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The Arabidopsis Mediator Complex Subunit MED19a is Involved in ABI5-mediated ABA Responses
Xiaohui Li,Rui Yang,Yifu Gong,Haimin Chen 한국식물학회 2018 Journal of Plant Biology Vol.61 No.2
Arabidopsis Mediator complex subunit 19a(MED19a), which mediates interactions between transcriptionalregulators and RNA polymerase II, plays a critical role inplant response to infection by pathogens. However, the rolesof MED19a in other signaling pathways are unknown. Here,we report that MED19a plays an important role in regulationof abscisic acid (ABA)-mediated transcriptional regulation inArabidopsis. Plants deficient in MED19a showed reducedsensitivity to ABA inhibition of seed germination, cotyledongreening, root growth, and stomatal opening. MED19adeficientmutants also had reduced resistance to droughtstress, evidenced by high water-loss rates and low survivalrates. Molecular genetic analysis revealed that MED19amutants had down-regulated ABA-induced genes, includingEm1, Em6, and RD29B, and MED19a could occupy thepromoters of Em1 and Em6 in an ABA-dependent manner. Furthermore, MED19a interacted with the transcription factorABA-insensitive 5 (ABI5) in split-luciferase complementationassays and co-immunoprecipitation assays. An analysis ofdouble mutants (med19a-2 and abi5-7) suggested that theaction of MED19a in ABA signaling was dependent uponABI5. Furthermore, MED19a and ABI5 influenced eachother in recruiting the promoters of the target genes Em1 andEm6, which are involved in embryonic development. Altogether,these results indicate that MED19a acts as a positive regulator inABI5-mediated ABA responses.
Molecular Cloning and Characterization of a Novel Stem-specific Gene from Camptotheca acuminata
Pi, Yan,Liao, Zhihua,Chai, Yourong,Zeng, Hainian,Wang, Peng,Gong, Yifu,Pang, Yongzhen,Sun, Xiaofen,Tang, Kexuan Korean Society for Biochemistry and Molecular Biol 2006 Journal of biochemistry and molecular biology Vol.39 No.1
In higher plants, P450s participate in the biosynthesis of many important secondary metabolites. Here we reported for the first time the isolation of a new cytochrome P450 cDNA that expressed in a stem-specific manner from Camptotheca acuminata (designated as CaSS), a native medicinal plant species in China, using RACE-PCR. The full-length cDNA of CaSS was 1735 bp long containing a 1530 bp open reading frame (ORF) encoding a polypeptide of 509 amino acids. Bioinformatic analysis revealed that CASS contained a heme-binding domain PFGXGRRXCX and showed homology to other plant cytochrome P450 monooxygenases and hydroxylases. Southern blotting analysis revealed that there was only one copy of the CaSS present in the genome of Camptotheca acuminata. Northern blotting analysis revealed that CaSS expressed, in a tissue-specific manner, highly in stem and lowly in root, leaf and flower. Our study suggests that CaSS is likely to be involved in the phenylpropanoid pathway.
Cloning and Functional Analysis of a cDNA Encoding Ginkgo biloba Farnesyl Diphosphate Synthase
Kexuan Tang,Peng Wang,Zhihua Liao,Liang Guo,Wenchao Li,Min Chen,Yan Pi,Yifu Gong,Xiaofen Sun 한국분자세포생물학회 2004 Molecules and cells Vol.18 No.2
Farnesyl diphosphate synthase (FPS; EC2.5.1.1/EC2. 5.1.10) catalyzes the synthesis of farnesyl diphosphate, and provides precursor for biosynthesis of sesquiterpene and isoprenoids containing more than 15 isoprene units in Ginkgo biloba. Here we report the cloning, characterization and functional analysis of a new cDNA encoding FPS from G. biloba. The full-length cDNA (designated GbFPS) had 1731 bp with an open reading frame of 1170 bp encoding a polypeptide of 390 amino acids. The deduced GbFPS was similar to other known FPSs and contained all the conserved regions of trans-prenyl chain-elongating enzymes. Structural modeling showed that GbFPS had the typical structure of FPS, the most prominent feature of which is the arrangement of 13 core helices around a large central cavity. Southern blot analysis revealed a small FPS gene family in G. biloba. Expression analysis indicated that GbFPS expression was high in roots and leaves, and low in stems. Functional complementation of GbFPS in an FPS-deficient strain confirmed that GbFPS mediates farnesyl diphosphate biosynthesis.