Determination of functional domains and topology model of membrane-bound Delta-6 desaturase enzyme from Mortierella alpina

Desaturase enzymes (EC: 1.14.19.3) catalyze dehydrogenation reactions and creates a double bond in the fatty acid chains. These enzymes classified into two groups, soluble and membrane each with different consensus motifs. Despite the Delta-6 desaturase is a key enzyme in the biosynthesis of unsaturated fatty acids but due to lack of structural information of membrane-bound desaturase, it's three-dimensional and crystal structure has not been determined. Mortierella alpina is a rich source for production of unsaturated fatty acid arachidonic and has an active Delta-6 desaturases enzyme. The aim of this study was obtain encoding sequences of Delta-6 desaturase gene, and determination of functional domains using comparative analysis and molecular model and propose a membrane topology model for this enzyme. Thus, after extraction of total RNA and cDNA synthesis using gene specific primers, PCR product was cloned into pBlueScriptSK vector and then sequenced. Based on bioinformatics analysis by Swissmodel, Predict and Phobius servers presence of functional domains cytochrome b5 carrying motif (HPGG), three His-box motifs and transmembrane regions were identified. Then we proposed a membrane topology model for the Delta-6 desaturase enzyme.