Publications of NIPGR Scientists

Permanent URI for this communityhttps://ndkr-library.nipgr.ac.in/handle/123456789/1

Browse

Now showing 1 - 3 of 3

Arabidopsis CAM7 and HY5 physically interact and directly bind to the HY5 promoter to regulate its expression and thereby promote photomorphogenesis
(American Society of Plant Biologists, 2014) Abbas, Nazia; Maurya, Jay P.; Senapati, Dhirodatta; Gangappa, Sreeramaiah N.; Chattopadhyay, Sudip
Arabidopsis thaliana CALMODULIN7 (CAM7), a unique member of the calmodulin gene family, plays a crucial role as a transcriptional regulator in seedling development. The elongated HYPOCOTYL5 (HY5) bZIP protein, an integrator of multiple signaling pathways, also plays an important role in photomorphogenic growth and light-regulated gene expression. CAM7 acts synergistically with HY5 to promote photomorphogenesis at various wavelengths of light. Although the genetic relationships between CAM7 and HY5 in light-mediated seedling development have been demonstrated, the molecular connectivity between CAM7 and HY5 is unknown. Furthermore, whereas HY5-mediated gene regulation has been fairly well investigated, the transcriptional regulation of HY5 is largely unknown. Here, we report that HY5 expression is regulated by HY5 and CAM7 at various wavelengths of light and also at various stages of development. In vitro and in vivo DNA-protein interaction studies suggest that HY5 and CAM7 bind to closely located T/G- and E-box cis-acting elements present in the HY5 promoter, respectively. Furthermore, CAM7 and HY5 physically interact and regulate the expression of HY5 in a concerted manner. Taken together, these results demonstrate that CAM7 and HY5 directly interact with the HY5 promoter to mediate the transcriptional activity of HY5 during Arabidopsis seedling development.
CAM7 and HY5 genetically interact to regulate root growth and abscisic acid responses
(Taylor & Francis Group, 2014) Abbas, Nazia; Chattopadhyay, Sudip
CAM7, a member of CaM family in Arabidopsis, acts as a transcriptional regulator and enhances photomorphogenic growth and light regulated gene expression under various light conditions. HY5, a bZIP transcription factor, promotes photomorphogenesis at multiple wavelengths of light including far red, red, and blue light. Very recently, it has been shown that CAM7 and HY5 directly interact with the HY5 promoter to regulate the transcriptional activity of HY5 during Arabidopsis seedling development. In this study, we have investigated the root phenotype of cam7 hy5 double mutants and shown that CAM7 and HY5 genetically interact to control the root growth. We have further shown an interdependent function of HY5 and CAM7 in abscisic acid (ABA) responsiveness.
Molecular interactions of GBF1 with HY5 and HYH during light-mediated seedling development in Arabidopsis thaliana
(American Society for Biochemistry and Molecular Biology, 2012) Singh, Aparna; Ram, Hathi; Abbas, Nazia; Chattopadhyay, Sudip
Arabidopsis bZIP transcription factor, GBF1, acts as a differential regulator of cryptochrome-mediated blue light signaling. Whereas the bZIP proteins, HY5 (elongated hypocotyl 5) and HYH (HY5 homologue), are degraded by COP1-mediated proteasomal pathways, GBF1 is degraded by a proteasomal pathway independent of COP1. In this study, we have investigated the functional interrelations of GBF1 with HY5 and HYH in Arabidopsis seedling development. The genetic studies using double and triple mutants reveal that GBF1 largely acts antagonistically with HY5 and HYH in Arabidopsis seedling development. Further, GBF1 and HY5 play more important roles than HYH in blue light-mediated photomorphogenic growth. This study reveals that GBF1 is able to form a G-box-binding heterodimer with HY5 but not with HYH. The in vitro and in vivo studies demonstrate that GBF1 co-localizes with HY5 or HYH in the nucleus and physically interacts with both of the proteins. The protein-protein interaction studies further reveal that the bZIP domain of GBF1 is essential and sufficient for the interaction with HY5 or HYH. Taken together, these data demonstrate the functional interrelations of GBF1 with HY5 and HYH in Arabidopsis seedling development.