CsgD is a
transcription
Transcription refers to the process of converting sounds (voice, music etc.) into letters or musical notes, or producing a copy of something in another medium, including:
Genetics
* Transcription (biology), the copying of DNA into RNA, the fir ...
and
response regulator protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
referenced to as the master modulator of bacterial
biofilm
A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular ...
development. In ''
E. coli
''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escher ...
'' cells, CsgD is tasked with aiding the transition from planktonic cell motility to the stationary phase of biofilm formation, in response to environmental growth factors.
A transcription analysis assay (happening ''in vitro'') illustrated a heightened decrease in CsgD's DNA-binding capacity when phosphorylated at
A.A. D59 of the protein's
primary sequence
Biomolecular structure is the intricate folded, three-dimensional shape that is formed by a molecule of protein, DNA, or RNA, and that is important to its function. The structure of these molecules may be considered at any of several length sc ...
.
Therefore, in the protein's active form (unphosphorylated), CsgD is capable of carrying out its normal functions of regulating
curli proteins (
fimbria) and producing
ECM
ECM may refer to:
Economics and commerce
* Engineering change management
* Equity capital markets
* Error correction model, an econometric model
* European Common Market
Mathematics
* Elliptic curve method
* European Congress of Mathematics
...
polysaccharides (
cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...
).
Following a promoter-''lacZ'' fusion assay of ''CsgD binding'' to specific target sites on E. coli's genome, two classes of binding targets were identified: ''group I genes'' and ''group II genes''.
The group I genes, akin to ''fliE'' and ''yhbT'', exhibit repressed transcription following their interaction with CsgD, whilst ''group II genes'', including ''yccT'' and ''adrA'', illustrated active functionality.
Other group I
operons that illustrate repressed transcription include ''fliE'' and ''fliEFGH,'' for motile flagellum formation.
Other group II genes, imperative to the transition towards stationary biofilm development, include ''csgBA'', encoding for curli fimbriae, and ''adrA'', encoding for the synthesis of
cyclic diguanylate.
In this context, c-di-GMP functions as a bacterial secondary messenger, enhancing the production of extracellular cellulose and impeding flagellum production and rotation.
References
{{reflist
Bacterial proteins