Department of Biotechnology and Biophysics, Biocenter, Julius Maximilian University of Würzburg, D-97074 Würzburg, Germany.
Department of Genetics, Faculty of Biology, University of Seville, E-41012 Seville, Spain.
Int J Mol Sci. 2018 Jan 11;19(1):215. doi: 10.3390/ijms19010215.
Fungi possess diverse photosensory proteins that allow them to perceive different light wavelengths and to adapt to changing light conditions in their environment. The biological and physiological roles of the green light-sensing rhodopsins in fungi are not yet resolved. The rice plant pathogen exhibits two different rhodopsins, CarO and OpsA. CarO was previously characterized as a light-driven proton pump. We further analyzed the pumping behavior of CarO by patch-clamp experiments. Our data show that CarO pumping activity is strongly augmented in the presence of the plant hormone indole-3-acetic acid and in sodium acetate, in a dose-dependent manner under slightly acidic conditions. By contrast, under these and other tested conditions, the rhodopsin (NR)-like rhodopsin OpsA did not exhibit any pump activity. Basic local alignment search tool (BLAST) searches in the genomes of ascomycetes revealed the occurrence of rhodopsin-encoding genes mainly in phyto-associated or phytopathogenic fungi, suggesting a possible correlation of the presence of rhodopsins with fungal ecology. In accordance, rice plants infected with a CarO-deficient strain showed more severe bakanae symptoms than the reference strain, indicating a potential role of the CarO rhodopsin in the regulation of plant infection by this fungus.
真菌拥有多样的光感蛋白，使它们能够感知不同的光波，并适应环境中不断变化的光照条件。真菌中绿光感光视紫红质的生物学和生理学作用尚不清楚。水稻病原菌 表现出两种不同的视紫红质，CarO 和 OpsA。CarO 先前被表征为光驱动质子泵。我们通过膜片钳实验进一步分析了 CarO 的泵送行为。我们的数据表明，在植物激素吲哚-3-乙酸和乙酸钠的存在下，CarO 的泵送活性在略微酸性条件下呈剂量依赖性显著增强。相比之下，在这些和其他测试条件下，类似于 NR 的视紫红质 OpsA 没有表现出任何泵活性。在子囊菌的基因组中进行的基本局部比对搜索工具 (BLAST) 搜索揭示了视紫红质编码基因主要存在于与植物相关或植物病原真菌中，这表明视紫红质的存在可能与真菌的生态相关。与此一致，感染了 CarO 缺陷 菌株的水稻植物比参考菌株表现出更严重的恶苗病症状，表明 CarO 视紫红质在该真菌对植物感染的调控中可能发挥作用。
