WblC- and tetracycline-dependent shifts in the composition of Streptomyces coelicolor ribosomal proteome

WblC, also known as WhiB7, is a widely conserved WhiB-like transcription factor in actinomycetes that activates transcription of many targets upon antibiotic challenge to bring about intrinsic resistance to a wide range of translation-targeting antibiotics. As we found that WblC controls many genes involved in translation and that WblC promotes translation rate upon antibiotic stress in the model actinomycetes Streptomyces coelicolor, we speculated that WblC might alter the protein composition of ribosome during antibiotic stress. To test this, we prepared 70S ribosome fraction from wild-type S. coelicolor cells untreated or treated with tetracycline and ΔwblC mutant treated with tetracycline, and then compared the protein compositions of each 70S samples by mass spectrometric quantification.

WblC（亦称WhiB7）是放线菌中广泛保守的WhiB类转录因子，可在抗生素胁迫下激活众多靶基因的转录，进而使菌体对多种靶向翻译的抗生素（translation-targeting antibiotics）产生固有耐药性。我们此前发现，WblC可调控大量与翻译相关的基因，且在模式放线菌天蓝色链霉菌（Streptomyces coelicolor）中，WblC能够在抗生素胁迫下提升翻译速率，据此我们推测WblC可能在抗生素胁迫过程中改变核糖体的蛋白质组成。为验证上述推测，我们分别从未经处理的野生型天蓝色链霉菌、经四环素处理的野生型天蓝色链霉菌，以及经四环素处理的ΔwblC突变株（ΔwblC mutant）中提取了70S核糖体组分（70S ribosome fraction），随后通过质谱定量（mass spectrometric quantification）技术对比各组70S样品的蛋白质组成。