial for flowering repression in mlk4-3. Chromatin immunoprecipitation assays showed that MLK4 bound to FLC/ MAF chromatin and that H3T3ph occupancy at the promoter of FLC/MAF was negatively associated with its transcriptional level. In accordance, H3T3ph accumulated at FLC/MAF in 35S::MLK4/mlk4-3 but diminished in 35S::MLK4(K175R)/mlk4-3 plants. Moreover, the amount of RNA Pol II deposited at FLC/MAF was clearly enriched in mlk4-3 relative to the wild type. Therefore, MLK4-dependent phosphorylation of H3T3 contributes to accelerating flowering by repressing the transcription of negative flowering regulator FLC/MAF. This study sheds light on the delicate control of flowering by the plant-specific CK1, MLK4, via post-translational modification of histone H3.

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