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The EAL domain protein YciR acts as a trigger enzyme in a c‐di‐GMP signalling cascade in E. coli biofilm control
Author(s) -
Lindenberg Sandra,
Klauck Gisela,
Pesavento Christina,
Klauck Eberhard,
Hengge Regine
Publication year - 2013
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/emboj.2013.120
Subject(s) - biology , biofilm , enzyme , signalling , microbiology and biotechnology , biochemistry , genetics , bacteria
C‐di‐GMP—which is produced by diguanylate cyclases (DGC) and degraded by specific phosphodiesterases (PDEs)—is a ubiquitous second messenger in bacterial biofilm formation. In Escherichia coli , several DGCs (YegE, YdaM) and PDEs (YhjH, YciR) and the MerR‐like transcription factor MlrA regulate the transcription of csgD , which encodes a biofilm regulator essential for producing amyloid curli fibres of the biofilm matrix. Here, we demonstrate that this system operates as a signalling cascade, in which c‐di‐GMP controlled by the DGC/PDE pair YegE/YhjH (module I) regulates the activity of the YdaM/YciR pair (module II). Via multiple direct interactions, the two module II proteins form a signalling complex with MlrA. YciR acts as a connector between modules I and II and functions as a trigger enzyme: its direct inhibition of the DGC YdaM is relieved when it binds and degrades c‐di‐GMP generated by module I. As a consequence, YdaM then generates c‐di‐GMP and—by direct and specific interaction—activates MlrA to stimulate csgD transcription. Trigger enzymes may represent a general principle in local c‐di‐GMP signalling.