Kawaguchi A, Uemura N, Okuda S
J Biochem. 1986 Jun;99(6):1735-42. doi: 10.1093/oxfordjournals.jbchem.a135650.
Curtobacterium pusillum contains 11-cyclohexylundecanoic acid as a major component of cellular fatty acids. A trace amount of 13-cyclohexyltridecanoic acid is also present. Fatty acids other than omega-cyclohexyl fatty acids present are 13-methyltetradecanoic, 12-methyltetradecanoic, n-pentadecanoic, 14-methylpentadecanoic, 13-methylpentadecanoic, n-hexadecanoic, 15-methylhexadecanoic, 14-methylhexadecanoic, and n-heptadecanoic acids. The fatty acid synthetase system of this bacterium was studied. Various 14C-labeled precursors were added to the growth medium and the incorporation of radioactivity into cellular fatty acids was analyzed. Sodium [14C]acetate and [14C]glucose were incorporated into almost all species of cellular fatty acids, the incorporation into 11-cyclohexylundecanoic acid being predominant. [14C]Isoleucine was incorporated into 12-methyltetradecanoic and 14-methylhexadecanoic acids: [14C]leucine into 13-methyltetradecanoic and 15-methylhexadecanoic acids; and [14C]valine into 14-methylpentadecanoic acid. [14C]-Shikimic acid was incorporated almost exclusively into omega-cyclohexyl fatty acids. The fatty acid synthetase activity of the crude enzyme preparation of C. pusillum was reconstituted on the addition of acyl carrier protein. This synthetase system required NADPH and preferentially utilized cyclohexanecarbonyl-CoA as a primer. The system was also able to use branched- and straight-chain acyl-CoAs with 4 to 6 carbon atoms effectively as primers but was unable to use acetyl-CoA. However, if acetyl acyl carrier protein was used as the priming substrate, the system produced straight-chain fatty acids. The results imply that the specificity of the initial acyl-CoA:acyl carrier protein acyltransferase dictates the structure of fatty acids synthesized and that the enzymes catalyzing the subsequent chain-elongation reactions do not have the same specificity restriction.
短小棒杆菌含有11 - 环己基十一烷酸作为细胞脂肪酸的主要成分。还存在微量的13 - 环己基十三烷酸。除了ω - 环己基脂肪酸外，其他脂肪酸有13 - 甲基十四烷酸、12 - 甲基十四烷酸、正十五烷酸、14 - 甲基十五烷酸、13 - 甲基十五烷酸、正十六烷酸、15 - 甲基十六烷酸、14 - 甲基十六烷酸和正十七烷酸。对该细菌的脂肪酸合成酶系统进行了研究。向生长培养基中添加了各种14C标记的前体，并分析了放射性在细胞脂肪酸中的掺入情况。[14C]醋酸钠和[14C]葡萄糖几乎掺入了所有种类的细胞脂肪酸中，其中掺入11 - 环己基十一烷酸的量占主导。[14C]异亮氨酸掺入12 - 甲基十四烷酸和14 - 甲基十六烷酸中；[14C]亮氨酸掺入13 - 甲基十四烷酸和15 - 甲基十六烷酸中；[14C]缬氨酸掺入14 - 甲基十五烷酸中。[14C]莽草酸几乎只掺入ω - 环己基脂肪酸中。添加酰基载体蛋白后重新构建了短小棒杆菌粗酶制剂的脂肪酸合成酶活性。该合成酶系统需要NADPH，并优先利用环己烷羰基 - CoA作为引物。该系统也能够有效地使用具有4至6个碳原子的支链和直链酰基辅酶A作为引物，但不能使用乙酰辅酶A。然而，如果使用乙酰酰基载体蛋白作为引发底物，该系统会产生直链脂肪酸。结果表明，初始的酰基辅酶A：酰基载体蛋白酰基转移酶的特异性决定了合成脂肪酸的结构，并且催化后续链延长反应的酶没有相同的特异性限制。
