Sommerfeldt Nicole, Possling Alexandra, Becker Gisela, Pesavento Christina, Tschowri Natalia, Hengge Regine
Institut für Biologie - Mikrobiologie, Freie Universität Berlin, 14195 Berlin, Germany.
Microbiology (Reading). 2009 Apr;155(Pt 4):1318-1331. doi: 10.1099/mic.0.024257-0.
Switching from the motile planktonic bacterial lifestyle to a biofilm existence is stimulated by the signalling molecule bis-(3'-5')-cyclic-diguanosine monophosphate (cyclic-di-GMP), which is antagonistically controlled by diguanylate cyclases (DGCs; characterized by GGDEF domains) and specific phosphodiesterases (PDEs; mostly featuring EAL domains). Here, we present the expression patterns of all 28 genes that encode GGDEF/EAL domain proteins in Escherichia coli K-12. Twenty-one genes are expressed in Luria-Bertani medium, with 15 being under sigma(S) control. While a small subset of GGDEF/EAL proteins (YeaJ and YhjH) is dominant and modulates motility in post-exponentially growing cells, a diverse battery of GGDEF/EAL proteins is deployed during entry into stationary phase, especially in cells grown at reduced temperature (28 degrees C). This suggests that multiple signal input into cyclic-di-GMP control is particularly important in growth-restricted cells in an extra-host environment. Six GGDEF/EAL genes differentially control the expression of adhesive curli fimbriae. Besides the previously described ydaM, yciR, yegE and yhjH genes, these are yhdA (csrD), which stimulates the expression of the DGC YdaM and the major curli regulator CsgD, and yeaP, which contributes to expression of the curli structural operon csgBAC. Finally, we discuss why other GGDEF/EAL domain-encoding genes, despite being expressed, do not influence motility and/or curli formation.
信号分子双（3'-5'）-环二鸟苷单磷酸（环二鸟苷酸）可刺激细菌从游动的浮游生活方式转变为生物膜存在形式，环二鸟苷酸受双鸟苷酸环化酶（DGCs；以GGDEF结构域为特征）和特定磷酸二酯酶（PDEs；大多具有EAL结构域）的拮抗控制。在此，我们展示了大肠杆菌K-12中编码GGDEF/EAL结构域蛋白的所有28个基因的表达模式。21个基因在Luria-Bertani培养基中表达，其中15个受σ（S）调控。虽然一小部分GGDEF/EAL蛋白（YeaJ和YhjH）占主导并调节指数生长期后细胞的运动性，但在进入稳定期时会部署多种GGDEF/EAL蛋白，尤其是在低温（28摄氏度）下生长的细胞中。这表明在宿主外环境中生长受限的细胞中，多个信号输入到环二鸟苷酸控制中尤为重要。六个GGDEF/EAL基因差异控制粘附性卷曲菌毛的表达。除了先前描述的ydaM、yciR、yegE和yhjH基因外，还有yhdA（csrD），它刺激DGC YdaM和主要卷曲菌毛调节因子CsgD的表达，以及yeaP，它有助于卷曲菌毛结构操纵子csgBAC的表达。最后，我们讨论了为什么其他编码GGDEF/EAL结构域的基因尽管表达了，但并不影响运动性和/或卷曲菌毛的形成。
