Isolation and Functional Characterisation of the Genes Encoding Δ~8-Sphingolipid Desaturase from Brassica rapa  

作　　者：Shu-Fen Li Li-Ying Song Wei-Bo Yin yu-Hong Chen Liang Chen Ji-Lin Li Richard R.-C.Wang Zan-Min Hu 

机构地区：[1]Institute of Genetics and Developmental Biology,Chinese Academy of Sciences,Beijing 100101,China [2]Graduate University of Chinese Academy of Sciences,Beijing 100049,China [3]Biological College,Harbin Normal University,Harbin 150080,China [4]USDA-ARS,FRRL,Utah State University,Logan,UT 84322-6300,USA

出　　处：《Journal of Genetics and Genomics》2012年第1期47-59,共13页遗传学报（英文版）

基　　金：supported by the National High-tech R&D Program(863 Program,No.2006AA10A113) of the Ministry of Science and Technology of China;the projects of Ministry of Agriculture of China for Transgenic Research (Nos.2009ZX08009-098B and 2008ZX08009-003)

摘　　要：8-Sphingolipid desaturase is the key enzyme that catalyses desaturation at the C8 position of the long-chain base of sphingolipids in higher plants. There have been no previous studies on the genes encoding AS-sphingolipid desaturases in Brassica rapa. In this study, four genes encoding AS-sphingolipid desaturases from B. rapa were isolated and characterised. Phylogenetic analyses indicated that these genes could be divided into two groups： BrD8A, BrD8C and BrD8D in group I, and BrD8B in group II. The two groups of genes diverged before the separation of Arabidopsis and Brassica. Though the four genes shared a high sequence similarity, and their coding desaturases all located in endoplasmic reticulum, they exhibited distinct expression patterns. Heterologous expression in Saccharomyces cerevisiae revealed that BrD8A/B/C/D were functionally diverse AS-sphingolipid desaturases that catalyse different ratios of the two products 8（Z）- and 8（E）-C18-phytosphingenine. The aluminium tolerance of transgenic yeasts expressing BrD8A/B/C/D was enhanced compared with that of control cells. Expression of BrD8A in Arabidopsis changed the ratio of 8（Z）：8（E）-C 18-phytosphingenine in transgenic plants. The information reported here provides new insights into the biochemical functional diversity and evolutionary relationship of AS-sphingolipid desaturase in plants and lays a foundation for further investigation of the mechanism of 8（Z）- and 8（E）-C18- phytosphingenine biosynthesis.△8-Sphingolipid desaturase is the key enzyme that catalyses desaturation at the C8 position of the long-chain base of sphingolipids in higher plants. There have been no previous studies on the genes encoding AS-sphingolipid desaturases in Brassica rapa. In this study, four genes encoding AS-sphingolipid desaturases from B. rapa were isolated and characterised. Phylogenetic analyses indicated that these genes could be divided into two groups： BrD8A, BrD8C and BrD8D in group I, and BrD8B in group II. The two groups of genes diverged before the separation of Arabidopsis and Brassica. Though the four genes shared a high sequence similarity, and their coding desaturases all located in endoplasmic reticulum, they exhibited distinct expression patterns. Heterologous expression in Saccharomyces cerevisiae revealed that BrD8A/B/C/D were functionally diverse AS-sphingolipid desaturases that catalyse different ratios of the two products 8（Z）- and 8（E）-C18-phytosphingenine. The aluminium tolerance of transgenic yeasts expressing BrD8A/B/C/D was enhanced compared with that of control cells. Expression of BrD8A in Arabidopsis changed the ratio of 8（Z）：8（E）-C 18-phytosphingenine in transgenic plants. The information reported here provides new insights into the biochemical functional diversity and evolutionary relationship of AS-sphingolipid desaturase in plants and lays a foundation for further investigation of the mechanism of 8（Z）- and 8（E）-C18- phytosphingenine biosynthesis.

关 键 词：△8-Sphingolipid desaturase Biochemical functional diversity Brassica rapa Expression pattern Long-chain base （LCB） 

分 类 号：Q987[生物学—遗传学] S511.03[生物学—人类学]