Browsing by Author "Yadav, Vandana"

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A basic helix-loop-helix transcription factor in Arabidopsis, MYC2, acts as a repressor of of blue light-mediate photomorphogenic growth
(American Society of Plant Biologists, 2005) Yadav, Vandana; Mallappa, Chandrashekara; Gangappa, Sreeramaiah N.; Bhatia, Shikha; Chattopadhyay, Sudip
This work is supported by Department of Biotechnology and Department of Science and Technology grants to S.C. V.Y., C.M., and S.N.G. are recipients of Council of Scientific and Industrial Research fellowships from the government of India.
A basic leucine zipper transcription factor, G-box-binding factor 1, regulates blue light-mediated photomorphogenic growth in Arabidopsis
(The American Society for Biochemistry and Molecular Biology, Inc., 2006) Mallappa, Chandrashekara; Yadav, Vandana; Negi, Prem; Chattopadhyay, Sudip
Several transcriptional regulators have been identified and demonstrated to play either positive or negative regulatory roles in seedling development. However, the regulatory coordination between hypocotyl elongation and cotyledon expansion during early seedling development in plants remains unknown. We report the identification of a Z-box binding factor (ZBF2) and its functional characterization in cryptochrome-mediated blue light signaling. ZBF2 encodes a G-box binding factor (GBF1), which is a basic leucine zipper transcription factor. Our DNA- protein interaction studies reveal that ZBF2/GBF1 also interacts with the Z-box light-responsive element of light-regulated promoters. Genetic analyses of gbf1 mutants and overexpression studies suggest that GBF1 acts as a repressor of blue light-mediated inhibition in hypocotyl elongation, however, it acts as a positive regulator of cotyledon expansion during photomorphogenic growth. Furthermore, whereas GBF1 acts as a positive regulator of lateral root formation, it differentially regulates the expression of light-inducible genes. Taken together, these results demonstrate that GBF1 is a unique transcriptional regulator of photomorphogenesis in blue light.
Light mediated regulation defines a minimal promoter region of TOP2
(Oxford University Press, 2003) Hettiarachchi, G. H. C. M.; Yadav, Vandana; Reddy, M. K.; Chattopadhyay, Sudip; Sopory, Sudhir K.
Light signaling has been demonstrated to be an important factor for plant growth and development; however, its role in the regulation of DNA replication and cell cycle has just started to be unraveled. In this work, we have demonstrated that the TOP2 promoter of Pisum sativum (pea) is activated by a broad spectrum of light including far-red light (FR), red light (RL) and blue light (BL). Deletion analyses of the TOP2 promoter in transformed plants, Arabidopsis thaliana and Nicotiana tobaccum (tobacco), de®ne a minimal promoter region that is induced by RL, FR and BL, and is essential and suficient for light-mediated activation. The minimal promoter of TOP2 follows the phytochromemediated low- ̄uence response similar to complex light regulated promoters. DNA±protein interaction studies reveal the presence of a DNA binding activity speci®c to a 106 bp region of the minimal promoter that is crucial for light-mediated activation. These results altogether indicate a direct involvement of light signaling in the regulation of expression of TOP2, one of the components of the DNA replication/cell cycle machinery.
Light regulated modulation of Z-box containing promoters by photoreceptor and downstream regulatory components, COP1 and HY5 in Arabidopsis thaliana
(Wiley-Blackwell, 2002) Yadav, Vandana; Kundu, Snehangshu; Chattopadhyay, Debasis; Negi, Prem; Wei, Ning; Deng, Xing-Wang; Chattopadhyay, Sudip
The Z-box is one of the light-responsive elements (LREs) found in the promoters of light inducible genes. We have studied the light responsive characteristics of Z-box containing synthetic as well as native promoters. We show that promoters with Z-box as a single LRE or paired with another LRE can respond to a broad spectrum of light. The response is primarily mediated by phyA, phyB and CRY1 photoreceptors at their respective wavelengths of light. We have demonstrated that CAB1 and Z-GATA containing promoters are down-regulated in hy5 mutants in the light. On the other hand, a promoter with Z-box alone is down-regulated in hy5 mutants both in dark and in light conditions, suggesting involvement of a similar regulatory system in the regulation of the promoter in two distinct developmental pathways: skotomorphogenesis and photomorphogenesis. Furthermore, similar to the CAB1 promoter, a Z-GATA containing promoter is derepressed in cop1 mutants in the dark. DNA±protein interaction studies reveal the presence of a DNA-binding activity that is speci®c to Z-box. These results provide insights into the regulation of the Z-box LRE mediated by various light signaling components.
The regulation of the Z- and G-box containing promoters by light signaling components, SPA1 and MYC2, in Arabidopsis
(PLOS, 2013) Gangappa, Sreeramaiah N.; Maurya, Jay P.; Yadav, Vandana; Chattopadhyay, Sudip
Although many transcription factors and regulatory proteins have been identified and functionally characterized in light signaling pathways, photoperception to transcription remains largely fragmented. The Z-box is one of the LREs (Light responsive elements) that plays important role in the regulation of transcription during light-controlled Arabidopsis seedling development. The involvement of photoreceptors in the modulation of the activity of the Z-box containing promoters has been demonstrated. However, the role of downstream signaling components such as SPA1 and MYC2/ZBF1, which are functionally interrelated, remains unknown. In this study, we have investigated the regulation of the Z-box containing synthetic and native promoters by SPA1 and MYC2 by using stable transgenic lines. Our studies suggest that SPA1 negatively regulates the expression of CAB1 native promoter. MYC2 negatively regulates the activity of Z- and/or G-box containing synthetic as well as native promoters irrespective of light quality. Moreover, MYC2 negatively regulates the expression of Z/G-NOS101-GUS even in the darkness. Furthermore, analyses of tissue specific expression in adult plants suggest that MYC2 strongly regulates the activity of Z- and G-box containing promoters specifically in leaves and stems. In roots, whereas MYC2 positively regulates the activity of the Z-box containing synthetic promoter, it does not seem to control the activity of the G-box containing promoters. Taken together, these results provide insights into SPA1- and MYC2-mediated transcriptional regulation of the Z- and G-box containing promoters in light signaling pathways.