Ciniglia Claudia, Pollio Antonino, Pozzuoli Elio, Licata Marzia, Nappi Nunzia, Davis Seth J, Iovinella Manuela
Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania "L. Vanvitelli", Via Vivaldi 43, 81100 Caserta, Italy.
Department of Biology, University of Naples Federico II, Via Cinthia, 80126 Napoli, Italy.
Plants (Basel). 2025 Jul 3;14(13):2043. doi: 10.3390/plants14132043.
Membrane transporters are vital for solute movement and localisation across cellular compartments, particularly in extremophilic organisms such as Galdieriales. These red algae thrive in geothermal and metal-rich environments, where adaptive transporter systems contribute to their metabolic flexibility. While inventories of transporter genes in the species have previously been compiled, their phylogenetic origins remain incompletely resolved. Here, we conduct a comparative phylogenetic analysis of three transporter families-Major Facilitator Superfamily (MFS). Amino acid-Polyamine-Organocation () and the natural resistance-associated macrophage protein (Nramp)-selected from overexpressed transcripts in strain SAG 107.79. Using sequences from six Galdieriales species and orthologs from diverse taxa, we reconstructed maximum likelihood trees to assess conservation and potential horizontal gene transfer (HGT). The MFS subfamilies revealed contrasting patterns: sugar porters (SPs) exhibited polyphyly and fungal affinity, suggesting multiple HGT events, while phosphate:H symporters (s) formed a coherent monophyletic group. sequences were exclusive in and extremophilic prokaryotes, indicating a likely prokaryotic origin. In contrast, Nramp transporters were broadly conserved across eukaryotes and prokaryotes, showing no signs of recent HGT. Together, these findings highlight the mosaic evolutionary history of membrane transporters in Galdieriales, shaped by a combination of vertical inheritance and taxon-specific gene acquisition events, and provide new insight into the genomic strategies underpinning environmental resilience in red algae.
膜转运蛋白对于溶质跨细胞区室的移动和定位至关重要，尤其是在诸如加尔迪藻目这样的嗜极生物中。这些红藻在地热和富含金属的环境中茁壮成长，适应性转运系统有助于它们的代谢灵活性。虽然此前已经编制了该物种转运蛋白基因的清单，但其系统发育起源仍未完全解析。在此，我们对三个转运蛋白家族——主要易化子超家族（MFS）、氨基酸-多胺-有机阳离子（APC）和天然抗性相关巨噬细胞蛋白（Nramp）——进行了比较系统发育分析，这些家族是从菌株SAG 107.79中过表达的转录本中挑选出来的。利用来自六个加尔迪藻目物种的序列以及来自不同分类群的直系同源物，我们构建了最大似然树，以评估保守性和潜在的水平基因转移（HGT）。MFS亚家族呈现出截然不同的模式：糖转运蛋白（SPs）表现出多系性和真菌亲和力，表明发生了多次HGT事件，而磷酸氢同向转运蛋白（PHTs）形成了一个连贯的单系群。APC序列在加尔迪藻目和嗜极原核生物中是独有的，表明其可能起源于原核生物。相比之下，Nramp转运蛋白在真核生物和原核生物中广泛保守，没有近期HGT的迹象。总之，这些发现突出了加尔迪藻目膜转运蛋白的镶嵌进化历史，其由垂直遗传和特定分类群基因获得事件共同塑造，并为红藻环境适应能力的基因组策略提供了新的见解。
