Difference between revisions of "Part:BBa K2278002"

Latest revision as of 14:21, 23 February 2018

Vibrio cholerae CAI-1 (quorum sensing inducer) generator

Sequence and Features

Introduction

This DNA biobrick was designed in order to produce CAI-1 of Vibrio cholerae in E. coli strain.

1- Biological background

The production of the Vibrio cholerae quorum sensing inducer (CAI-1) is under the control of the cqsA gene coding for the CqsA synthase. This enzyme catalyzes the production of C8-CAI-1, an analog of CAI-1 quorum sensing inducer from Vibrio cholerae. The CqsA catalyzes the following reaction :

Figure 1: CAI-1 simplified production mechanism. CqsA synthase catalyses the reaction between (S)-adenosylmethionine (SAM) and decanoyl-coenzyme A. Ea-CAI-1 is then converted to CAI-1 (Wei et al. 2011). (figure is adapted from Wei et al. 2011)

2- Usage in iGEM projects

The BBa_K2278002 cames from the sensing module of the Croc’n cholera project (team INSA-UPS-France 2017) It was designed to produce CAI-1 by an E. coli strain to simulate the presence of Vibrio cholerae in a water sample and so, to allow the validation of our Vibrio cholerae quorum sensing based detection system.

The part includes Vibrio cholerae cqsA synthase under the control of an IPTG inducible promoter. The CAI-1 producing system is inducible in order to avoid toxicity problems and high metabolic activity during cells growth.

Experiments

Molecular biology

The cqsA coding gene was placed in silico under the control of the plac promoter (BBa_R0040), a strong RBS (BBa_B0034) and a terminator (BBa_B1006). IDT performed the DNA synthesis and delivered the part as gBlock.  The construct was cloned by conventional ligation into pSB1C3 plasmid and then transformed into E. coli Dh5-alpha strain. Three transformants were obtained.

Figure 2: Analyses of pSB1C3-VcCqsA restriction map. Digested plasmids (EcoRI and Pst1) are electrophoresed through a 1% agarose gel. The desired fragment lengths are in brackets. After digestion, the 2029 bp fragment corresponds to the pSB1C3 vector while the 1318 bp fragment corresponds to the cqsA gene.

Perceptives:

Design Notes

Terminator : BBa_B1006* pressent for this construction a mutated substitution at the 35th pair (initial A->T) due to IDT complexity requirements for gBlocks synthesis. The effect of the mutation was not investigated.

This biobrick is very close to Part:BBa_K356001. We proposed an alternative design by inversing the RBS and promoter place in the initial design. The promoter is now before the RBS and we used an inducible promoter in order to avoid toxicity problems and high metabolism activity during cell growth.

Source

This enzyme cames from Vibrio cholerae DNA genomic sequence.

References

Ng W-L, Perez LJ, Wei Y, Kraml C, Semmelhack MF & Bassler BL (2011) Signal production and detection specificity in Vibrio CqsA/CqsS quorum-sensing systems: Vibrio quorum-sensing systems. Molecular Microbiology 79 1407–1417

Wei, Y., Perez, L., Ng, W., Semmelhack, M. and Bassler, B. (2011). Mechanism of Vibrio cholerae Autoinducer-1 Biosynthesis. ACS Chemical Biology, 6(4), pp.356-365.