Institutional Publications

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Author: search.filters.author.Mallappa, Chandrashekara

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    GBF 1, a transcription factor of blue light signaling in Arabidopsis, is degraded in the dark by a proteasome-mediated pathway independent of COP 1 and SPA 1
    (The American Society for Biochemistry and Molecular Biology, Inc., 2008) Mallappa, Chandrashekara; Singh, Aparna; Ram, Hathi; Chattopadhyay, Sudip
    Arabidopsis GBF1/ZBF2 is a bZIP transcription factor that plays dual but opposite regulatory roles in cryptochrome-mediated blue light signaling. Here, we show the genetic and molecular interrelation of GBF1 with two well characterized negative regulators of light signaling, COP1 and SPA1, in photomorphogenic growth and light-regulated gene expression. Our results further reveal that GBF1 protein is less abundant in the dark- grown seedlings and is degraded by a proteasome-mediated pathway independent of COP1 and SPA1. Furthermore, COP1 physically interacts with GBF1 and is required for the optimum accumulation of GBF1 protein in light-grown seedlings. Taken together, this study provides a mechanistic view of concerted function of three important regulators in Arabidopsis seedling development.
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    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.
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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.