cDNA Clones Encoding beta-Ketoacyl-Acyl Carrier Protein Synthase III from Cuphea wrightii

摘要

KASIII catalyzes the condensation of acetyl-CoA with malonyl-acyl carrier protein in dissociated (type II) fatty acid synthase systems, such as those found in plant and bacterial cells. Initially identified as a cerulenin-resistant condensing enzyme (Jackowski and Rock, 1987; Jaworski et al. 1989; Clough et al. 1992), genes encoding this protein have been identified in Escherichia coli (Tsay et al., 1992), a red alga (Reith 1993), and spinach (Tai and Jaworski, 1993). Evidence that acetyl-CoA is themajor primer of fatty acid biosynthesis in spinach has recently been presented (Jaworski et al. 1993), and a role for this enzyme in regulation of fatty acid biosynthesis in bacteria has been suggested (Jackowski and Rock, 1987). We are interested in whether the KASIII reaction represents a regulatory point in the rapid lipid biosynthesis observed in developing embryos of the oilseed plant Cuphea (Slabas et al., 1982). Here we report the sequence of two cDNA clones encoding KASIII in Cuphea wrightii (Table I).