Parker Ashley, Cureoglu Suanur, De Lay Nicholas, Majdalani Nadim, Gottesman Susan
Laboratory of Molecular Biology, National Cancer Institute, Bethesda, MD, 20892, USA.
Mol Microbiol. 2017 Jul;105(2):309-325. doi: 10.1111/mmi.13702. Epub 2017 May 18.
Small regulatory RNAs have major roles in many regulatory circuits in Escherichia coli and other bacteria, including the transition from planktonic to biofilm growth. We tested Hfq-dependent sRNAs in E. coli for their ability, when overproduced, to inhibit or stimulate biofilm formation, in two different growth media. We identify two mutually exclusive pathways for biofilm formation. In LB, PgaA, encoding an adhesion export protein, played a critical role; biofilm was independent of the general stress factor RpoS or CsgD, regulator of curli and other biofilm genes. The PgaA-dependent pathway was stimulated upon overproduction of DsrA, via negative regulation of H-NS, or of GadY, likely by titration of CsrA. In yeast extract casamino acids (YESCA) media, biofilm was dependent on RpoS and CsgD, but independent of PgaA; RpoS appears to indirectly negatively regulate the PgaA-dependent pathway in YESCA medium. Deletions of most sRNAs had very little effect on biofilm, although deletion of hfq, encoding an RNA chaperone, was defective in both LB and YESCA. Deletion of ArcZ, a small RNA activator of RpoS, decreased biofilm in YESCA; only a portion of this defect could be bypassed by overproduction of RpoS. Overall, sRNAs highlight different pathways to biofilm formation.
小调控RNA在大肠杆菌和其他细菌的许多调控回路中发挥着重要作用，包括从浮游生长到生物膜生长的转变。我们在两种不同的生长培养基中测试了大肠杆菌中依赖于Hfq的小RNA在过量表达时抑制或刺激生物膜形成的能力。我们确定了生物膜形成的两条相互排斥的途径。在LB培养基中，编码粘附输出蛋白的PgaA发挥了关键作用；生物膜的形成不依赖于一般应激因子RpoS或CsgD（卷曲菌毛及其他生物膜基因的调节因子）。过量表达DsrA时，通过对H-NS的负调控，或过量表达GadY时，可能通过滴定CsrA，刺激了依赖PgaA的途径。在酵母提取物酪蛋白氨基酸（YESCA）培养基中，生物膜的形成依赖于RpoS和CsgD，但不依赖于PgaA；在YESCA培养基中，RpoS似乎间接负调控依赖PgaA的途径。大多数小RNA的缺失对生物膜的影响很小，尽管编码RNA伴侣的hfq的缺失在LB和YESCA中均有缺陷。RpoS的小RNA激活剂ArcZ的缺失降低了YESCA中的生物膜；RpoS的过量表达只能部分绕过这种缺陷。总体而言，小RNA突出了生物膜形成的不同途径。
