Browsing by Author "Kundu, Snehangshu"

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    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.
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    SHORT HYPOCOTYL IN WHITE LIGHT1, a serine-arginine-aspartate rich protein in Arabidopsis, acts as a negative regulator of photomorphogenic growth
    (American Society of Plant Biologists, 2008) Bhatia, Shikha; Gangappa, Sreeramaiah N.; Kuswaha, Ritu; Kundu, Snehangshu; Chattopadhyay, Sudip
    Light is an important factor for plant growth and development. We have identified and functionally characterized a regulatory gene SHORT HYPOCOTYL IN WHITE LIGHT1 (SHW1) involved in Arabidopsis (Arabidopsis thaliana) seedling development. SHW1 encodes a unique serine-arginine-aspartate-rich protein, which is constitutively localized in the nucleus of hypocotyl cells. Transgenic analyses have revealed that the expression of SHW1 is developmentally regulated and is closely associated with the photosynthetically active tissues. Genetic and molecular analyses suggest that SHW1 acts as a negative regulator of light-mediated inhibition of hypocotyl elongation, however, plays a positive regulatory role in light-regulated gene expression. The shw1 mutants also display shorter hypocotyl in dark, and analyses of shw1 cop1 double mutants reveal that SHW1 acts nonredundantly with COP1 to control hypocotyl elongation in the darkness. Taken together, this study provides evidences that SHW1 is a regulatory protein that is functionally interrelated to COP1 and plays dual but opposite regulatory roles in photomorphogenesis.