Pathway Model

1 Overview

Curli is the main proteinaceous component of the extracellular matrix naturally produced by *E. coli*. Although the main structural component is the self-assembling csgA monomer, there are a number of other proteins involved in its production and export. The curli production pathway can be broken down into two main modules: gene expression and translocation. The first, gene expression, is comprised of transcription and translation. Translocation can be further broken down into periplasmic export and extracellular secretion.

2 Gene Expression

2.1 Transcription

The naturally occurring genes corresponding to curli are organized into csgBAC and csgDEFG operons. csgD is a regulatory protein, and thus is not applicable for the expression of foreign plasmids. Additionally, due to the additional protein domains fused to the csgA monomer, it is placed on a plasmid on its own (\(g_{csgA}\)). The remaining genes are placed on another plasmid (\(g_{csgCEFG}\)). The rate of transcription is primarily governed by the plasmid copy number and promoter strength. $$g_{csgA} + RNA_{pol} \overset{K_{1}}{\rightarrow} g_{csgA} + RNA_{pol} + mRNA_{csgA}$$ $$g_{csgCEFG} + RNA_{pol} \overset{K_{1}}{\rightarrow} g_{csgCEFG} + RNA_{pol} + mRNA_{csgCEFG}$$

2.2 Translation

3 Translocation

3.1 Periplasmic export

3.2 Extracellular secretion