FIG 2.
(a) Proposed route for alkene biosynthesis in Synechococcus sp. strain PCC 7002. DesE is required to place a double bond at the Δ9 position of the C14:0 acyl-ACP substrate. The product subsequently is elongated to a C18:1(Δ13) acyl-ACP that would serve as the precursor for 1,14-nonadecadiene biosynthesis by Ols. (b) Comparison of the fatty acid profiles of Synechococcus sp. strain PCC 7002 and mutants. Feeding of the C14:1(Δ9) fatty acid to the wild-type strain and overexpression of desE in the Δols strain resulted in the formation of the C16:1(Δ11) fatty acid (retention time, 15.2 min) and the C18:1(Δ13) fatty acid (retention time, 19.9 min). Attempts to chemically complement the ΔdesE mutant with C14:1(Δ9) fatty acid failed, as did attempts to chemically complement the Δols mutant with 1-nonadecene.