Two intercellular signals required for fruiting body formation in Myxococcus xanthus act sequentially but non-hierarchically
Two intercellular signals required for fruiting body formation in Myxococcus xanthus act sequentially but non-hierarchically
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DOI：
10.1111/j.1365-2958.2012.08173.x
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发表时间：
2012-10-01
影响因子：
3.6
通讯作者：
Sogaard-Andersen, Lotte
中科院分区：
文献类型：
--
作者：
Konovalova, Anna;Wegener-Feldbruegge, Sigrun;Sogaard-Andersen, Lotte
黄色粘球菌中饥饿诱导的子实体形成取决于细胞间信号传导。 A信号在饥饿2小时后发挥作用，其合成取决于asg基因。 C 信号在饥饿 6 小时后发挥作用，由蛋白酶 PopC 对前体进行蛋白水解切割而产生。先前的基因表达研究表明 A 信号和 C 信号位于分层通路上。在这里，我们探讨了 A 信号和 C 信号之间的因果关系。 asgA和asgB突变体减少了popC表达、PopC积累和C信号积累。 popC 表达不依赖于 A 信号，而是依赖于 AsgA 和 AsgB 蛋白。两个突变体中popC表达的恢复挽救了PopC和C信号积累以及C信号传导以及两个突变体的发育缺陷，但没有恢复A信号传导。基于这些结果，我们认为 A 信号和 C 信号并不位于分层的、依赖的通路上。相反，A 信号和 C 信号按顺序起作用，并且没有因果关系，这表明它们通过共享的计时机制联系在一起，这确保了饥饿期间 A 信号和 C 信号分别早起和晚起。这种通路拓扑代表了一种涉及多个信号的细菌细胞间信号系统的新颖架构。
Starvation-induced fruiting body formation in Myxococcus xanthus depends on intercellular signalling. A-signal functions after 2 h of starvation and its synthesis depends on the asg genes. C-signal functions after 6 h of starvation and is generated by proteolytic cleavage of a precursor by the protease PopC. Previous gene expression studies suggested that the A- and C-signal lie on a hierarchical pathway. Here we explored the causal relationship between the A- and C-signal. The asgA and asgB mutants have reduced popC expression, PopC accumulation and C-signal accumulation. popC expression was shown not to depend on A-signal but on the AsgA and AsgB proteins. Restored popC expression in the two mutants rescued PopC and C-signal accumulation as well as C-signalling and the developmental defects of the two mutants without restoring A-signalling. Based on these results we suggest that A- and C-signal do not lie on a hierarchical, dependent pathway. Instead the A- and C-signal act sequentially and without a causal relationship suggesting that they are linked by a shared timing mechanism, which ensures the early and late onset of A-signalling and C-signalling, respectively, during starvation. This pathway topology represents a novel architecture for bacterial intercellular signalling systems involving more than one signal.