Difference between revisions of "Part:BBa K4197005"

Latest revision as of 18:37, 10 October 2022

Gal d 2 expression at the surface of E. coli cells sortable by FACS using mRFP1

Introduction

The mRFP1 fluorescent reporter has been added on the plasmid allowing to express the gene of hen’s egg Gal d 2 (K4197009) on the surface of E. coli. Expression of mRFP1 is driven by the ihfb800 promoter (see K41970012). This red fluorescence is destined to identify the allergen expressing cells by FACS.

Construction

The ihfb800-mRFP1 construction was amplified by PCR with the high-fidelity Phusion polymerase using BFP/RFP IF+BglII R site R (cgcgggatcgagatctatcacgaggcagaatttcagat) and BFP/RFP IF+BglII R site F (tagaggatcgagatctctgaaacagtgcaaagctaaccc) primers. The expected size of the amplicon is 1622 bp. The fragment was inserted on the linearized plasmid pET21b(+) with Gal d 2 (K4197009) by In-Fusion.

The resulting products were transformed into Stellar cells and transformants were selected. Colonies were screened by PCR using screening_insert_R (ccgaaacaagcgctcatgagc) and screening_insert_F (ggttatgctagttattgctcagc) primers. The expected sizes of amplicons was 3688 bp with RFP and 2096 bp without.

Figure 1: Verification of the insertion of RFP fragment in Gal d 2 with gel. The PCR screening was checked with 0.6% agarose electrophoresis gel and revealed with EtBr. A theoretical gel is presented with each gel and the NEB 1 kb DNA ladder is used for the experimental gels (note that a different ladder is presented on the theoretical gel). Colonies 9, 10 and 11present the correct size for Gal d 2.

Successful colonies were further tested by digestion with NotI which cut both in the plasmid and in the mRFP1 gene (Figure 2). Correct sizes were expected to be 1922 and 6791 bp for Gal d 2.

Figure 2: Digestion by NotI of Gal d 2 with mRFP1 insertion. The digestion product was checked with 0.6% agarose electrophoresis gel and revealed with EtBr. A theoretical gel is presented with each gel and the NEB 1 kb DNA ladder is used for the experimental gels (note that a different ladder is presented on the theoretical gel). colonies 7 and 13 present the correct size for Gal d 2.

Validation

This construction has not shown red fluorescence on the microscope. After sequencing, a mutation has been revealed on the mRFP1 sequence which does not allow us to continue further with this construction.

DAISY Project

1. DAISY (INSA-UPS 2022)

Sequence and Features