Shu Dan, Chen Lei, Wang Weihua, Yu Zhenyu, Ren Cong, Zhang Weiwen, Yang Sheng, Lu Yinhua, Jiang Weihong
Laboratory of Molecular Microbiology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Rd, Shanghai, 200032, People's Republic of China.
Appl Microbiol Biotechnol. 2009 Jan;81(6):1149-60. doi: 10.1007/s00253-008-1738-1. Epub 2008 Oct 24.
Two-component system AfsQ1-Q2 of Streptomyces coelicolor was identified previously for its ability to stimulate actinorhodin (ACT) and undecylprodigiosin (RED) production in Streptomyces lividans. However, disruption of either afsQ1 or afsQ2 in S. coelicolor led to no detectable changes in secondary metabolite formation or morphogenesis. In this study, we reported that, when cultivated on defined minimal medium (MM) with glutamate as the sole nitrogen source, the afsQ mutant exhibited significantly decreased ACT, RED, and calcium-dependent antibiotic (CDA) production and rapid growth of aerial mycelium. In addition, we also found that deletion of sigQ, which is located upstream of afsQ1-Q2 and encodes a putative sigma factor, led to the precocious hyperproduction of these antibiotics and delayed formation of sporulating aerial mycelium in the same glutamate-based defined MM. Reverse-transcription polymerase chain reaction and egfp fusion analyses showed that the expression of sigQ was under control by afsQ. In addition, deletion of both afsQ-sigQ resulted in the phenotype identical to that of afsQ mutant. The results suggested that afsQ1-Q2 and sigQ worked together in the regulation of both antibiotic biosynthesis and morphological development, and sigQ might be responsible for antagonizing the function of AfsQ1-Q2 in S. coelicolor, however, in a medium-dependent manner. Moreover, the study showed that the medium-dependent regulation of antibiotic biosynthesis by AfsQ1-Q2-SigQ was through pathway-specific activator genes actII-ORF4, redD, and cdaR. The study provides new insights on regulation of antibiotic biosynthesis and morphological development in S. coelicolor.
天蓝色链霉菌的双组分系统AfsQ1-Q2先前已被鉴定，因其能够刺激淡紫灰链霉菌中放线紫红素（ACT）和十一烷基灵菌红素（RED）的产生。然而，天蓝色链霉菌中afsQ1或afsQ2的破坏并未导致次级代谢产物形成或形态发生的可检测变化。在本研究中，我们报道，当在以谷氨酸为唯一氮源的限定基本培养基（MM）上培养时，afsQ突变体的ACT、RED和钙依赖性抗生素（CDA）产量显著降低，气生菌丝体快速生长。此外，我们还发现，位于afsQ1-Q2上游且编码假定σ因子的sigQ缺失，导致这些抗生素早熟超量产生，并在相同的基于谷氨酸的限定MM中延迟形成产孢气生菌丝体。逆转录聚合酶链反应和egfp融合分析表明，sigQ的表达受afsQ控制。此外，afsQ-sigQ两者均缺失导致的表型与afsQ突变体相同。结果表明，afsQ1-Q2和sigQ在抗生素生物合成和形态发育的调控中共同起作用，并且sigQ可能负责拮抗天蓝色链霉菌中AfsQ1-Q2的功能，然而，是以培养基依赖性方式。此外，该研究表明，AfsQ1-Q2-SigQ对抗生素生物合成的培养基依赖性调控是通过途径特异性激活基因actII-ORF4、redD和cdaR进行的。该研究为天蓝色链霉菌中抗生素生物合成和形态发育的调控提供了新的见解。
