Identification and characterization of a novel Δ6-fatty acid desaturase gene from Rhizopus arrhizus

AbstractA cDNA sequence putatively encoding a Δ6-fatty acid desaturase was isolated from Rhizopus arrhizus using reverse transcription polymerase chain reaction and rapid amplification of cDNA ends methods. Sequence analysis indicated that this cDNA sequence had an open reading frame of 1377 bp encoding 458 amino acids of 52 kDa. The deduced amino acid sequence showed high similarity to those of fungal Δ6-fatty acid desaturases which comprised the characteristics of membrane-bound desaturases, including three conserved histidine-rich motifs and hydropathy profile. A cytochrome b5-like domain was observed at the N-terminus. To elucidate the function of this novel putative desaturase, the coding sequence was expressed heterologously in Saccharomyces cerevisiae strain INVScl. The result demonstrated that the coding product of the sequence exhibited Δ6-fatty acid desaturase activity by the accumulation of γ-linolenic acid