Faust L R, Connor J A, Roof D M, Hoch J A, Babior B M
Department of Molecular and Experimental Medicine, Research Institute of Scripps Clinic, La Jolla, California 92037.
J Biol Chem. 1990 Jul 25;265(21):12462-6.
Ethanolamine ammonia-lyase is a bacterial enzyme that catalyzes the adenosylcobalamin-dependent conversion of certain vicinal amino alcohols to oxo compounds and ammonia. Studies of ethanolamine ammonia-lyase from Clostridium sp. and Escherichia coli have suggested that the enzyme is a heterodimer composed of subunits of Mr approximately 55,000 and 35,000. Using a partial Sau3A Salmonella typhimurium library ligated into pBR328 and selecting by complementation of a mutant lacking ethanolamine ammonia-lyase activity, we have cloned the genes for the 2 subunits of the S. typhimurium enzyme. The genes were localized to a 6.5-kilobase fragment of S. typhimurium DNA, from which they could be expressed in E. coli under noninducing conditions. Sequencing of a 2526-base pair portion of this 6.5-kilobase DNA fragment revealed two open reading frames separated by 21 base pairs. The open reading frames encoded proteins of 452 and 286 residues whose derived N-terminal sequences were identical to the N-terminal sequences of the 2 subunits of the E. coli ethanolamine ammonia-lyase, except that residue 16 of the large subunit was asparagine in the E. coli sequence and aspartic acid in the S. typhimurium sequence.
乙醇胺氨裂解酶是一种细菌酶，可催化某些邻位氨基醇在腺苷钴胺素依赖下转化为氧代化合物和氨。对来自梭菌属和大肠杆菌的乙醇胺氨裂解酶的研究表明，该酶是一种异源二聚体，由分子量约为55,000和35,000的亚基组成。利用连接到pBR328中的部分Sau3A鼠伤寒沙门氏菌文库，并通过对缺乏乙醇胺氨裂解酶活性的突变体进行互补筛选，我们克隆了鼠伤寒沙门氏菌酶的两个亚基的基因。这些基因定位于鼠伤寒沙门氏菌DNA的一个6.5千碱基片段上，在非诱导条件下可在大肠杆菌中从该片段表达。对这个6.5千碱基DNA片段的2526碱基对部分进行测序，发现了两个由21个碱基对隔开的开放阅读框。这些开放阅读框编码了452和286个残基的蛋白质，其推导的N端序列与大肠杆菌乙醇胺氨裂解酶的两个亚基的N端序列相同，只是大亚基的第16位残基在大肠杆菌序列中是天冬酰胺，在鼠伤寒沙门氏菌序列中是天冬氨酸。
