Institutional Publications
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Item A mitogen-activated protein kinase cascade module, MKK3-MPK6 and MYC2, is involved in blue light-mediated seedling development in Arabidopsis(American Society of Plant Biologists, 2014) Sethi, Vishmita; Raghuram, Badmi; Sinha, Alok Krishna; Chattopadhyay, SudipMitogen-activated protein kinase (MAPK) pathways are involved in several signal transduction processes in eukaryotes. Light signal transduction pathways have been extensively studied in plants; however, the connection between MAPK and light signaling pathways is currently unknown. Here, we show that MKK3-MPK6 is activated by blue light in a MYC2-dependent manner. MPK6 physically interacts with and phosphorylates a basic helix-loop-helix transcription factor, MYC2, and is phosphorylated by a MAPK kinase, MKK3. Furthermore, MYC2 binds to the MPK6 promoter and regulates its expression in a feedback regulatory mechanism in blue light signaling. We present mutational and physiological studies that illustrate the function of the MKK3-MPK6-MYC2 module in Arabidopsis thaliana seedling development and provide a revised mechanistic view of photomorphogenesis.Item 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, SudipAlthough 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.Item MYC2 differentially regulates GATA-box conaining promoters during seedling development in Arabidopsis(Landes Bioscience, 2013) Gangappa, Sreeramaiah N.; Chattopadhyay, SudipMY C2 is an important transcription factor, which modulates transcription by directly binding to Z-, G- and E-box elements present in the promoters of light and different stress responsive genes. Very recently, we have shown that MY C2 plays a role in the regulation of Z- and/or G-box containing promoters during both seedling and adult plant growth. Although, MY C2 does not bind to the GATA box light responsive element (LRE ) in vitro as shown in DNA binding assays, its involvement in the regulation of GATA -box containing promoter in planta, if any, is not known. Here, we report that the promoter activity of GATA-NOS101 in atmyc2 mutant was found to be similar to wild-type in BL and dark grown seedlings, whereas it was found to be lower compared with wild-type as revealed from GUS staining results. Further, we will discuss the consequences of MY C2 regulating GATA -box containing promoter in combination with G-box containing promoters.Item Functional interconnections of HY1 with MYC2 and HY5 in Arabidopsis seedling development(BMC, 2012) Prasad, Babu Rajendra V; Kumar, Selva V; Nandi, Ashis; Chattopadhyay, SudipArabidopsis seedling development is controlled by many regulatory genes involved in multiple signaling pathways. The functional relationships of these genes working in multiple signaling cascades have started to be unraveled. Arabidopsis HY1/HO1 is a rate-limiting enzyme involved in biosynthesis of phytochrome chromophore. HY5 (a bZIP protein) promotes photomorphogenesis, however ZBF1/MYC2 (a bHLH protein) works as a negative regulator of photomorphogenic growth and light regulated gene expression. Further, MYC2 and HY1 have been shown to play important roles in jasmonic acid (JA) signaling pathways. Here, we show the genetic interactions of HY1 with two key transcription factor genes of light signaling, HY5 and MYC2, in Arabidopsis seedling development. Our studies reveal that although HY1 acts in an additive manner with HY5, it is epistatic to MYC2 in light-mediated seedling growth and gene expression. This study further demonstrates that HY1 additively or synergistically functions with HY5, however it works upstream to MYC2 in JA signaling pathways. Taken together, this study demonstrates the functional interrelations of HY1, MYC2 and HY5 in light and JA signaling pathways.Item Functional interconnection of MYC2 and SPA1 in the photomorphogenic seedling development of Arabidopsis(American Society of Plant Biologists, 2010) Gangappa, Sreeramaiah N.; Prasad, V. Babu Rajendra; Chattopadhyay, SudipMYC2 is a basic helix-loop-helix transcription factor that cross talks with light, abscisic acid (ABA), and jasmonic acid (JA) signaling pathways. Here, we have shown that Arabidopsis (Arabidopsis thaliana) MYC2 directly binds to the G-box present in the SUPPRESSOR OF PHYTOCHROME A1 (SPA1) promoter and that it controls the expression of SPA1 in a COP1-dependent manner. Analyses of atmyc2 spa1 double mutants suggest that whereas MYC2 and SPA1 act redundantly to suppress photomorphogenic growth in the dark, they function synergistically for the suppression of photomorphogenic growth in the light. Our studies have also revealed that MYC2-mediated ABA and JA responses are further modulated by SPA1. Taken together, this study demonstrates the molecular and physiological interrelations of MYC2 and SPA1 in light, ABA, and JA signaling pathways.Item MYC2, a bHLH transcription factor, modulates the adult phenotype of SPA1(Landes Bioscience, 2010) Gangappa, Sreeramaiah N.; Chattopadhyay, SudipMYC2 and SPA1 are two key regulatory proteins that negatively regulate light-controlled Arabidopsis seedling development. We have recently demonstrated the genetic and molecular relationships of MYC2 and SPA1 in light and JA (jasmonic acid) signaling pathways. Here, we have further shown the genetic interactions between these two proteins in flowering time and lateral root development.