Arisawa A, Kawamura N, Narita T, Kojima I, Okamura K, Tsunekawa H, Yoshioka T, Okamoto R
Merican Corporation, Central Research Laboratories, Kanagawa, Japan.
J Antibiot (Tokyo). 1996 Apr;49(4):349-54. doi: 10.7164/antibiotics.49.349.
A tylosin-producer, Streptomyces fradiae, was transformed with plasmids carrying genes from Streptomyces thermotolerans that are involved in acyl modification of macrolide antibiotics. A transformant with pMAB3, in which macrolide 4"-O-acyltransferase gene (acyB1) and its regulatory gene (acyB2) are subcloned, produced several types of 4"-O-acyltylosins. A transformant with pAB11 delta EH containing macrolide 3-O-acyltransferase gene (acyA) in addition to the above two genes produced 3-O-acetyltylosin and 3-O-acetyl-4"-O-acyltylosins. Among the products of the latter transformant, 3-O-acetyl-4"-O-isovaleryltylosin (AIV) was detected as a minor component. When L-leucine, a precursor of isovaleryl-CoA, was added to the medium at the late stage of the fermentation, AIV content among the total macrolides increased ten-fold and AIV became a main product. This fact suggests that a high level of endogenous isovaleryl-CoA may be essential for the selective production of AIV by S. fradiae carrying pAB11 delta EH.
一株泰乐菌素产生菌，耐热链霉菌（Streptomyces fradiae），用携带来自耐热链霉菌中参与大环内酯类抗生素酰基修饰基因的质粒进行转化。携带pMAB3的转化子，其中大环内酯4″-O-酰基转移酶基因（acyB1）及其调控基因（acyB2）被亚克隆，产生了几种类型的4″-O-酰基泰乐菌素。携带pAB11 delta EH的转化子除了上述两个基因外还含有大环内酯3-O-酰基转移酶基因（acyA），产生了3-O-乙酰基泰乐菌素和3-O-乙酰基-4″-O-酰基泰乐菌素。在后者转化子的产物中，检测到3-O-乙酰基-4″-O-异戊酰基泰乐菌素（AIV）作为次要成分。当在发酵后期将异戊酰辅酶A的前体L-亮氨酸添加到培养基中时，总大环内酯中AIV的含量增加了十倍，并且AIV成为主要产物。这一事实表明，高水平的内源性异戊酰辅酶A对于携带pAB11 delta EH的弗氏链霉菌选择性生产AIV可能是必不可少的。
