Key Laboratory of Marine Genetics and Breeding (Ocean University of China) Ministry of Education, Qingdao 266003, China.
Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China.
Mar Drugs. 2019 Jan 21;17(1):70. doi: 10.3390/md17010070.
The red seaweed is an ideal research model for dissecting the molecular mechanisms underlying its robust acclimation to abiotic stresses in intertidal zones. Glycine betaine (GB) was an important osmolyte in maintaining osmotic balance and stabilizing the quaternary structure of complex proteins under abiotic stresses (drought, salinity, etc.) in plants, animals, and bacteria. However, the existence and possible functions of GB in remain elusive. In this study, we observed the rapid accumulation of GB in desiccated blades, identifying its essential roles in protecting cells against severe osmotic stress. Based on the available genomic and transcriptomic information of , we computationally identified genes encoding the three key enzymes in the GB biosynthesis pathway: phosphoethanolamine -methyltransferase (PEAMT), choline dehydrogenase (CDH), and betaine aldehyde dehydrogenase (BADH). had an extraordinarily expanded gene copy number of CDH (up to seven) compared to other red algae. Phylogeny analysis revealed that in addition to the one conservative CDH in red algae, the other six might have originated from early gene duplication events. In dehydration stress, multiple CDH paralogs and PEAMT genes were coordinating up-regulated and shunted metabolic flux into GB biosynthesis. An elaborate molecular mechanism might be involved in the transcriptional regulation of these genes.
红海茸是一种理想的研究模式，可用于剖析其在潮间带适应非生物胁迫的分子机制。甘氨酸甜菜碱（GB）是植物、动物和细菌中维持渗透平衡和稳定复杂蛋白质四级结构的重要渗透物，可应对非生物胁迫（干旱、盐度等）。然而，在 中 GB 的存在和可能的功能仍然难以捉摸。在这项研究中，我们观察到干燥的 叶片中 GB 的快速积累，确定了其在保护细胞免受严重渗透胁迫方面的重要作用。基于 的可用基因组和转录组信息，我们通过计算鉴定了编码 GB 生物合成途径中三个关键酶的基因：磷酸乙醇胺 -甲基转移酶（PEAMT）、胆碱脱氢酶（CDH）和甜菜碱醛脱氢酶（BADH）。与其他红藻相比， 的 CDH 基因拷贝数异常扩增（多达七个）。系统发育分析表明，除了红藻中保守的一个 CDH 外，其他六个可能起源于早期基因复制事件。在脱水胁迫下，多个 CDH 同源基因和 PEAMT 基因协调上调，并将代谢通量分流到 GB 生物合成中。可能涉及这些基因的转录调控的精巧分子机制。
