Synthesis, Regulation and Degradation of Carotenoids Under Low Level UV-B Radiation in the Filamentous Cyanobacterium Chlorogloeopsis fritschii PCC 6912
Synthesis, Regulation and Degradation of Carotenoids Under Low Level UV-B Radiation in the Filamentous Cyanobacterium Chlorogloeopsis fritschii PCC 6912
复制标题
DOI：
10.3389/fmicb.2020.00163
复制
发表时间：
2020-02-12
影响因子：
5.2
通讯作者：
Greig, Carolyn
中科院分区：
文献类型：
--
作者：
Llewellyn, Carole A.;Airs, Ruth L.;Greig, Carolyn
蓝藻中的类胡萝卜素在低水平UV-B辐射损伤的防护和修复中起着重要作用。在这里，我们使用转录组学和代谢组学HPLC色素分析比较类胡萝卜素途径调节丝状蓝藻Chlorogloeopsis fritschii PCC 6912暴露于白色光和白色光补充低水平的UV-B。在UV-B下，类胡萝卜素转录调控的变化与类胡萝卜素的生成（类胡萝卜素的合成），光保护和类胡萝卜素的切割。转录调控反映在相应的色素签名。从香叶基香叶基二磷酸到番茄红素的所有胡萝卜素生成途径基因均上调。与酮化途径相关的基因同源物（crtW，crtR，cruF和cruG）的表达显著增加，从而使海胆酮和黄质浓度显著增加。存在四种β-胡萝卜素酮酶（crtO和crtW）的基因同源物，但只有一种crtW上调。编码用于将γ-胡萝卜素转化为粘液醇2 '-甲基戊糖苷的酶（CruF、CrtR和CruG）的推定基因被上调。玉米黄质和钙黄质羟基化合成虾青素的途径（CrtR和CrtG的基因同源物）没有上调，反映在玉米黄质、钙黄质和虾青素中未改变的相应色素浓度中。与光保护相关的非光化学淬灭相关的橙色-类胡萝卜素-蛋白（OCP）和相关的毒性恢复-蛋白（FRP）的转录物上调，一个类胡萝卜素结合螺旋-类胡萝卜素-蛋白（HCP）基因同源物被下调。鉴定了编码负责类胡萝卜素裂解的推定的脱辅基类胡萝卜素相关类胡萝卜素加氧酶的基因的多个拷贝，包括与视黄醇产生酶同源的上调的脱辅基-β-胡萝卜素醛加氧酶基因。我们的研究提供了全面的了解光调节过程，调节合成，光保护和类胡萝卜素的蓝藻细胞暴露于低水平的UV-B裂解。这对于理解代谢调节如何响应变化的环境以及如何为生物技术目的调节代谢是重要的。
Carotenoids in cyanobacteria play an important role in protecting against and in repairing damage against low level UV-B radiation. Here we use transcriptomics and metabolomic HPLC pigment analysis to compare carotenoid pathway regulation in the filamentous cyanobacterium Chlorogloeopsis fritschii PCC 6912 exposed to white light and to white light supplemented with low level UV-B. Under UV-B changes in carotenoid transcription regulation were found associated with carotenogenesis (carotenoid synthesis), photoprotection and carotenoid cleavage. Transcriptional regulation was reflected in corresponding pigment signatures. All carotenogenesis pathway genes from geranylgeranyl-diphosphate to lycopene were upregulated. There were significant increases in expression of gene homologs (crtW, crtR, cruF, and cruG) associated with routes to ketolation to produce significant increases in echinenone and canthaxanthin concentrations. There were gene homologs for four beta-carotene-ketolases (crtO and crtW) present but only one crtW was upregulated. Putative genes encoding enzymes (CruF, CrtR, and CruG) for the conversion of gamma-carotene to myxol 2 '-methylpentoside were upregulated. The hydroxylation pathway to nostaxanthin via zeaxanthin and caloxanthin (gene homologs for CrtR and CrtG) were not upregulated, reflected in the unchanged corresponding pigment concentrations in zeaxanthin, caloxanthin and nostaxanthin, Transcripts for the non-photochemical quenching related Orange-Carotenoid-Protein (OCP) and associated Fluoresence-Recovery-Protein (FRP) associated with photoprotection were upregulated, and one carotenoid binding Helical-Carotenoid-Protein (HCP) gene homolog was downregulated. Multiple copies of genes encoding putative apocarotenoid related carotenoid oxygenases responsible for carotenoid cleavage were identified, including an upregulated apo-beta-carotenal-oxygenase gene homologous to a retinal producing enzyme. Our study provides holistic insight into the photoregulatory processes that modulate the synthesis, photoprotection and cleavage of carotenoids in cyanobacterial cells exposed to low level UV-B. This is important to understanding how regulation of metabolism responds to a changing environment and how metabolism can be modulated for biotechnological purposes.