ABSTRACT
In vitro assays using recombinant enzymes enabled three cDNAs encoding ent-copalyl diphosphate synthases to be identified in wheat (Triticum aestivum): TaCPS1, TaCPS2, and TaCPS3. The phylogenetic tree and expression analyses suggest that TaCPS3 is responsible for gibberellin biosynthesis, while TaCPS1 and TaCPS2 are possible functional homologs of diterpene cyclase genes OsCPS2 and OsCPS4 involved in phytoalexin biosynthesis in rice.
Subject(s)
Alkyl and Aryl Transferases/genetics , DNA, Complementary/genetics , Evolution, Molecular , Oryza/genetics , Oryza/metabolism , Plant Proteins/genetics , Terpenes/metabolism , Triticum/enzymology , Cloning, Molecular , Genes, Plant/genetics , Phylogeny , Sesquiterpenes , Triticum/genetics , PhytoalexinsABSTRACT
Catalytic RNAs with peroxidase activity were obtained by the in vitro selection of RNA aptamer-binding hemin. One of the RNA aptamers selected showed binding affinity to hemin with a dissociation constant of 0.8muM and exhibited high peroxidase activity by forming a complex with hemin. The catalytic efficiency of the RNA-hemin complex was 10-fold higher than that of hemin alone.
Subject(s)
Hemin/genetics , Hemin/metabolism , RNA, Catalytic/chemistry , RNA, Catalytic/metabolism , Base Sequence , Binding Sites/genetics , Hemin/chemistry , Kinetics , Molecular Sequence Data , Nucleic Acid Conformation , Peroxidase/chemistry , Peroxidase/genetics , Peroxidase/metabolismABSTRACT
A new RNA aptamer-binding hemin was synthesized by the in vitro selection (SELEX) method. A pool of 103 bases single strand DNAs containing a randomized sequence of 59 bases was synthesized. The pool was incubated with hemin on hemin-immobilized affinity column. Bound RNAs were eluted off with hemin solution and amplified by PCR. After 3 rounds of selection process, the selected RNAs were cloned and sequenced. Some RNA aptamers, which have affinity to hemin, was selected.
Subject(s)
Aptamers, Nucleotide/metabolism , Hemin/metabolism , Hemin/chemistry , SELEX Aptamer TechniqueABSTRACT
Rice (Oryza sativa L.) produces a variety of diterpene phytoalexins, such as momilactones, phytocassanes, and oryzalexins. Momilactone B was previously identified as an allelopathic substance exuded from the roots of rice. We identified in this present study momilactone A and phytocassanes A-E in extracts of, and exudates from, the roots of rice seedlings. The concentration of each compound was of the same order of magnitude as that of momilactone B. Expression analyses of the diterpene cyclase genes responsible for the biosynthesis of momilactones and phytocassanes suggest that these phytoalexins found in roots are primarily biosynthesized in those roots. None of phytocassanes B-E exhibited allelopathic activity against dicot seedling growth, whereas momilactone A showed much weaker allelopathic activity than momilactone B. The exudation of diterpene phytoalexins from the roots might be part of a system for defense against root-infecting pathogens.
