Isolation and characterization of an enoyl-acyl carrier protein reductase gene from microalga Isochrysis galbana

In most bacteria, plants and algae, fatty acid biosynthesis is catalyzed by a group of freely dissociable proteins known as the type II fatty acid synthase （FAS II） system. In the FAS II system, enoyl- acyl carrier protein reductase （ENR） acts as a determinant for completing the cycles of fatty acid elongation. In this study, the cDNA sequence of ENR, designated as IgENR, was isolated from the microalga lsochrysis galbana CCMM5001. RACE （rapid amplification of cDNA ends） was used to isolate the full-length cDNA oflgENR （1 503 bp）, which contains an open reading frame （ORF） of 1 044 bp and encodes a protein of 347 amino acids. The genomic DNA sequence oflgENR is interrupted by four introns. The putative amino acid sequence is homologous to the ENRs of seed plants and algae, and they contain common coenzyme- binding sites and active site motifs. Under different stress conditions, real-time quantitative polymerase chain reaction （RT-qPCR） showed the expression oflgENR was upregulated by high temperature （35℃）, and downregulated by depleted nitrogen （0 mol/L）. To clarify the mechanism of lipids accumulating lipids, other genes involved in lipids accumulation should be studied.