Substrate Specificity of Acyl-Lipid Δ9-Desaturase from Cyanobacterium sp. IPPAS B-1200, a Cyanobacterium with Unique Fatty Acid Composition

Abstract

Cyanobacterium sp. IPPAS B-1200 is characterized by a high content of rare fatty acids (FAs), both myristic (14:0–30%) and myristoleic (14:1Δ9–10%) in the membrane lipids. Thus, short-chain FAs reach 40% of the sum of all FAs in cells, which is unusual for Cyanobacteria. Monounsaturated palmitoleic acids (16:1Δ9) also reach 40% of the sum of the FAs. We determined the complete nucleotide sequence of the genome of this cyanobacterium and found the only gene for the acyl-lipid Δ9-desaturase, desC1. We cloned this gene and characterized its specificity to the length of the substrate using heterologous expression in Escheriсhia coli. The results show that DesC1 nonspecifically generates olefin bond in FAs with a length of 14, 16, and 18 carbon atoms. This finding confirms that all monoesterifed FAs in Cyanobacterium sp. IPPAS B-1200 are generated by one acyl-lipid Δ9-desaturase.