Southern Cross Plant Science, Southern Cross University, Lismore, NSW, Australia.
Grasslands Research Centre, AgResearch Ltd, Palmerston North, New Zealand.
Clin Exp Allergy. 2020 Jul;50(7):848-868. doi: 10.1111/cea.13612. Epub 2020 May 6.
Brassica rapeseed crops contain high concentrations of oil in the seed. The remaining meal, following oil extraction, has a high protein content, but is of low value due to the presence of high amounts of napin seed storage proteins. These 2S albumin-like proteins are difficult to digest and have been identified as major allergens in humans.
To comprehensively characterize the napin gene (NG) family in Brassica rapa and to gain an understanding of the structural basis of allergenicity of the expressed proteins.
To identify candidate napin genes in B rapa, 2S albumin-like napin genes of Arabidopsis thaliana were used as query sequences to search for similarity against the B rapa var. pekinensis Chiifu-401 v2 and the var. trilocularis R-o-18 v1.5 genomes. Multiple sequence alignment (MSA) and epitope modelling was carried out to determine structural and evolutionary relationships of NGs and their potential allergenicity.
Four candidate napin genes in R-o-18 and ten in Chiifu-401 were identified with high sequence similarity to A thaliana napin genes. Multiple sequence alignment revealed strong conservation among the candidate genes. An epitope survey indicated high conservation of allergenic epitope motifs with known 2S albumin-like allergens.
Napin is thought to be responsible for a high prevalence of food allergies. Characterization of the napin gene family in B rapa will give important insight into the protein structure, and epitope modelling will help to advance studies into allergenicity including the development of precise diagnostic screenings and therapies for this potential food allergy as well as the possible manipulation of napin levels in the seed by gene editing technology.
油菜籽作物的种子含有高浓度的油。油提取后剩余的饼粕蛋白质含量高，但由于含有大量的 napin 种子贮藏蛋白，价值较低。这些 2S 白蛋白样蛋白难以消化，已被确定为人类的主要过敏原。
全面描述芸薹属油菜 napin 基因（NG）家族，并了解表达蛋白变应原性的结构基础。
为了鉴定芸薹属油菜中的候选 napin 基因，使用拟南芥 2S 白蛋白样 napin 基因作为查询序列，在 Brassica rapa var. pekinensis Chiifu-401 v2 和 var. trilocularis R-o-18 v1.5 基因组中搜索相似性。进行多序列比对（MSA）和表位建模，以确定 NG 的结构和进化关系及其潜在的变应原性。
在 R-o-18 中鉴定出 4 个候选 napin 基因，在 Chiifu-401 中鉴定出 10 个候选 napin 基因，它们与拟南芥 napin 基因具有高度的序列相似性。多序列比对显示候选基因之间具有很强的保守性。表位调查表明，与已知的 2S 白蛋白样过敏原相比，变应原表位模体具有高度的保守性。
napin 被认为是导致食物过敏高发的原因。对芸薹属油菜 napin 基因家族的特征描述将为蛋白质结构提供重要的见解，表位建模将有助于深入研究变应原性，包括开发针对这种潜在食物过敏的精确诊断筛查和治疗方法，以及通过基因编辑技术对种子中 napin 水平进行可能的操纵。
