Regulatory and biosynthetic effects of the bkd gene clusters on the production of daptomycin and its analogs A21978C1-3
Regulatory and biosynthetic effects of the bkd gene clusters on the production of daptomycin and its analogs A21978C1-3
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bkd基因簇对达托霉素及其类似物A21978C(1-3)生产的调控和生物合成作用
DOI：
10.1007/s10295-018-2011-y
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发表时间：
2018-04-01
影响因子：
3.4
通讯作者：
Li, Yong-Quan
中科院分区：
文献类型：
--
作者：
Luo, Shuai;Chen, Xin-Ai;Li, Yong-Quan
达托霉素是由玫瑰孢链霉菌在酸性肽复合物A21978 C中产生的环状脂肽抗生素。在该复合物中，A21978 C（1-3）是最丰富的，并含有支链脂肪酰基，而达托霉素具有直链癸酰基。链霉菌bkd基因簇编码的支链α-酮酸脱氢酶复合物（BCDH复合物）负责将支链氨基酸转化为支链脂肪酸的早期步骤。在达托霉素工业生产商S. roseosporus L30中，bkd基因簇的两个等位基因bkdA 1B 1C 1/bkdA 2B 2C 2和位于bkdA 2B 2C 2上游的调控基因bkdR被鉴定。我们发现，BkdR正调控bkdA 2B 2C 2的表达和负自调节，但不直接参与调节达托霉素基因簇的表达。然而，达托霉素和A21978 C（1-3）的生产都需要BkdR。此外，bkdA 2B 2C 2的缺失仅导致A21978 C（1-3）产生的部分减少，而Delta bkdA 1B 1C 1突变体显示出非常弱的A21978 C（1-3）产生，并且双bkd突变体具有与单个Delta bkdA 1B 1C 1突变体相似的产生谱，这表明bkdA 1B 1C 1基因簇在支链脂肪酸生物合成中起主导作用。因此，我们揭示了BkdR的独特调节功能，并对bkd无效菌株进行了基因工程改造，以减少杂质用于达托霉素生产。
Daptomycin is a cyclic lipopeptide antibiotic produced by Streptomyces roseosporus in an acidic peptide complex A21978C. In this complex, A21978C(1-3) is most abundant and contains branched-chain fatty acyl groups, while daptomycin has a straight decanoic acyl group. The branched-chain alpha-keto acid dehydrogenase complex (BCDH complex), encoded by bkd gene clusters in Streptomyces, is responsible for the early step of converting branched-chain amino acids into branched-chain fatty acids. In a daptomycin industrial producer S. roseosporus L30, two alleles of bkd gene clusters, bkdA1B1C1/bkdA2B2C2, and a regulatory gene bkdR located upstream of bkdA2B2C2 are identified. We show that BkdR positively regulated bkdA2B2C2 expression and was negatively auto-regulated, but is not directly involved in regulation of daptomycin gene cluster expression. However, BkdR is required for both daptomycin and A21978C(1-3) production. Furthermore, deletion of bkdA2B2C2 only led to partial reduction of A21978C(1-3) production, while the Delta bkdA1B1C1 mutant shows very weak production of A21978C(1-3), and the double bkd mutant has a similar production profile as the single Delta bkdA1B1C1 mutant, suggesting that bkdA1B1C1 gene cluster plays a dominant role in branched-chain fatty acid biosynthesis. So we reveal a unique regulatory function of BkdR and genetic engineered a bkd null strain for daptomycin production with reduced impurities.