Institute of Plant Biochemistry, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University, D�sseldorf, Germany.
Department of Plant Biology, Ecology & Evolution, Oklahoma State University, Stillwater, OK, USA.
Plant Cell Physiol. 2019 Mar 1;60(3):702-712. doi: 10.1093/pcp/pcy240.
Galdieria sulphuraria is a unicellular red alga that lives in hot, acidic, toxic metal-rich, volcanic environments, where few other organisms survive. Its genome harbors up to 5% of genes that were most likely acquired through horizontal gene transfer. These genes probably contributed to G.sulphuraria's adaptation to its extreme habitats, resulting in today's polyextremophilic traits. Here, we applied RNA-sequencing to obtain insights into the acclimation of a thermophilic organism towards temperatures below its growth optimum and to study how horizontally acquired genes contribute to cold acclimation. A decrease in growth temperature from 42�C/46�C to 28�C resulted in an upregulation of ribosome biosynthesis, while excreted proteins, probably components of the cell wall, were downregulated. Photosynthesis was suppressed at cold temperatures, and transcript abundances indicated that C-metabolism switched from gluconeogenesis to glycogen degradation. Folate cycle and S-adenosylmethionine cycle (one-carbon metabolism) were transcriptionally upregulated, probably to drive the biosynthesis of betaine. All these cold-induced changes in gene expression were reversible upon return to optimal growth temperature. Numerous genes acquired by horizontal gene transfer displayed temperature-dependent expression changes, indicating that these genes contributed to adaptive evolution in G.sulphuraria.
硫氧还蛋白在细胞中发挥着多种功能，包括调节氧化还原状态、参与蛋白质折叠和代谢途径等。
硫氧还蛋白是一种小分子蛋白质，由 103 个氨基酸残基组成。它含有一个保守的 Cys-Gly-Pro-Cys 结构域，该结构域在氧化还原反应中发挥着重要作用。硫氧还蛋白通过二硫键的形成和还原来调节细胞内的氧化还原状态，从而影响细胞的生长、分化和凋亡等过程。
此外，硫氧还蛋白还可以与其他蛋白质相互作用，形成蛋白质复合物，从而调节这些蛋白质的功能。例如，硫氧还蛋白与转录因子相互作用，可以调节基因的表达；与蛋白酶相互作用，可以调节蛋白质的降解。
总之，硫氧还蛋白是一种重要的细胞内调节蛋白，通过调节氧化还原状态和与其他蛋白质的相互作用，参与多种细胞生理过程的调控。
