Bacteria inhabiting a biofilm are protected from physical stress, antimicrobials, and the host immune system, and thereby cause severe medical, environmental, and technical problems. Biofilm formation in Escherichia coli is regulated by two inversely controlled transcriptional feedforward cascades, the FlhDC/FliA cascade and the sigmaS/MlrA/CsgD cascade, which are active in post-exponentially growing and in stationary phase cells, respectively. Their final outputs, flagella production or the synthesis of the biofilm matrix components curli and cellulose, are mutually exclusive due to complementary sigma factor requirements, the abundant DNA-binding regulator FliZ, and opposite regulation by c-di-GMP. The RNA-binding protein CsrA, a central component of the global regulatory system, inhibits synthesis of the poly-N-acetyl-glucosamine (PGA) exopolysaccharide and glycogen and stimulates the expression of the flagellar master regulator FlhDC. CsrA activity is counteracted by two sRNAs, CsrB and CsrC. The lower figure shows that FlhDC, sigmaS, and CsgD, the transcription factors that control large regulons involved in flagellar and biofilm formation, serve as regulatory hubs for multiple environmental signal integration with a series of sRNAs providing distinct inputs.

Cellular Processes; Cellular community - prokaryotes
BRITE hierarchy

PMID:25028968

Mika F, Hengge R

Small RNAs in the control of RpoS, CsgD, and biofilm architecture of Escherichia coli.

RNA Biol 11:494-507 (2014)
DOI:10.4161/rna.28867

PMID:23443158

Mika F, Hengge R

Small Regulatory RNAs in the Control of Motility and Biofilm Formation in E. coli and Salmonella.

Int J Mol Sci 14:4560-79 (2013)
DOI:10.3390/ijms14034560

PMID:19287449

Hengge R

Principles of c-di-GMP signalling in bacteria.

Nat Rev Microbiol 7:263-73 (2009)
DOI:10.1038/nrmicro2109

PMID:23178000

Chambers JR, Sauer K

Small RNAs and their role in biofilm formation.

Trends Microbiol 21:39-49 (2013)
DOI:10.1016/j.tim.2012.10.008

PMID:24724055

Martinez LC, Vadyvaloo V

Mechanisms of post-transcriptional gene regulation in bacterial biofilms.

Front Cell Infect Microbiol 4:38 (2014)
DOI:10.3389/fcimb.2014.00038

PMID:23023210

Kalia D, Merey G, Nakayama S, Zheng Y, Zhou J, Luo Y, Guo M, Roembke BT, Sintim HO

Nucleotide, c-di-GMP, c-di-AMP, cGMP, cAMP, (p)ppGpp signaling in bacteria and implications in pathogenesis.

Chem Soc Rev 42:305-41 (2013)
DOI:10.1039/c2cs35206k

PMID:24217225

Seyll E, Van Melderen L

The ribonucleoprotein Csr network.

Int J Mol Sci 14:22117-31 (2013)
DOI:10.3390/ijms141122117

PMID:18765794

Pesavento C, Becker G, Sommerfeldt N, Possling A, Tschowri N, Mehlis A, Hengge R

Inverse regulatory coordination of motility and curli-mediated adhesion in Escherichia coli.

Genes Dev 22:2434-46 (2008)
DOI:10.1101/gad.475808

PMID:16427772

Huang YH, Ferrieres L, Clarke DJ

The role of the Rcs phosphorelay in Enterobacteriaceae.

Res Microbiol 157:206-12 (2006)
DOI:10.1016/j.resmic.2005.11.005

PMID:17557827

Li J, Attila C, Wang L, Wood TK, Valdes JJ, Bentley WE

Quorum sensing in Escherichia coli is signaled by AI-2/LsrR: effects on small RNA and biofilm architecture.

J Bacteriol 189:6011-20 (2007)
DOI:10.1128/JB.00014-07