Reciprocal Regulation between SigK and Differentiation Programs in Streptomyces coelicolor
Reciprocal Regulation between SigK and Differentiation Programs in Streptomyces coelicolor
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天蓝色链霉菌 SigK 和分化程序之间的相互调节
DOI：
10.1128/jb.00875-09
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发表时间：
2009-11-01
影响因子：
3.2
通讯作者：
Li, Yong-Quan
中科院分区：
文献类型：
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作者：
Mao, Xu-Ming;Zhou, Zhan;Li, Yong-Quan
我们报道了天蓝色链霉菌中sigma因子SigK（SCO 6520）的缺失导致了较早的营养菌丝体到气生菌丝体的转换以及chpE和chpH的表达高于野生型。SigK的丧失也导致抗生素、放线菌紫素和十一烷基灵菌红素的加速和增强的产生，以及actII-orf 4和redD的表达增加。这些结果表明SigK在形态转变和次生代谢中起负作用。此外，sigK启动子（sigKp）活性逐渐增强，sigK表达部分依赖于SigK，但这种依赖性在基质菌丝发育过程中逐渐减弱。同时，SigK和绿色荧光蛋白之间发生了两次潜在的非特异性切割，在组成型启动子ermEp* 下表达的SigK融合蛋白在气生菌丝出现时急剧减少并消失。如果在sigKp下表达，则3FLAG-SigK显示类似的动态模式，但不像在ermEp* 下表达的SigK那样急剧下降。这些数据表明，SigK的攀缘表达可能减少营养菌丝发育过程中SigK的迅速降解，以获得适当的形态建成时间，而SigK的消失则消除了气生菌丝出现的障碍。因此，我们提出SigK对发育事件具有抑制作用，并且这些抑制作用可能通过SigK降解而释放。
Here we reported that deletion of SigK (SCO6520), a sigma factor in Streptomyces coelicolor, caused an earlier switch from vegetative mycelia to aerial mycelia and higher expression of chpE and chpH than that in the wild type. Loss of SigK also resulted in accelerated and enhanced production of antibiotics, actinorhodin, and undecylprodigiosin and increased expression of actII-orf4 and redD. These results suggested that SigK had a negative role in morphological transition and secondary metabolism. Furthermore, the sigK promoter (sigKp) activity gradually increased and sigK expression was partially dependent on SigK, but this dependence decreased during the developmental course of substrate mycelia. Meanwhile, two potentially nonspecific cleavages occurred between SigK and green fluorescent protein, and the SigK fusion proteins expressed under the constitutive promoter ermEp* sharply decreased and disappeared when aerial mycelia emerged. If expressed under sigKp, 3FLAG-SigK showed similar dynamic patterns but did not decrease as sharply as SigK expressed under ermEp*. These data suggested that the climbing expression of sigK might reduce the prompt degradation of SigK during vegetative hypha development for the proper timing of morphogenesis and that SigK vanished to remove the block for the emergence of aerial mycelia. Thus, we proposed that SigK had inhibitory roles on developmental events and that these inhibitory effects may be released by SigK degradation.