Heterologous Expression Of Stearoyl-CoA Desaturase-1Gene In Lactococcus Lactis NZ3900and Overexpression Of Cop-odea Gene In3T3Cells Results In An Increase Of Unsaturated Fatty Acid

SCD is a rate-limiting enzyme in the biosynthesis of monounsaturated fatty acid,and plays a central role in regulation of fatty acid metabolism.The possibility ofheterologous expression of human Stearoyl-CoA Desaturase (SCD1) was investigatedin the current study. The scd1encoding sequence was firstly inserted into thepNZ8149to generate the pNZ8149-scd1expression plasmids. Then we introduced thepNZ8149-scd1construct into the Lactococcus lactis NZ3900to investigate itsenzymic activity. The results showed that heterologous expressed SCD1enzymeresulted in a92%-169%in the C16:1n-7and a53%-127%increase in the C18:1n-7(P<0.05), respectively. The results indicated that the SCD1enzyme was capable ofproducing n-7fatty acids in Lactococcus lactis efficiently. It also suggests that thefatty acid desaturases can be heterologous expressed in Lactococcus lactis to producethe helpful fatty acids.Polyunsaturated fatty acids (PUFAs) cannot be synthesized de novo bymammalian cells as they lack the desaturases that introduce double bonds at the n-3orn-6position of the fatty acids. We generated transgenic3T3cells that carried theCoprinus cinereus Cop-odeA sequence through transfection.The results showedC18:2n-6significantly increased by316%-680%（P <0.01）and47%-60%（P <0.05）in transgenic cells supplemented with10μM and30μM of C18:1n-9, respectively.Meanwhile, the amount of EPA was increase by164%-304%. However, no changesobserved in C18:3n-3fatty acids in transgenic cells supplemented with C18:2n-6andC18:1n-9+C18:2n-6（P>0.05）, respectively. It also suggests that the Cop-odeAdesaturase might have a bifunctional Δ12/ω3desaturation activity.