Abstract：
Proteorhodopsins have been suggested as an important strategy among phototrophs to capture solar energy in marine environments. The goals of this study was to investigate the diversity of proteorhodopsin genes and to explore their abundance, distribution, and expression in the coastal surface waters of the northern South China Sea, one of the largest marginal seas of the western North Pacific Ocean. Using 21 metagenomes, we recovered proteorhodopsin genes from a wide range of prokaryotic taxa, and chlorophyll a contributed significantly to the community composition of proteorhodopsin-containing microbes. Most proteorhodopsin sequences were predicted to encode green light-absorbing proton pumps and green light-absorbing proteorhodopsin genes were more abundant than blue-absorbing ones. The variations in the conserved residues involved in ion pumping and several uncharacterized proteorhodopsins were observed. The gene abundance pattern of proteorhodopsin types were significantly influenced by the levels of total organic carbon and soluble reactive phosphorus. Gene expression analysis confirmed the importance of proteorhodopsin-based phototrophy and revealed different expressional patterns among major phyla. In tandem, we screened 2295 metagenome-assembled genomes to describe the taxonomic distribution of proteorhodopsins. Bacteroidota are the key lineages encoding proteorhodopsins, but proteorhodopsins were predicated from members of Proteobacteria, Marinisomatota, Myxococcota, Verrucomicrobiota and Thermoplasmatota. Our study expanded the diversity of proteorhodopsins and improve our understanding on the significance of proteorhodopsin-mediated phototrophy in the marine ecosystem.
摘要：
已建议将变形蛋白作为光养生物在海洋环境中捕获太阳能的重要策略。本研究的目的是调查蛋白视紫红质基因的多样性，并探索其丰度，分布，在南海北部沿海地表水中表达，北太平洋西部最大的边缘海之一。使用21个宏基因组，我们从广泛的原核生物分类单元中回收了蛋白视紫红质基因，叶绿素a对含蛋白视紫红质微生物的群落组成有重要贡献。预测大多数蛋白视紫质序列编码绿色光吸收质子泵，并且绿色光吸收蛋白视紫质基因比蓝色吸收基因更丰富。观察到涉及离子泵送的保守残基和一些未表征的蛋白视紫红质的变化。蛋白视紫红质类型的基因丰度模式受总有机碳和可溶性活性磷水平的显著影响。基因表达分析证实了基于蛋白视紫红质的光营养的重要性，并揭示了主要门之间的不同表达模式。串联，我们筛选了2,295个宏基因组组装的基因组来描述蛋白视紫红质的分类学分布。拟杆菌是编码蛋白视紫红质的关键谱系，但是蛋白视紫红质是从变形杆菌的成员预测的，Marinisomatota,粘球菌,野生微生物和热质。我们的研究扩大了蛋白视紫红质的多样性，并增进了我们对蛋白视紫红质介导的光萎缩在海洋生态系统中的重要性的理解。
