title: Isolation and characterization of a seed-specific isoform of microsomal omega-6 fatty acid desaturase gene (FAD2-1B) from soybean.
abstract: In plants, the endoplasmic reticulum (ER)-associated oleate desaturase (FAD2) is the key enzyme responsible for the production of linoleic acid in non-photosynthetic tissues. In this study, we report the characterization of a seed-specific isoform of microsomal omega-6 fatty acid desaturase gene (FAD2-1B) sharing high sequence similarity with FAD2-1 from soybean. Several potential promoter elements including seed-specific motifs are found in the 5'-flanking region of FAD2-1B gene. The ORF of FAD2-1B is 1161 bp long and encodes a protein of 387 amino acids. This deduced protein holds three histidine boxes and four putative membrane-spanning helices, and possesses a signal for endoplasmic reticulum retention at C-terminal. Yeast cells transformed with the plasmid construct containing soybean FAD2-1B accumulate an appreciable amount of linoleic acid (18:2), normally not present in wild-type yeast cells, indicating that the cloned gene encodes a functional FAD2 enzyme. Both semi-quantitative RT-PCR and in silico analysis show that FAD2-1B gene is specifically expressed in developing seeds of soybean.
authors.affiliation: National Center Laboratory of Crop Genetics and Germplasm Enhancement, National Center for Soybean Improvement, Nanjing Agricultural University, Nanjing 210095, People's Republic of China.
authors.forename: Lingyong
authors.initials: L
authors.lastname: Li
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Wang
authors.forename: Junyi
authors.initials: J
authors.lastname: Gai
authors.forename: Deyue
authors.initials: D
authors.lastname: Yu
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D044943:Fatty Acid Desaturases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D043371:Fatty Acids, Omega-6 / Q000378:metabolism*; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D008861:Microsomes / Q000201:enzymology*; D008969:Molecular Sequence Data; D012639:Seeds / Q000201:enzymology / Q000235:genetics*; D017422:Sequence Analysis, DNA; D020539:Sequence Analysis, Protein; D013025:Glycine max / Q000201:enzymology / Q000235:genetics*
chemical_list: D043371:Fatty Acids, Omega-6; D007527:Isoenzymes; D044943:Fatty Acid Desaturases; C040448:delta-12 fatty acid desaturase