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It has been suggested that plant phytochromes are autophosphorylating serine/threonine kinases. However, the biochemical properties and functional roles of putative phytochrome kinase activity in plant light signalling are largely unknown. Here, we describe the biochemical and functional characterization of Avena sativa phytochrome A (AsphyA) as a potential protein kinase. We provide evidence that phytochrome-interacting factors (PIFs) are phosphorylated by phytochromes in vitro. Domain mapping of AsphyA shows that the photosensory core region consisting of PAS-GAF-PHY domains in the N-terminal is required for the observed kinase activity. Moreover, we demonstrate that transgenic plants expressing mutant versions of AsphyA, which display reduced activity in in vitro kinase assays, show hyposensitive responses to far-red light. Further analysis reveals that far-red light-induced phosphorylation and degradation of PIF3 are significantly reduced in these transgenic plants. Collectively, these results suggest a positive relationship between phytochrome kinase activity and photoresponses in plants.

Obg is a ribosome-associated GTPase essential for bacterial viability and is conserved in most organisms, from bacteria to eukaryotes. Obg is also expressed in plants, which predicts an important role for this molecule in plant viability; however, the functions of the plant Obg homologs have not been reported. Here, we first identified Arabidopsis AtObgC as a plant chloroplast-targeting Obg and elucidated its molecular biological and physiological properties. AtObgC encodes a plant-specific Obg GTPase that contains an N-terminal region for chloroplast targeting and has intrinsic GTP hydrolysis activity. A targeting assay using a few AtObgC N-terminal truncation mutants revealed that AtObgC localizes to chloroplasts and its transit peptide consists of more than 50 amino acid residues. Interestingly, GFP-fused full-length AtObgC exhibited a punctate staining pattern in chloroplasts of Arabidopsis protoplasts, which suggests a dimerization or multimerization of AtObgC. Moreover, its Obg fold was indispensable for the generation of the punctate staining pattern, and thus, was supposed to be important for such oligomerization of AtObgC by mediating the protein-protein interaction. In addition, the T-DNA insertion AtObgC null mutant exhibited an embryonic lethal phenotype that disturbed the early stage of embryogenesis. Altogether, our results provide a significant implication that AtObgC as a chloroplast targeting GTPase plays an important role at the early embryogenesis by exerting its function in chloroplast protein synthesis.

Computer-aided design and computer-aided manufacturing (CAD-CAM) technology has revolutionized workflow in dentistry because of its speed, convenience, and accuracy. [1][2][3][4] Accuracy of definitive restoration fabricated in a fully digital workflow is a crucial factor determining clinical success. 5 When the restoration fails to seat properly in the cavity, more time needs to be spent for the necessary adjustments. If the spacer parameters are set at a high value during the CAD procedure to allow ease of seating, large internal and marginal gaps occur between the tooth and restoration. Poor adaptation jeopardizes longevity in indirect restorations, [6][7][8][9][10][11] as large discrepancies may lead to clinical complications such as secondary caries or periodontal inflammation due to plaque accumulation. 12,13 The accuracy of intraoral scanners (IOSs) has been described, according to the definition 5725-1 of the International Organization for Standardization 14 by using the following terms: trueness, referring to the closeness of agreement between the arithmetic mean of a large number of test results and the true or accepted reference value and precision, referringThis study was supported by the Yonsei University College of Dentistry (6-2017-0015).