Difference between revisions of "Part:BBa K4727000"

Revision as of 08:10, 29 September 2023

A. baumannii & K. pneumoniae standard backbone

This plasmid backbone was developed by Wang et al [1], it is provided of two ORIs: the first one a pMB1/pUC high copy number ORI for E. coli, the second one is capable o maintaining the plasmid both in Acinetobacter baumannii and Klebsiella pneumoniae

This backbone has been made standard RFC[10] compatible and provided with the RFC[10] prefix and suffix. Flanked by prefix and suffix is located part BBa_J23119 that has been demonstrated able to promote mRNA synthesis in K. pneumoniae and A. baumannii

The plasmid brings KanR as a selection marker

Usage and Biology

This part it thought to be used to express synthtic constructs in non model organisms as Acinetobacter baumannii and Klebsiella pneumoniae. It has been successfully used to express a reporter expression cassette in these two species, see image above. We conducted a fluorescence emission analysis employing the Thermofisher Scientific Varioskan Lux plate reader. This assessment focused on the emission of a reporter gene, specifically the red fluorescent protein (RFP) with excitation at 535nm and emission at 610nm. Results are reported below.

Acinetobacter baumannii

Our experimental setup involved four colonies of A. baumannii, each harboring the RFP reporter gene within a cassette integrated into our newly developed backbone. To establish a comparative benchmark, we contrasted these expression levels with those of a standard E. coli TOP10 strain expressing the RFP gene under the control of both the relatively weak promoter BBa_J23101 and the strong promoter BBa_R0040.

Among the selected colonies, namely 1.2A, 1.2B, 1.1A, and 2.2A, a trio comprising 1.2A, 1.2B, and 1.1A exhibited analogous rates of reporter gene expression. This expression level surpassed that driven by BBa_J23101 yet remained notably lower than the robust pTet promoter. Conversely, colony 2.2A distinctly displayed heightened expression. Upon subjecting the expression cassette to Sanger sequencing, we determined that the elevated fluorescence emission stems from a mutation within the RFP coding sequence. This mutation, rather than the promoter itself, leads to a significant enhancement in emission intensity due to an amino acid substitution.

Klebsiella pneumoniae

The experiment was carried out in a similar fashion as described above: two colonies of K. pneumoniae were electroporated, with part BBa_K4727000 expressing a gene reporter, namely RFP, under the regulation of BBa_J23119 promoter. In parallel, the same wild type bacteria was used as a reference, together with our golden standards: E. coli expressing RFP under the control of pTet and BBa_J23101.

Sequence and Features