Molecular interactions of BBX24 and BBX25 with HYH, HY5 HOMOLOG, to modulate<i>Arabidopsis</i>seedling development

Gangappa, Sreeramaiah N.; Holm, Magnus; Botto, Javier Francisco

doi:10.4161/psb.25208

Cited by 55 publications

(42 citation statements)

References 29 publications

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“…The B‐box domains play crucial roles in the interactions with other proteins. In Arabidopsis , AtBBX21 (Xu et al ., ), AtBBX22 (Datta et al ., ), AtBBX24 (Job et al ., ) and AtBBX25 (Gangappa et al ., ) physically interact with HY5, and three BBX proteins interact with HOMOLOG OF HY5 through B‐box domains (Gangappa et al ., ). A point mutation in the B‐box domain impedes the interaction with HY5 (Datta et al ., ).…”

Section: Discussionmentioning

confidence: 97%

BBX16, a B‐box protein, positively regulates light‐induced anthocyanin accumulation by activating MYB10 in red pear

Bai

Tao

Tang

et al. 2019

Plant Biotechnology Journal

236

180

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Summary The red coloration of pear (Pyrus pyrifolia) results from anthocyanin accumulation in the fruit peel. Light is required for anthocyanin biosynthesis in pear. A pear homolog of Arabidopsis thaliana BBX22, PpBBX16, was differentially expressed after fruits were removed from bags and may be involved in anthocyanin biosynthesis. Here, the expression and function of PpBBX16 were analysed. PpBBX16's expression was highly induced by white‐light irradiation, as was anthocyanin accumulation. PpBBX16's ectopic expression in Arabidopsis increased anthocyanin biosynthesis in the hypocotyls and tops of flower stalks. PpBBX16 was localized in the nucleus and showed trans‐activity in yeast cells. Although PpBBX16 could not directly bind to the promoter of PpMYB10 or PpCHS in yeast one‐hybrid assays, the complex of PpBBX16/PpHY5 strongly trans‐activated anthocyanin pathway genes in tobacco. PpBBX16's overexpression in pear calli enhanced the red coloration during light treatments. Additionally, PpBBX16's transient overexpression in pear peel increased anthocyanin accumulation, while virus‐induced gene silencing of PpBBX16 decreased anthocyanin accumulation. The expression patterns of pear BBX family members were analysed, and six additional BBX genes, which were differentially expressed during light‐induced anthocyanin biosynthesis, were identified. Thus, PpBBX16 is a positive regulator of light‐induced anthocyanin accumulation, but it could not directly induce the expression of the anthocyanin biosynthesis‐related genes by itself but needed PpHY5 to gain full function. Our work uncovered regulatory modes for PpBBX16 and suggested the potential functions of other pear BBX genes in the regulation of anthocyanin accumulation, thereby providing target genes for further studies on anthocyanin biosynthesis.

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Section: Discussionmentioning

confidence: 97%

BBX16, a B‐box protein, positively regulates light‐induced anthocyanin accumulation by activating MYB10 in red pear

Bai

Tao

Tang

et al. 2019

Plant Biotechnology Journal

236

180

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“…FHY3 binds to an FHY3 binding site and HY5 to an ACGT-containing element in the COP1 promoter, both of which seem to be required for the UV-B responsiveness of COP1 . Combinatorial regulation exerted by the interaction of other transcription factors with HY5/HYH is widely present, with negative or positive regulatory effects (Shin et al, 2007;Andronis et al, 2008;Holtan et al, 2011;Huang et al, 2012;Jiang et al, 2012;Singh et al, 2012;Gangappa et al, 2013aGangappa et al, , 2013bJing et al, 2013;Abbas et al, 2014). Moreover, HY5 interacts with the chromatin-remodeling factor PICKLE (PKL), recruiting PKL to promoters of target genes repressing the H3K27me3-repressive histone mark (Jing et al, 2013).…”

