Ma Chunyan, Wu Linzhuan, Dai Jianlu, Zhou Hongxia, Li Jingyan, Sun Xiaochun, Zhang Kan, Xia Huanzhang, Wang Yiguang
Key Laboratory of Biotechnology of Antibiotics, Ministry of Health, Institute of Medicinal Biotechnolgy, CAMS & PUMC, Beijing 100050, China.
Sheng Wu Gong Cheng Xue Bao. 2008 Dec;24(12):2086-92.
Spiramycin and midecamycin are 16-membered macrolide antibiotics with very similar chemical structures. Spiramycin has three components, namely spiramycin I, II and III. Spiramycin II and III are, respectively, the O-acetyl and propionyl derivatives at C3-hydroxyl group of spiramycin I. Midecamycin has four components, and the C3-hydroxyl group of midecamycin is all O-propionylated. The enzyme adding acyl group(s) at the C3-hydroxyl group during the biosynthesis of spiramycin and midecamycin is 3-O-acyltransferase. The 3-O-acyltransferases for spiramycin and midecamycin are also very similar, and presume to function when exchanged. To explore whether the 3-O-acyltransferase for midecamycin biosynthesis hold still the character of selective and efficient propionylation for spiramycin I at its C3-hydroxyl group, we inserted mdmB, the 3-O-acyltransferase gene from Streptomyces mycarofaciens ATCC 21454 for midecamycin biosynthesis, into a mutant strain of S. spiramyceticus F21, in which the 3-O-acyltransferase gene for spiramycin biosynthesis, sspA, was deleted; and the mdmB was integrated exactly into the chromosomal site where the sspA was deleted. We name this "hybrid" strain as SP-mdmB. HPLC analysis of the spiramycin produced by SP-mdmB showed that spiramycin I was still the major component, although the relative proportions of both spiramycin II and III increased significantly. We thus conclude that MdmB from Streptomyces mycarofaciens ATCC 21454 for midecamyicn biosynthesis do not hold the character of selective and efficient propionylation for spiramycin I within S. spiramyceticus F21, and this character is possibly limited in Streptomyces mycarofaciens ATCC 21454 for midecamycin biosynthesis.
螺旋霉素和麦迪霉素是化学结构非常相似的16元大环内酯类抗生素。螺旋霉素有三个组分，即螺旋霉素I、II和III。螺旋霉素II和III分别是螺旋霉素I C3-羟基上的O-乙酰基和丙酰基衍生物。麦迪霉素有四个组分，且麦迪霉素的C3-羟基均被O-丙酰化。在螺旋霉素和麦迪霉素生物合成过程中，在C3-羟基上添加酰基的酶是3-O-酰基转移酶。螺旋霉素和麦迪霉素的3-O-酰基转移酶也非常相似，推测可以互换发挥作用。为了探究用于麦迪霉素生物合成的3-O-酰基转移酶对螺旋霉素I的C3-羟基是否仍具有选择性高效丙酰化的特性，我们将来自生米卡链霉菌ATCC 21454的用于麦迪霉素生物合成的3-O-酰基转移酶基因mdmB插入到螺旋链霉菌F21的一个突变株中，该突变株中用于螺旋霉素生物合成的3-O-酰基转移酶基因sspA已缺失；并且mdmB正好整合到sspA缺失的染色体位点上。我们将这个“杂交”菌株命名为SP-mdmB。对SP-mdmB产生的螺旋霉素进行HPLC分析表明，尽管螺旋霉素II和III的相对比例显著增加，但螺旋霉素I仍然是主要组分。因此我们得出结论，来自生米卡链霉菌ATCC 21454的用于麦迪霉素生物合成的MdmB在螺旋链霉菌F21内对螺旋霉素I不具有选择性高效丙酰化的特性，并且这种特性可能局限于用于麦迪霉素生物合成的生米卡链霉菌ATCC 21454中。
