Difference between revisions of "Team:Harvard BioDesign/Project"

Enter Type 1 fimbriae. Start by saying that interaction with the physical environment is a huge problem in nature and has been worked on for billions of years. Make clear that we’re inspired by nature and that we’re mimicking nature’s design. In biological systems Type 1 Pili typically manifest as organelles on the surface of pathogenic E. coli which are responsible for urinary tract infections in humans. The pili are translated from the “Fim” system of genes in the E. coli genome. Formation of individual pili consists of a “chaperone-usher” pathway whereupon a fimD “chaperone” protein binds to a subunit of the pili and “ushers” it through a membrane pore to bind it to the elongating pilus. Repeating fimA subunits form the base of a helical rod roughly 7 nm in length, which are attached to two adapter proteins (FimF and FimG) and finally the FimH adhesin at the end of the pilus. The role which the pili play in these infections follows from its structure. FimH contains a mannose-binding domain which binds to mannose-containing receptors in host cells in the urinary tract epithelial tissue, activating a phagocytic process within the cells, leading to bacterial invasion and replication in the host cells (Wolf et al., 2002).

In the Fim genetic circuit, the FimE and FimB recombinases play an especially significant role in regulating expression of the Fim system and the resulting pili production. Containing an invertible 314-bp element called the “Fim switch,” the system is only able to be transcribed by the promoter when this switch is in the “on” orientation. FimE and FimB are located upstream of the rest of the Fim operon subunits.