The Experts below are selected from a list of 48800874 Experts worldwide ranked by ideXlab platform
Magnus Holm - One of the best experts on this subject based on the ideXlab platform.
-
the b box domain protein bbx21 promotes photomorphogenesis
Plant Physiology, 2017Co-Authors: Dongqing Xu, Yan Jiang, Jian Li, Magnus HolmAbstract:B-box-containing (BBX) proteins play critical roles in a variety of cellular and developmental processes in plants. BBX21 (also known as SALT TOLERANCE HOMOLOG2), which contains two B-box domains in tandem at the N terminus, has been previously demonstrated as a key component involved in the COP1-HY5 signaling hub. However, the exact molecular and physiological roles of B-box domains in BBX21 are largely unclear. Here, we found that structurally disruption of the second B-box domain, but not the first one, in BBX21 completely abolishes its biological and physiological activity in conferring hyperphotomorphogenetic phenotype in Arabidopsis (Arabidopsis thaliana). Intact B-box domains in BBX21 are not required for interaction with COP1 and its degradation by COP1 via the 26S proteasome system. However, disruption of the second B-box of BBX21 nearly impairs its ability for binding of T/G-box within the HY5 promoter both in vitro and in vivo, as well as controlling HY5 and HY5-regulated gene expression in Arabidopsis seedlings. Taken together, this study provides a mechanistic framework in which BBX21 directly binds to the T/G-box present in the HY5 promoter possibly through its second B-box domain, which in turn controls HY5 and HY5-regulated gene expression to promote photomorphogenesis.
-
bbx21 an arabidopsis b box protein directly activates hy5 and is targeted by cop1 for 26s proteasome mediated degradation
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Yan Jiang, Fang Lin, Magnus HolmAbstract:BBX21 (also known as SALT TOLERANCE HOMOLOG 2), a B-box (BBX)-containing protein, has been previously identified as a positive regulator of light signaling; however, the precise role of BBX21 in regulating seedling photomorphogenesis remains largely unclear. In this study, we report that CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) interacts with BBX21 in vivo and is able to ubiquitinate BBX21 in vitro. Thus, BBX21 is targeted for 26S proteasome-mediated degradation in dark-grown Arabidopsis seedlings in a COP1-dependent manner. Moreover, we show that BBX21 binds to the T/G-box in the ELONGATED HYPOCOTYL 5 (HY5) promoter and directly activates HY5 expression in the light. Transgenic seedlings overexpressing BBX21 exhibit dramatically shortened hypocotyls in the light, and this phenotype is dependent on a functional HY5. Taken together, our data suggest a molecular base underlying BBX21-mediated seedling photomorphogenesis, indicating that BBX21 is a pivotal component involved in the COP1-HY5 regulatory hub.
Yan Jiang - One of the best experts on this subject based on the ideXlab platform.
-
b box containing proteins bbx30 and bbx31 acting downstream of hy5 negatively regulate photomorphogenesis in arabidopsis
Plant Physiology, 2019Co-Authors: Xing Wang Deng, Dongqing Xu, Yan Jiang, Yueqin Heng, Mingquan Ding, Hua Zhou, Xianhai ZhaoAbstract:Light-mediated seedling development is coordinately controlled by a variety of key regulators. Here, we identified two B-box (BBX)-containing proteins, BBX30 and BBX31, as repressors of photomorphogenesis. ELONGATED HYPOCOTYL5, a central regulator of light signaling, directly binds to the G-box cis-element present in the promoters of BBX30 and BBX31 and negatively controls their transcription levels in the light. Seedlings with mutations in BBX30 or BBX31 are hypersensitive to light, whereas the overexpression of BBX30 or BBX31 leads to hypo-photomorphogenic growth in the light. Furthermore, transgenic and phenotypic analysis revealed that the B-box domain of BBX30 or BBX31 is essential for their respective functioning in the regulation of photomorphogenic development in plants. In conclusion, BBX30 and BBX31 act as key negative regulators of light signaling, and their transcription is repressed by ELONGATED HYPOCOTYL5 through directly associating with their promoters.
-
the b box domain protein bbx21 promotes photomorphogenesis
Plant Physiology, 2017Co-Authors: Dongqing Xu, Yan Jiang, Jian Li, Magnus HolmAbstract:B-box-containing (BBX) proteins play critical roles in a variety of cellular and developmental processes in plants. BBX21 (also known as SALT TOLERANCE HOMOLOG2), which contains two B-box domains in tandem at the N terminus, has been previously demonstrated as a key component involved in the COP1-HY5 signaling hub. However, the exact molecular and physiological roles of B-box domains in BBX21 are largely unclear. Here, we found that structurally disruption of the second B-box domain, but not the first one, in BBX21 completely abolishes its biological and physiological activity in conferring hyperphotomorphogenetic phenotype in Arabidopsis (Arabidopsis thaliana). Intact B-box domains in BBX21 are not required for interaction with COP1 and its degradation by COP1 via the 26S proteasome system. However, disruption of the second B-box of BBX21 nearly impairs its ability for binding of T/G-box within the HY5 promoter both in vitro and in vivo, as well as controlling HY5 and HY5-regulated gene expression in Arabidopsis seedlings. Taken together, this study provides a mechanistic framework in which BBX21 directly binds to the T/G-box present in the HY5 promoter possibly through its second B-box domain, which in turn controls HY5 and HY5-regulated gene expression to promote photomorphogenesis.
