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Humboldt-Universität zu Berlin - Mikrobiologie

Humboldt-Universität zu Berlin | Institut für Biologie | Mikrobiologie | Hengge group | Research | Small regulatory RNAs in the control of E. coli biofilm formation

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Abb.: Regine Hengge

 

Small regulatory RNAs in the control of E. coli biofilm formation

By by base-pairing with mRNAs, small regulatory RNAs (sRNA) can affect mRNA degradation as well as translation and thereby provide an additional layer of control besides transcriptional regulation. In the transcription factor cascade (RpoS-DgcM/MlrA-CsgD) that activates curli and cellulose production in E. coli biofilms, an entire series of sRNAs - ArcZ, DsrA, RprA, McaS, OmrA/OmrB, GcvB and RydC – can bind to the mRNAs of rpoS, dgcM and/or csgD and either activate (rpoS) or inhibit (dgcM, csgD) translation. Moreover, some of these sRNAs also control expression of the flagellar master regulator FlhDC and thereby contribute to inverse coordination of flagella and matrix production in biofilms.

While the action of these sRNAs can be readily detected when they are overproduced, knockout mutations usually produce hardly any effects when assayed in standard liquid planktonic cultures. However, the observation of altered macrocolony morphology of some of these mutants indicates that these sRNAs might be particularly relevant in the control of amounts and spatial distribution of curli fibres and cellulose in biofilms. This is reflected in the 5´-UTR and translational initiation region of csgD mRNA being a major hub for sRNA binding.

 

Questions currently addressed in our group include the following:

  • How do sRNAs contribute to the spatial control of expression of CsgD, curli fibres and cellulose in macrocolony biofilms?
  • Do sRNAs that bind to the mRNAs of dgcM and csgD contribute to bistable CsgD expression in zones of heterogeneous matrix production in macrocolony biofilms?

 

Mika, F., and R. Hengge (2014) Small RNAs in the control of RpoS, CsgD and biofilm functions in Escherichia coli. RNA Biol. 11: 494-507.

Mika, F., and R. Hengge (2013) Small regulatory RNAs in the control of motility and biofilm formation of Escherichia coli and Salmonella. Int. J. Mol. Sci. 14, 4560-4579.

Mika, F., S. Busse, A. Possling, J. Berkholz, N. Tschowri, N. Sommerfeldt, M. Pruteanu, and R. Hengge (2012) Targeting of csgD by the small regulatory RNA RprA links stationary phase, cell envelope stress and biofilm formation in Escherichia coli. Mol. Microbiol. 84, 51-65.

 

Abb.: Franziska Mika und Regine Hengge in RNA Biology, 2014