Thiamine metabolism genes in diatoms are not regulated by thiamine despite the presence of predicted riboswitches.
Thiamine metabolism genes in diatoms are not regulated by thiamine despite the presence of predicted riboswitches.
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DOI：
10.1111/nph.18296
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发表时间：
2022-09
期刊：
影响因子：
9.4
通讯作者：
Smith, Alison G.
中科院分区：
文献类型：
--
作者：
Llavero-Pasquina, Marcel;Geisler, Katrin;Holzer, Andre;Mehrshahi, Payam;Mendoza-Ochoa, Gonzalo, I;Newsad, Shelby A.;Davey, Matthew P.;Smith, Alison G.
关键词：
硫胺素焦磷酸（TPP）是所有物种必需的辅助因子，在细菌、真菌、植物和绿藻中通过TPP核开关调节的代谢昂贵途径进行生物合成。硅藻是一种微藻，占全球初级产量的约20%。据预测，它们在一些硫胺素代谢相关基因的3'UTR中含有TPP适体，但对它们的功能和调控知之甚少。我们使用生物信息学、抗代谢物生长测定、RT - qPCR、靶向诱变和报告构建来测试预测的TPP核开关是否对硅藻中硫胺素的补充有反应。利用基因编辑技术研究了三角褐指藻（Phaeodactylum tricornutum）中TPP相关核开关基因的功能。我们发现，含有TPP适体的硫胺素相关基因对补充硫胺素或其前体4 -氨基- 5 -羟甲基- 2 -甲基嘧啶（HMP）没有反应，而编码HMP - P合成酶的thc基因中TPP适体的靶向突变不会解除三角角藻硫胺素的生物合成。通过基因组编辑，我们确定ptthc是硫胺素生物合成所必需的，另一个基因PtSSSP是硫胺素摄取所必需的。我们的研究结果强调了实验测试生物信息学适体预测的重要性，并为塑造具有全球生物地球化学重要性的海洋微生物群落结构的硫胺素代谢提供了新的见解。
Thiamine pyrophosphate (TPP), an essential co‐factor for all species, is biosynthesised through a metabolically expensive pathway regulated by TPP riboswitches in bacteria, fungi, plants and green algae. Diatoms are microalgae responsible for c. 20% of global primary production. They have been predicted to contain TPP aptamers in the 3′UTR of some thiamine metabolism‐related genes, but little information is known about their function and regulation. We used bioinformatics, antimetabolite growth assays, RT‐qPCR, targeted mutagenesis and reporter constructs to test whether the predicted TPP riboswitches respond to thiamine supplementation in diatoms. Gene editing was used to investigate the functions of the genes with associated TPP riboswitches in Phaeodactylum tricornutum. We found that thiamine‐related genes with putative TPP aptamers are not responsive to supplementation with thiamine or its precursor 4‐amino‐5‐hydroxymethyl‐2‐methylpyrimidine (HMP), and targeted mutation of the TPP aptamer in the THIC gene encoding HMP‐P synthase does not deregulate thiamine biosynthesis in P. tricornutum. Through genome editing we established that PtTHIC is essential for thiamine biosynthesis and another gene, PtSSSP, is necessary for thiamine uptake. Our results highlight the importance of experimentally testing bioinformatic aptamer predictions and provide new insights into the thiamine metabolism shaping the structure of marine microbial communities with global biogeochemical importance.
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