Department of Ecology, Evolution and Natural Resources and Institute of Marine and Coastal Science, Rutgers University, New Brunswick, New Jersey 08901, USA.
Nat Commun. 2013;4:1941. doi: 10.1038/ncomms2931.
The limited knowledge we have about red algal genomes comes from the highly specialized extremophiles, Cyanidiophyceae. Here, we describe the first genome sequence from a mesophilic, unicellular red alga, Porphyridium purpureum. The 8,355 predicted genes in P. purpureum, hundreds of which are likely to be implicated in a history of horizontal gene transfer, reside in a genome of 19.7 Mbp with 235 spliceosomal introns. Analysis of light-harvesting complex proteins reveals a nuclear-encoded phycobiliprotein in the alga. We uncover a complex set of carbohydrate-active enzymes, identify the genes required for the methylerythritol phosphate pathway of isoprenoid biosynthesis, and find evidence of sexual reproduction. Analysis of the compact, function-rich genome of P. purpureum suggests that ancestral lineages of red algae acted as mediators of horizontal gene transfer between prokaryotes and photosynthetic eukaryotes, thereby significantly enriching genomes across the tree of photosynthetic life.
我们对红藻基因组的了解有限，这些知识主要来自高度特化的嗜极生物——蓝藻门。在这里，我们描述了第一个来自中嗜热、单细胞红藻——紫球藻的基因组序列。在紫球藻的 8355 个预测基因中，其中数百个可能与水平基因转移的历史有关，这些基因位于一个 19.7 Mbp 的基因组中，其中有 235 个剪接体内含子。对光捕获复合物蛋白的分析揭示了藻类中一种核编码的藻胆蛋白。我们发现了一组复杂的糖活性酶，鉴定了异戊烯基生物合成的甲基赤藓醇磷酸途径所需的基因，并找到了有性繁殖的证据。对紫球藻紧凑、功能丰富的基因组进行分析表明，红藻的祖先谱系在原核生物和光合真核生物之间充当了水平基因转移的中介，从而显著丰富了光合生命之树中所有生物的基因组。
