诱导对卷曲霉素的抗性活化变铅青链霉菌和天蓝色链霉菌的抗生素生产

摘要

目的:建立抗生素菌株选育的新方法.方法:变铅青链霉菌和天蓝色链霉菌A3(2)的relA突变株的合成微量放线紫红素(Act)和十一烷基灵菌红素(Red),通过诱导对卷曲霉素的抗性,筛选能够恢复或活化Act和Red合成的突变株,并应用蛋白质印迹分析考察活化或恢复Act或Red的合成与表达两个抗生素生物合成途径中的调节蛋白ActII-ORF4或RedD之间关系.结果:一些卷曲霉素抗性突变株(cap)的突变能够恢复relA突变株被损伤的抗生素合成和活化变铅青链霉菌的抗生素(Act和Red)合成,但没有恢复ppGpp合成,暗示着cap突变能够使天蓝色链霉菌不依赖ppGpp分子启动抗生素的合成;变铅青链霉菌66的cap突变株展现不同的表型,其基因突变的位点或类型可能互不相同.结论:建立了一个新的抗生素生产菌株选育方法,即诱导生产菌株对卷曲霉素的抗性.%AIM:To develop a novel method for improving antibiotic-producing strains. METHODS: The actinorhodin (Act) and undecylprodigosin (Red) biosyntheses in Streptomyces lividans 66 and a relA mutant of Streptomyces coelicolor A3(2) were impaired. The mutants with activated/restored Act and Red production were selected by inducing resistance to capreomycin, a basic peptide antibiotic. Western blotitng analysis was made to investigate the relationship between activated Act and Red production and the expression of ActII-ORF4 and RedD, the Act and RedD biosynthetic pathway-specific regulators, respectively. RESULTS: the capreomycin-resistant (cap) mutations could restore the impaired antibiotic production in Streptomyces coelicolor RelA (relA) without recovering the ppGpp synthesis, and activate the Act and Red production in Streptomyces lividans 66, suggesting that the dependence of Streptomyces coelicolor on ppGpp to initiate antibiotic biosynthesis could be bypassed by cap mutations. These cap mutants of Streptomyces lividans 66 exhibited different phenotypes with several different mutational types possibly appearing in them, although we have not found the mutational positions so far. CONCLUSION: Our observations demonstrated that cap mutations could activate Act and Red biosyntheses through directly or indirectly upregulating the expression of proteins ActII-ORF4 and RedD, respectively. One novel method to improve antibiotic-producing strains has been found.