9.A.76. The Omega3 Fatty Acid Desaturase 3/Putative Transporter (FAD3) Family FAD3-like proteins have been known to be fatty acid desaturases for many years (Pugh and Kates 1979). Oilseed crop oils contain a variety of unsaturated fatty acids that are synthesized and regulated by fatty acid desaturases (FADs). Soltani Gishini et al. 2019 examined 14 FAD3 (omega3 desaturase) protein sequences from oilseeds indicating a close relationship between Brassica napus and Camelina sativa, as well as between Salvia hispanica and Perilla frutescens FAD3s, due to a high similarity in codon preferences in codon usage clusters and the phylogenetic tree. The cis-acting elements showed that the seed-specific promoter region of BnFAD3 contains the critical conserved boxes (HSE and ABRE), which are involved in responsiveness to heat stress and abscisic acid. These boxes may increase cold acclimation as well as tolerance to drought and high salinity. Omega(omega)3 desaturases contain a Skn-1 motif which is a cis-acting regulatory element required for endosperm development. It was found that BnFAD3 is a transmembrane protein, probably wit h6 TMSs, that can convert omega6 to omega3 fatty acids and may simultaneously act as a potassium ion channel in the ER.
References:
Pugh, E.L. and M. Kates. (1979). Membrane-bound phospholipid desaturases. Lipids 14: 159-165.
Soltani Gishini, M.F., A. Zebarjadi, M. Abdoli-Nasab, M. Jalali Javaran, D. Kahrizi, and D. Hildebrand. (2019). Endoplasmic reticulum retention signaling and transmembrane channel proteins predicted for oilseed ω3 fatty acid desaturase 3 (FAD3) genes. Funct Integr Genomics. [Epub: Ahead of Print]
Examples:
TC#	Name	Organismal Type	Example
9.A.76.1.1	*Omega3 fatty acid desaturase 3 (FAD3) of 383 aas and 6 probable TMSs. It may function both as a desaturase and a K⁺ channel (Soltani Gishini et al.* 2019).**		FAD3 of Brassica napus

9.A.76.1.10	Fatty acid desaturase of 344 aas and 6 TMSs in a 3 + 3 TMS arrangement.		Fatty acid desaturase of Candidatus Poseidoniales archaeon

9.A.76.1.11	Uncharacterized protein of 245 aas and 6 TMSs in a 2 + 1 + 1 + 2 TMS arrangement.		UP of Phytophthora rubi

9.A.76.1.12	Acyl-CoA desaturase of 352 aas and 6 TMSs.		Desaturase of Chloroflexi bacterium

9.A.76.1.2	Delta(12) fatty acid desaturase of 435 aas and 6 TMSs in a 3 + 3 TMS arrangement.		Desaturase of Candida viswanathii

9.A.76.1.3	Fatty acid desaturase of 405 aas and 6 TMSs in a 3 + 3 TMS arrangement.		Desaturase of Prochlorococcus marinus

9.A.76.1.4	Oleate desaturase of 419 aas and 6 putative TMSs in a 3 + 3 TMS arrangement.		Oleate deasturase of Trypanosoma rangeli

9.A.76.1.5	Fatty acid desaturase of 371 aas and 6 TMSs in a 3 + 3 TMS arrangement.		Fatty acid desaturase of Tetrahymena thermophila

9.A.76.1.6	Fatty acid desaturase of 365 aas and 6 TMSs in a 3 + 3 TMS arrangement.		Fatty acid desaturase of Hyphomonadaceae bacterium BRH_c29

9.A.76.1.7	Omega-3 fatty acid desaturase-like B protein with 388 aas and 6 TMSs in a 3 + 3 TMS arrangement		Desaturase of Platynereis dumerilii

9.A.76.1.8	Fatty acid desaturase of 339 aas and 6 TMSs in a 2 + 1 + 1 + 2 TMS arrangement.		Fatty acid desaturase of Bacillus salsus

9.A.76.1.9	Fatty acid desaturase of 366 aas and 6 TM		Fatty acid desaturase of Empedobacter haloabium