Section: Regulation Of the Hy5 Association With Chromatinmentioning

confidence: 99%

UV-B-Responsive Association of the Arabidopsis bZIP Transcription Factor ELONGATED HYPOCOTYL5 with Target Genes, Including Its Own Promoter

et al. 2014

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In plants subjected to UV-B radiation, responses are activated that minimize damage caused by UV-B. The bZIP transcription factor ELONGATED HYPOCOTYL5 (HY5) acts downstream of the UV-B photoreceptor UV RESISTANCE LOCUS8 (UVR8) and promotes UV-B-induced photomorphogenesis and acclimation. Expression of HY5 is induced by UV-B; however, the transcription factor(s) that regulate HY5 transcription in response to UV-B and the impact of UV-B on the association of HY5 with its target promoters are currently unclear. Here, we show that HY5 binding to the promoters of UV-B-responsive genes is enhanced by UV-B in a UVR8-dependent manner in Arabidopsis thaliana. In agreement, overexpression of REPRESSOR OF UV-B PHOTOMORPHOGENESIS2, a negative regulator of UVR8 function, blocks UV-B-responsive HY5 enrichment at target promoters. Moreover, we have identified a T/G-box in the HY5 promoter that is required for its UV-B responsiveness. We show that HY5 and its homolog HYH bind to the T/G HY5 -box cis-acting element and that they act redundantly in the induction of HY5 expression upon UV-B exposure. Therefore, HY5 is enriched at target promoters in response to UV-B in a UVR8 photoreceptor-dependent manner, and HY5 and HYH interact directly with a T/G-box cis-acting element of the HY5 promoter, mediating the transcriptional activation of HY5 in response to UV-B.

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“…Second, BBX24 physically 322 interacts with HY5 ( Fig. 2B) , and this interaction has previously been mapped to the 323 B-boxes of BBX24 and the bZIP domain of HY5 (Gangappa et al, 2013b). Lastly, cotransfection 324 experiments in Arabidopsis protoplasts have revealed that BBX24 and BBX25 inhibits the ability of HY5 to 325 promote BBX22 transcription, and this inhibition was dependent on the functionality of the B-box domains…”

mentioning

confidence: 99%

“…Nonetheless, the B-boxes of CO 402 are still likely to be essential for CO function as many isolated co mutants contain single amino acid 403 substitutions within the first or second B-box domain (Robson et al, 2001). Likewise, point mutations of 404 highly conserved residues within the first and second B-box of BBX24 and BBX21, likely disrupting the 405 structural integrity of each B-box domain, have indicated that the B-boxes of both these proteins are 406 essential both for their interaction with HY5 and their ability to regulate transcription (Datta et al, 2008;407 Gangappa et al, 2013a;Gangappa et al, 2013b). Thus, although the B-box domains appear to be 408 essential for the function of different groups of B-box containing proteins, our data, and that of others,…”

mentioning

confidence: 99%

Two B-Box Proteins Regulate Photomorphogenesis by Oppositely Modulating HY5 through their Diverse C-Terminal Domains

et al. 2018

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30Once sentence summary: The contrasting roles of BBX21 and BBX24 in photomorphogenesis arise 31 through their different C-terminal regions and how they alter HY5 function at the post-transcriptional level. 33 Abstract 34The Arabidopsis thaliana BBX family comprises several positive and negative regulators of 35 photomorphogenesis. BBX24, a member of BBX structural group IV, acts as a negative regulator of 36 photomorphogenesis, while another member from the same group, BBX21, is a positive regulator. The 37 molecular basis for the functional diversity shown by these related BBX family members is unknown. 38Using domain-swap lines, we show that the C-terminal regions of BBX24 and BBX21 specify their

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Molecular interactions of BBX24 and BBX25 with HYH, HY5 HOMOLOG, to modulateArabidopsisseedling development

Cited by 55 publications

References 29 publications

BBX16, a B‐box protein, positively regulates light‐induced anthocyanin accumulation by activating MYB10 in red pear

BBX16, a B‐box protein, positively regulates light‐induced anthocyanin accumulation by activating MYB10 in red pear

UV-B-Responsive Association of the Arabidopsis bZIP Transcription Factor ELONGATED HYPOCOTYL5 with Target Genes, Including Its Own Promoter

Two B-Box Proteins Regulate Photomorphogenesis by Oppositely Modulating HY5 through their Diverse C-Terminal Domains

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