Cyclic Di-GMP Phosphodiesterases RmdA and RmdB Are Involved in Regulating Colony Morphology and Development in Streptomyces coelicolor
Cyclic Di-GMP Phosphodiesterases RmdA and RmdB Are Involved in Regulating Colony Morphology and Development in Streptomyces coelicolor
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DOI：
10.1128/jb.00157-12
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发表时间：
2012-09-01
影响因子：
3.2
通讯作者：
Bennett, Jennifer A.
中科院分区：
文献类型：
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作者：
Hull, Travis D.;Ryu, Min-Hyung;Bennett, Jennifer A.
环二聚GMP（c-di-GMP）调节革兰氏阴性菌中的许多过程，但对其在革兰氏阳性菌中的作用知之甚少。在这里，我们表征两个C-二GMP磷酸二酯酶的丝状高GC革兰氏阳性放线菌天蓝色链霉菌，参与控制菌落形态和发展。两个磷酸二酯酶基因之一SCO 0928中的转座子突变，在此指定为rmdA（形态和发育调节因子A），导致孢子特异性灰色色素水平降低和孢子形成延迟。RmdA蛋白含有串联排列的GGDEF-EAL结构域，并具有c-di-GMP磷酸二酯酶活性，这从使用纯化蛋白的体外酶促测定中显而易见。RmdA含有PAS 9结构域并且是血红素蛋白。另一个GGDEF-EAL编码基因SCO 5495（命名为rmdB）的失活导致与rmdA突变体相同的表型。纯化的无跨膜结构域的RmdB可溶性片段也具有c-di-GMP磷酸二酯酶活性。的rmdA rmdB双突变体有一个秃头的表型，并在气生菌丝体形成受损。这表明RmdA和RmdB函数是相加的并且至少部分重叠。rmdA和rmdB突变可能导致细胞内c-di-GMP的局部池增加，因为单突变体中的细胞内c-di-GMP水平与野生型没有显著差异，而在双rmdA rmdB突变体中，c-di-GMP水平比野生型高3倍。这项研究强调了c-di-GMP依赖的信号在放线菌菌落形态和发育中的重要性，并确定了两个控制这些过程的c-di-GMP磷酸二酯酶。
Cyclic dimeric GMP (c-di-GMP) regulates numerous processes in Gram-negative bacteria, yet little is known about its role in Gram-positive bacteria. Here we characterize two c-di-GMP phosphodiesterases from the filamentous high-GC Gram-positive actinobacterium Streptomyces coelicolor, involved in controlling colony morphology and development. A transposon mutation in one of the two phosphodiesterase genes, SCO0928, hereby designated rmdA (regulator of morphology and development A), resulted in decreased levels of spore-specific gray pigment and a delay in spore formation. The RmdA protein contains GGDEF-EAL domains arranged in tandem and possesses c-di-GMP phosphodiesterase activity, as is evident from in vitro enzymatic assays using the purified protein. RmdA contains a PAS9 domain and is a hemoprotein. Inactivation of another GGDEF-EAL-encoding gene, SCO5495, designated rmdB, resulted in a phenotype identical to that of the rmdA mutant. Purified soluble fragment of RmdB devoid of transmembrane domains also possesses c-di-GMP phosphodiesterase activity. The rmdA rmdB double mutant has a bald phenotype and is impaired in aerial mycelium formation. This suggests that RmdA and RmdB functions are additive and at least partially overlapping. The rmdA and rmdB mutations likely result in increased local pools of intracellular c-di-GMP, because intracellular c-di-GMP levels in the single mutants did not differ significantly from those of the wild type, whereas in the double rmdA rmdB mutant, c-di-GMP levels were 3-fold higher than those in the wild type. This study highlights the importance of c-di-GMP-dependent signaling in actinomycete colony morphology and development and identifies two c-di-GMP phosphodiesterases controlling these processes.