Difference between revisions of "Part:BBa K2203003"

Latest revision as of 02:30, 2 November 2017

HepHCV_ToeholdA

This composite part consists of a T7 promoter (BBa_J64997) in front of the toehold, lacZalpha (BBa_I732006) downstream and a T7 terminator (BBa_K731721) at the end. A toehold switch works according to this scheme: when the trigger sequence in form of RNA or ssDNA is present in the sample, the toehold will unfold and lacZalpha will be translated. For more information about toeholds, go to 2017.igem.org/Team:EPFL . The equence of this toehold is detecting a part of the Hepatitic C virus. This part can now be used in combination with cell-free extracts to detect the presence of Hepatitis C virus in a sample.

The reporter system in our toeholds(K2203004, K2203005 for zika detection and K2203003, K2203006 for hepatitis C detection) works as follows:

- M15 cells have a lacZ delta mutation which makes them encode a form of beta-galactosidase lacking residues 11-41.

- Beta-galactosidase produced without those residues is missing a small part and is thus not functional.

- Upon the annealing of a trigger zika sequence to the toehold switch, the toehold unfolds and the lacZalpha coding sequence is translated.

- The production of the lacZaplpha part and the indigenous presence of the lacZ omega part in M15 cells allows for alpha complementation and production of a functional beta-galactosidase that can be detected by the addition of a colorimetric substrate CPRG Chlorophenol red-β-D-galactopyranoside.

Characterization of the HepC_Toehold_A in T7M15 lysate in the presence of a single stranded DNA trigger

Expression of LacZalpha was measured on a plate reader. Toehold and trigger were added to a usual lysate reaction as described here. Reactants were kept at 37°C for five hours.

The toehold is successfully triggered and LacZalpha translated.

Sequence and Features