A novel mitochondrial DnaJ/Hsp40 family protein BIL2 promotes plant growth and resistance against environmental stress in brassinosteroid signaling

Funding Information: Acknowledgments We thank Dr. Tsuyoshi Nakagawa (Shimane University) for the gift of the gateway vectors, pGWB2, pGWB80, pGWB5, and pGWB3. This work was supported in part by funding from the Program for Promotion of Basic Research Activities for Innovation Bioscience (PROBRAIN) to T.N. and T.A., and CREST, Japan Science and Technology Agency to T.N. and T.A.Plant steroid hormones, brassinosteroids, are essential for growth, development and responses to environmental stresses in plants. Although BR signaling proteins are localized in many organelles, i.e., the plasma membrane, nuclei, endoplasmic reticulum and vacuole, the details regarding the BR signaling pathway from perception at the cellular membrane receptor BRASSINOSTEROID INSENSITIVE 1 (BRI1) to nuclear events include several steps. Brz (Brz220) is a specific inhibitor of BR biosynthesis. In this study, we used Brz-mediated chemical genetics to identify Brz-insensitive-long hypocotyls 2-1D (bil2-1D). The BIL2 gene encodes a mitochondrial-localized DnaJ/Heat shock protein 40 (DnaJ/Hsp40) family, which is involved in protein folding. BIL2-overexpression plants (BIL2-OX) showed cell elongation under Brz treatment, increasing the growth of plant inflorescence and roots, the regulation of BR-responsive gene expression and suppression against the dwarfed BRI1-deficient mutant. BIL2-OX also showed resistance against the mitochondrial ATPase inhibitor oligomycin and higher levels of exogenous ATP compared with wild-type plants. BIL2 participates in resistance against salinity stress and strong light stress. Our results indicate that BIL2 induces cell elongation during BR signaling through the promotion of ATP synthesis in mitochondria.Peer reviewe

Trypanocidal Activity of 2,5-Diphenyloxazoles Isolated from the Roots of <i>Oxytropis lanata</i>

Eleven 2,5-diphenyloxazole derivatives (<b>1</b>–<b>11</b>), together with six known isoflavonoid derivatives, were isolated from the roots of <i>Oxytropis lanata</i>. The 2,5-diphenyloxazole (<b>1</b>) obtained proved to be identical to a standard sample used as a scintillator and liquid laser dye. The other oxazole derivatives isolated were found to have one to four hydroxy and/or <i>O</i>-methyl groups in their phenyl rings. Seven of the oxazole derivatives obtained are new (<b>3</b>–<b>9</b>). The inhibitory activity of the isolated compounds was evaluated against <i>Trypanosoma congolense</i>, the causative agent of African trypanosomosis in animals. Oxazoles with di- and trihydroxy groups showed trypanocidal activity, and 2-(2′,3′-dihydroxyphenyl)-5-(2″-hydroxyphenyl)­oxazole (<b>4</b>) exhibited the most potent inhibitory activity (IC₅₀ 1.0 μM)