-
bbx21 an arabidopsis b box protein directly activates hy5 and is targeted by cop1 for 26s proteasome mediated degradation
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Yan Jiang, Fang Lin, Magnus HolmAbstract:BBX21 (also known as SALT TOLERANCE HOMOLOG 2), a B-box (BBX)-containing protein, has been previously identified as a positive regulator of light signaling; however, the precise role of BBX21 in regulating seedling photomorphogenesis remains largely unclear. In this study, we report that CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) interacts with BBX21 in vivo and is able to ubiquitinate BBX21 in vitro. Thus, BBX21 is targeted for 26S proteasome-mediated degradation in dark-grown Arabidopsis seedlings in a COP1-dependent manner. Moreover, we show that BBX21 binds to the T/G-box in the ELONGATED HYPOCOTYL 5 (HY5) promoter and directly activates HY5 expression in the light. Transgenic seedlings overexpressing BBX21 exhibit dramatically shortened hypocotyls in the light, and this phenotype is dependent on a functional HY5. Taken together, our data suggest a molecular base underlying BBX21-mediated seedling photomorphogenesis, indicating that BBX21 is a pivotal component involved in the COP1-HY5 regulatory hub.
Xiangqi Zhang - One of the best experts on this subject based on the ideXlab platform.
-
Genome-wide analysis of the MADS-Box gene family in Brachypodium distachyon.
PloS one, 2014Co-Authors: Bo Wei, Rongzhi Zhang, Juan-juan Guo, Danmei Liu, Fan Renchun, Long Mao, Xiangqi ZhangAbstract:MADS-Box genes are important transcription factors for plant development, especially floral organogenesis. Brachypodium distachyon is a model for biofuel plants and temperate grasses such as wheat and barley, but a comprehensive analysis of MADS-Box family proteins in Brachypodium is still missing. We report here a genome-wide analysis of the MADS-Box gene family in Brachypodium distachyon. We identified 57 MADS-Box genes and classified them into 32 MIKCc-type, 7 MIKC*-type, 9 Mα, 7 Mβ and 2 Mγ MADS-Box genes according to their phylogenetic relationships to the Arabidopsis and rice MADS-Box genes. Detailed gene structure and motif distribution were then studied. Investigation of their chromosomal localizations revealed that Brachypodium MADS-Box genes distributed evenly across five chromosomes. In addition, five pairs of type II MADS-Box genes were found on synteny blocks derived from whole genome duplication blocks. We then performed a systematic expression analysis of Brachypodium MADS-Box genes in various tissues, particular floral organs. Further detection under salt, drought, and low-temperature conditions showed that some MADS-Box genes may also be involved in abiotic stress responses, including type I genes. Comparative studies of MADS-Box genes among Brachypodium, rice and Arabidopsis showed that Brachypodium had fewer gene duplication events. Taken together, this work provides useful data for further functional studies of MADS-Box genes in Brachypodium distachyon.
Matthieu Rivain - One of the best experts on this subject based on the ideXlab platform.
-
white box security notions for symmetric encryption schemes
Selected Areas in Cryptography, 2013Co-Authors: Cecile Delerablee, Tancrede Lepoint, Pascal Paillier, Matthieu RivainAbstract:White-box cryptography has attracted a growing interest from researchers in the last decade. Several white-box implementations of standard block-ciphers DES, AES have been proposed but they have all been broken. On the other hand, neither evidence of existence nor proofs of impossibility have been provided for this particular setting. This might be in part because it is still quite unclear what white-box cryptography really aims to achieve and which security properties are expected from white-box programs in applications. This paper builds a first step towards a practical answer to this question by translating folklore intuitions behind white-box cryptography into concrete security notions. Specifically, we introduce the notion of white-box compiler that turns a symmetric encryption scheme into randomized white-box programs, and we capture several desired security properties such as one-wayness, incompressibility and traceability for white-box programs. We also give concrete examples of white-box compilers that already achieve some of these notions. Overall, our results open new perspectives on the design of white-box programs that securely implement symmetric encryption.
Changxian Yang - One of the best experts on this subject based on the ideXlab platform.
-
a tomato b box protein slbbx20 modulates carotenoid biosynthesis by directly activating phytoene synthase 1 and is targeted for 26s proteasome mediated degradation
New Phytologist, 2019Co-Authors: Cheng Xiong, Dan Luo, Aihua Lin, Chunli Zhang, Libo Shan, Qiaomei Zhang, Bin Hua, Zilv Yuan, Junhong Zhang, Changxian YangAbstract:Carotenoids play important roles in many biological processes, such as light harvesting, photoprotection and visual attraction in plants. However, the regulation of carotenoid biosynthesis is still not fully understood. Here, we demonstrate that SlBBX20, a B-box (BBX) zinc-finger transcription factor, is a positive regulator of carotenoid accumulation in tomato (Solanum lycopersicum). Overexpression of SlBBX20 leads to dark green fruits and leaves and higher levels of carotenoids relative to the wild-type. Interactions between SlBBX20 and DE-ETIOLATED 1 (SlDET1) lead to the ubiquitination and 26S proteasome-mediated degradation of SlBBX20. Moreover, deficiencies in the components of the CUL4-DDB1-DET1 complex enhanced the stability of the SlBBX20 protein. Thus, we conclude that SlBBX20 is a substrate of the CUL4-DDB1-DET1 E3 ligase. SlBBX20 can activate the expression of PHYTOENE SYNTHASE 1, encoding a key enzyme in carotenoid biosynthesis, by directly binding to a G-box motif in its promoter, which results in the elevated levels of carotenoids in SlBBX20 overexpression lines. We identified a key regulator of carotenoid biosynthesis and demonstrated that the stability of SlBBX20 is regulated by ubiquitination. These findings provide us a new target for the genetic improvement of the nutritional quality of tomato fruit.
