Horton Catherine Emily, Huang Ke-Xue, Bennett George N, Rudolph Frederick B
Department of Biochemistry and Cell Biology, Rice University, 6100 S Main Street, MS140, Houston, TX 77005, USA.
J Ind Microbiol Biotechnol. 2003 Jul;30(7):427-32. doi: 10.1007/s10295-003-0070-0. Epub 2003 Jul 9.
Esters are formed by the condensation of acids with alcohols. The esters isoamyl acetate and butyl butyrate are used for food and beverage flavorings. Alcohol acetyltransferase is one enzyme responsible for the production of esters from acetyl-CoA and different alcohol substrates. The genes ATF1 and ATF2, encoding alcohol acetyltransferases from the yeast Saccharomyces cerevisiae have been sequenced and characterized. The production of acids and alcohols in mass quantities by the industrially important Clostridium acetobutylicum makes it a potential organism for exploitation of alcohol acetyltransferase activity. This report focuses on the heterologous expression of the alcohol acetyltransferases in Escherichia coli and C. acetobutylicum. ATF1 and ATF2 were cloned and expressed in E. coli and ATF2 was expressed in C. acetobutylicum. Isoamyl acetate production from the substrate isoamyl alcohol in E. coli and C. acetobutylicum cultures was determined by head-space gas analysis. Alcohol acetyltransferase I produced more than twice as much isoamyl acetate as alcohol acetyltransferase II when expressed from a high-copy expression vector. The effect of substrate levels on ester production was explored in the two bacterial hosts to demonstrate the efficacy of utilizing ATF1 and ATF2 in bacteria for ester production.
酯是由酸与醇缩合形成的。乙酸异戊酯和丁酸丁酯这两种酯类用于食品和饮料调味。乙醇乙酰转移酶是一种负责从乙酰辅酶A和不同醇底物生成酯类的酶。已对编码酿酒酵母乙醇乙酰转移酶的基因ATF1和ATF2进行了测序和表征。具有重要工业价值的丙酮丁醇梭菌能够大量生产酸和醇，这使其成为利用乙醇乙酰转移酶活性的潜在微生物。本报告重点关注乙醇乙酰转移酶在大肠杆菌和丙酮丁醇梭菌中的异源表达。ATF1和ATF2被克隆并在大肠杆菌中表达，ATF2在丙酮丁醇梭菌中表达。通过顶空气体分析测定了大肠杆菌和丙酮丁醇梭菌培养物中由底物异戊醇生成乙酸异戊酯的情况。当从高拷贝表达载体表达时，乙醇乙酰转移酶I产生的乙酸异戊酯比乙醇乙酰转移酶II多两倍以上。在两种细菌宿主中研究了底物水平对酯生成的影响，以证明在细菌中利用ATF1和ATF2进行酯生产的有效性。
