Department of Ecology, Evolution and Natural Resources, and Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey 08901, USA.
Plant Physiol. 2012 Apr;158(4):2001-12. doi: 10.1104/pp.112.193896. Epub 2012 Feb 14.
Membrane transporters play a central role in many cellular processes that rely on the movement of ions and organic molecules between the environment and the cell, and between cellular compartments. Transporters have been well characterized in plants and green algae, but little is known about transporters or their evolutionary histories in the red algae. Here we examined 482 expressed sequence tag contigs that encode putative membrane transporters in the economically important red seaweed Porphyra (Bangiophyceae, Rhodophyta). These contigs are part of a comprehensive transcriptome dataset from Porphyra umbilicalis and Porphyra purpurea. Using phylogenomics, we identified 30 trees that support the expected monophyly of red and green algae/plants (i.e. the Plantae hypothesis) and 19 expressed sequence tag contigs that show evidence of endosymbiotic/horizontal gene transfer involving stramenopiles. The majority (77%) of analyzed contigs encode transporters with unresolved phylogenies, demonstrating the difficulty in resolving the evolutionary history of genes. We observed molecular features of many sodium-coupled transport systems in marine algae, and the potential for coregulation of Porphyra transporter genes that are associated with fatty acid biosynthesis and intracellular lipid trafficking. Although both the tissue-specific and subcellular locations of the encoded proteins require further investigation, our study provides red algal gene candidates associated with transport functions and novel insights into the biology and evolution of these transporters.
膜转运蛋白在许多依赖于离子和有机分子在环境和细胞之间以及细胞区室之间移动的细胞过程中发挥核心作用。转运蛋白在植物和绿藻中得到了很好的描述，但对红藻中的转运蛋白或其进化历史知之甚少。在这里，我们研究了 482 个编码经济上重要的红藻紫菜（Bangiophyceae，Rhodophyta）中假定的膜转运蛋白的表达序列标签基因簇。这些基因簇是紫菜和紫菜转录组数据集的一部分。使用系统发生基因组学，我们确定了 30 棵树，这些树支持红藻和绿藻/植物的预期单系性（即植物假说），并且有 19 个表达序列标签基因簇显示出涉及有孔虫的内共生/水平基因转移的证据。分析的大多数（77%）基因簇编码具有未解决的系统发育关系的转运蛋白，这表明很难确定基因的进化历史。我们观察到了海洋藻类中许多钠偶联转运系统的分子特征，以及与脂肪酸生物合成和细胞内脂质运输相关的紫菜转运基因的核心调控的潜力。尽管编码蛋白的组织特异性和亚细胞位置需要进一步研究，但我们的研究为与转运功能相关的红藻基因候选物提供了新的见解，并深入了解了这些转运蛋白的生物学和进化。
