山核桃种子脂肪代谢期EST序列的初步分析

Analysis of ESTs associated with oil metabolism in seeds of Carya cathayensis

山核桃Carya cathayensis为重要的油料干果树种,其非同一般的高含油率必定有其特殊的成油机制。为探索其成油机制,在已构建的山核桃脂肪代谢相关c DNA文库基础上,对c DNA进行随机克隆测序,对序列进行拼接、功能注释,基因本体论(gene ontology,GO)分类及基于拟南芥Arabidopsis thaliana的Fun Cat分类,并对与脂肪代谢相关的全长c DNA序列进行蛋白性质分析。结果共得到1 010条山核桃表达序列标签(ESTs),经拼接获得188个编码蛋白质的基因(unigene),其中92个contigs和96个singlets。GO分类将这些unigene分成细胞组分、分子功能和生物过程等3类,并发现各序列编码的基因并不承担单一的功能,有些序列在功能上有重叠;同时参照拟南芥的基因功能分类,将unigene序列在功能上分成9类,得到了143个全长c DNA序列,其中包括14个与脂肪代谢相关的c DNA序列。对12个与脂肪代谢相关的全长c DNA序列进行蛋白性质分析,发现它们均具有磷酸化位点;除油质蛋白外都没有跨膜区域,且不具信号肽结构,为非分泌蛋白,属于某个蛋白家族;不同的油体蛋白具有不同的跨膜区,且均具有信号肽结构,属于Oleosin super family蛋白家族。

Carya cathayensis is an important oil species with dry nuts that are high oil content, for which there must be some special oil-synthesizing mechanism. In order to explore the mechanism, random cloning and se- quencing of cDNAs from a fatty acid metabolism-associated cDNA library, sequence assembly and annotation, Gene Ontology （GO）- and A raSidopsis thaliana-associated MIPS Functional Catalogue （FunCat）-based classi- fication of assembled sequences, and protein analysis of fatty acid metabolism-associated cDNA sequences were performed. A total of 1 010 expressed sequence tags （ESTs） was obtained, based on which 188 unigenes were assembled. There were 92 contigs and 96 singlets among the unigenes, which were classified into categories of cellular component, molecular function, and biological process based on classification of GO and found to over- lap one another in functions. But against MIPS Functional Catalogue in Arabidopsis thaliana, these unigenes were classified into nine categories and 143 full-length cDNAs were obtained, from which 14 cDNA sequences were associated with metabolism of fatty acids. It had been found through proteomic analysis that 12 full-length fatty acid metabolism-related cDNAs had a phosphorylation site; they were all non-secretory proteins with no transmembrane domain and signal peptide except oleosins, belonging to certain protein family; and oleosins had different transmembrane domains and a signal peptide, belonging to a super oleosin family. [Ch, 4 tab. 35 ref.]