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 mainly governed by the plasmid copy number and promoter strength. g_csgA + RNA_pol → g_csgA + RNA_pol + mRNA_csgA $$g_{csgA}$$ $\alpha$ \[(Arab:AraC)\overset{K}{\rightarrow}mRNA\overset{\alpha}{\rightarrow}P\]

2.2 Translation

3 Translocation

3.1 Periplasmic export

3.2 Extracellular secretion