三角褐指藻pds基因生物信息学与诱导表达分析

Induced Expression and Bioinformatic Analysis About Phytoene Desaturase Gene(pds) From Phaeodactylum tricornutum

岩藻黄素是一类具有重要药用价值和开发价值的新型海洋药物,八氢番茄红素脱氢酶(PDS)是三角褐指藻类岩藻黄素生物合成途径中的一个重要的限速酶。为了更好地开发和利用岩藻黄素,通过RT-PCR克隆了三角褐指藻pds基因(Ptpds,Gen Bank序号:XM_002184476.1)c DNA全长序列,并从基因层面分析了外源诱导子对岩藻黄素生物合成的诱导机制,进一步探究Ptpds的结构和表达特性。结果表明,Ptpds基因cDNA全长2 442 bp,开放阅读框(ORF)为1 773 bp,编码589个氨基酸,并含有一个NAD(P)-binding结构域;蛋白分子结构预测结果表明,三角褐指藻PDS蛋白(PtPDS)分子呈亲水性,含有转运肽、信号肽、跨膜结构域等结构。系统进化树分析显示,PtPDS与新型微藻的PDS蛋白亲缘关系较近,且在所选取的藻类中进化地位较为原始。诱导表达结果表明,Me JA、ASA、AA、ACS等4种诱导子均能促进Ptpds基因的表达,且在4种诱导子处理下,三角褐指藻中的岩藻黄素含量变化与Ptpds基因的表达水平变化呈现高度的一致性,说明Ptpds基因是Me JA、ASA、AA、ACS等诱导子促进三角褐指藻岩藻黄素的生物积累的关键酶基因之一。本研究结果为探究藻类岩藻黄素合成机理提供了依据,并为利用代谢工程手段提高岩藻黄素含量奠定了理论基础。

Fucoxanthin is a kind of new marine drugs which has important medicinal value and exploitable value, phytoene desaturase （PDS） is a key rate limiting enzyme in fucoxanthin biosynthesis pathway of Phaeodactylum tricornutum. Exploring the function ofpds gene is beneficial for better exploitation and utilization of Fucoxanthin. In this study, RT-PCR was used to clone full length cDNA sequence of pds gene （Ptpds, GenBank number： XM 002184476.1）. And the mechanism of exogenous induction to fucoxanthin biosynthesis was analyzed at gene level, to explore the characteristics of structure and expression of Ptpds. The full-length Ptpds gene cDNA was 2 442 bp long, had an open reading frame of 1 773 bp with a NAD（P） - binding Rossmann-like domain and encoded 589 amino acids. The protein prediction results showed that PtPDS was hydrophilic, with transporter peptide, signal peptide and transmembrane domain. After phylogenetic analysis, PtPDS had closed homologous relationship with the PDS protein of Auxenochlorella protothecoides, and had a more primitive evolutionary status among the selected algaes. The results of induced expression showed that four kinds of elicitors （MeJA, ASA, AA, and ACS） could promote the expression of Ptpds gene, expression changes of Ptpds and fucoxanthin content in Phaeodactylum tricornutum under the treatment of four elicitors showed a high consistency, which indicated Ptpds is one of the key genes to promote Phaeodactylum tricornutum fucoxanthin bio-accumulation. This study provided a basis for exploring fucoxanthin synthesis mechanism in algae and also provided a theoretical basis for applying metabolic engineering to improve fucoxanthin content.