title: Threonine 286 of fatty acid desaturase 7 is essential for ω-3 fatty acid desaturation in the green microalga Chlamydomonas reinhardtii.
abstract: Omega-3 fatty acid desaturases catalyze the conversion of dienoic fatty acids (C18:2 and C16:2) into trienoic fatty acids (C18:3 and C16:3), accounting for more than 50% of the total fatty acids in higher plants and the green microalga Chlamydomonas reinhardtii. Here, we describe a Thr residue located in the fourth transmembrane domain of fatty acid desaturase 7 (FAD7) that is essential for the biosynthesis of ω-3 fatty acids in C. reinhardtii. The ω-3 fatty acid deficiency in strain CC-620, which contains a putative missense mutation at Thr286 of CrFAD7, was recovered by the overexpression of CC-125 CrFAD7. A Ser substitution in position 286 was able to partially complement the phenotype of the ω-3 fatty acid deficiency, but other substitution variants, such as Tyr, His, Cys, and Gly, failed to do so. Prediction of the phosphorylation target site revealed that Thr286 may be phosphorylated. Analysis of the structural conformation of CC-620 CrFAD7 via topology prediction (and bends in the helix) shows that this missense mutation may collapse the catalytic structure of CrFAD7. Taken together, this study suggests that Thr286 is essential for the maintaining the catalytic structure of CrFAD7.
authors.affiliation: Sustainable Bioresource Center, Korea Institute of Bioscience and Biotechnology Daejeon, South Korea.
authors.forename: Jong-Min
authors.initials: JM
authors.lastname: Lim
authors.affiliation: Sustainable Bioresource Center, Korea Institute of Bioscience and Biotechnology Daejeon, South Korea.
authors.forename: Jayaraman
authors.initials: J
authors.lastname: Vikramathithan
authors.affiliation: Sustainable Bioresource Center, Korea Institute of Bioscience and Biotechnology Daejeon, South Korea ; Department of Biological Science, Chungnam National University Daejeon, South Korea.
authors.forename: Kwon
authors.initials: K
authors.lastname: Hwangbo
authors.affiliation: Advanced Radiation Technology Institute - Korea Atomic Energy Research Institute Jeonbuk, South Korea.
authors.forename: Joon-Woo
authors.initials: JW
authors.lastname: Ahn
authors.affiliation: Department of Biological Science, Chungnam National University Daejeon, South Korea.
authors.forename: Youn-Il
authors.initials: YI
authors.lastname: Park
authors.affiliation: Department of Biology Education, Chonnam National University South Korea.
authors.forename: Dong-Woog
authors.initials: DW
authors.lastname: Choi
authors.affiliation: Sustainable Bioresource Center, Korea Institute of Bioscience and Biotechnology Daejeon, South Korea.
authors.forename: Won-Joong
authors.initials: WJ
authors.lastname: Jeong
keywords: Chlamydomonas reinhardtii; CrFAD7; Thr286; fatty acid desaturase; topology