Difference between revisions of "Part:BBa K4990002"

Revision as of 11:12, 22 August 2023

mFadA B-domain

What you need to know!

Many bacteria have long chain fiber-protein complexes on their surfaces, which are called pili or fimbriae. These pili are composed of individual pilus monomers that link together end-to-end in the extracellular environment, self-assembling into long chain fibers with high physical strength.

For Fusobacterium nucleatum, its pili are referred to as FadA (Fusobacterium adhesin A). The monomers that make up these pili come in two forms: ①pre-FadA, which serves as an anchoring structure, attaching the entire pilus to the bacterial inner membrane. ②mFadA (mature FadA), which can link head-to-tail and self-assemble into a long filament.

In our project, the aim is to achieve bacteria-bacteria targeting. To accomplish this, we intend to leverage the self-assembly property of mFadA. We have fused a bacterial pilus monomer onto a membrane protein of the engineered bacterium, which we call the "fishing rod protein" . The membrane protein acts as the fishing rod, the linker serves as the fishing line, and the bacterial pilus monomer functions as the bait. By utilizing surface display techniques to display the fishing rod protein, our engineered bacteria can essentially "fish" for target bacteria, enabling precise bacteria-bacteria targeting.

However, displaying the entire bacterial pilus monomer directly on the surface would lead to a range of issues, including steric hindrance, nonspecificity, and metabolic waste. Therefore, we truncated the mFadA to address these concerns.

What it is?

Below is the structure of the mFadA B-domain:

However, not the entire structure of mFadA is involved in self-assembly. Thus, we considered removing unnecessary domains. Upon closer examination of mFadA's structure, we divided it into two domains: Domain A and Domain B. Domain A comprises two anti-parallel α-helical structures, while Domain B consists of a single anti-parallel α-helix. We believe that Domain B is the most crucial. On a microscale, it possesses the function of binding with Domain A, and on a macroscale, it exhibits the capability to target Fn (Fusobacterium nucleatum).

Sequence and Features