In Silico Analysis of Fatty Acid Desaturases Structures in Camelina sativa, and Functional Evaluation of Csafad7 and Csafad8 on Seed Oil Formation and Seed Morphology.

Nadia Raboanatahiry,Longjiang Yu,Jianjie He,Yongtai Yin,Maoteng Li,Kang Chen

doi:10.3390/ijms221910857

Nadia Raboanatahiry, Longjiang Yu + Show 4 more

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https://doi.org/10.3390/ijms221910857

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Abstract

Fatty acid desaturases add a second bond into a single bond of carbon atoms in fatty acid chains, resulting in an unsaturated bond between the two carbons. They are classified into soluble and membrane-bound desaturases, according to their structure, subcellular location, and function. The orthologous genes in Camelina sativa were identified and analyzed, and a total of 62 desaturase genes were identified. It was revealed that they had the common fatty acid desaturase domain, which has evolved separately, and the proteins of the same family also originated from the same ancestry. A mix of conserved, gained, or lost intron structure was obvious. Besides, conserved histidine motifs were found in each family, and transmembrane domains were exclusively revealed in the membrane-bound desaturases. The expression profile analysis of C. sativa desaturases revealed an increase in young leaves, seeds, and flowers. C. sativa ω3-fatty acid desaturases CsaFAD7 and CsaDAF8 were cloned and the subcellular localization analysis showed their location in the chloroplast. They were transferred into Arabidopsis thaliana to obtain transgenic lines. It was revealed that the ω3-fatty acid desaturase could increase the C18:3 level at the expense of C18:2, but decreases in oil content and seed weight, and wrinkled phenotypes were observed in transgenic CsaFAD7 lines, while no significant change was observed in transgenic CsaFAD8 lines in comparison to the wild-type. These findings gave insights into the characteristics of desaturase genes, which could provide an excellent basis for further investigation for C. sativa improvement, and overexpression of ω3-fatty acid desaturases in seeds could be useful in genetic engineering strategies, which are aimed at modifying the fatty acid composition of seed oil.

Highlights

Fatty acid desaturases are enzymes, which turn a single bond of carbon atom into a double bond at specific positions of fatty acid hydrocarbon chains, resulting in an unsaturated bond between the two carbon atoms [1,2,3,4]
A total of 62 fatty acid desaturase genes were found in CamRegBase during the current study, which was more numerous than the 24 genes found in NCBI [47]
Some gene copies in C. sativa were longer than in A. thaliana—probably due to some errors, so this needs some revision—but they still had the FA_desaturase domain, which is common in fatty acid desaturases

Summary

Introduction

Fatty acid desaturases are enzymes, which turn a single bond of carbon atom into a double bond at specific positions of fatty acid hydrocarbon chains, resulting in an unsaturated bond between the two carbon atoms [1,2,3,4]. Membrane-bound desaturases are located in both plastid and ER, and they work on the desaturation of fatty acids, which are either turned into acyl-CoA via esterification or are bound to the glycerol part of glycerolipids [3]. Those membrane-bound desaturases are responsible for membrane lipid alteration and adjustment [8]. They include the ADS family (Acyl-lipid ∆9-desaturase) [9], the DES family (sphingolipids ∆4-desaturase) [10], and the FAD family. The FAD family includes the ∆12-desaturase/ω6-fatty acid desaturases FAD2 [11] and FAD6 [12], the

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