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Compensating for over-production inhibition of the Hsmar1 transposon in Escherichia coli using a series of constitutive promoters

Tellier, Michael; Chalmers, Ronald


Michael Tellier

Professor of Biochemistry and Cell Biology


© 2020 The Author(s). Background: Transposable elements (TEs) are a diverse group of self-mobilizing DNA elements. Transposition has been exploited as a powerful tool for molecular biology and genomics. However, transposition is sometimes limited because of auto-regulatory mechanisms that presumably allow them to cohabit within their hosts without causing excessive genomic damage. The papillation assay provides a powerful visual screen for hyperactive transposases. Transposition is revealed by the activation of a promoter-less lacZ gene when the transposon integrates into a non-essential gene on the host chromosome. Transposition events are detected as small blue speckles, or papillae, on the white background of the main Escherichia coli colony. Results: We analysed the parameters of the papillation assay including the strength of the transposase transcriptional and translational signals. To overcome certain limitations of inducible promoters, we constructed a set of vectors based on constitutive promoters of different strengths to widen the range of transposase expression. We characterized and validated our expression vectors with Hsmar1, a member of the mariner transposon family. The highest rate of transposition was observed with the weakest promoters. We then took advantage of our approach to investigate how the level of transposition responds to selected point mutations and the effect of joining the transposase monomers into a single-chain dimer. Conclusions: We generated a set of vectors to provide a wide range of transposase expression which will be useful for screening libraries of transposase mutants. The use of weak promoters should allow screening for truly hyperactive transposases rather than those that are simply resistant to auto-regulatory mechanisms, such as overproduction inhibition (OPI). We also found that mutations in the Hsmar1 dimer interface provide resistance to OPI in bacteria, which could be valuable for improving bacterial transposon mutagenesis techniques.


Tellier, M., & Chalmers, R. (2020). Compensating for over-production inhibition of the Hsmar1 transposon in Escherichia coli using a series of constitutive promoters. Mobile DNA, 11(1),

Journal Article Type Article
Acceptance Date Jan 1, 2020
Online Publication Date Jan 10, 2020
Publication Date Jan 10, 2020
Deposit Date Jan 15, 2020
Journal Mobile DNA
Print ISSN 1759-8753
Electronic ISSN 1759-8753
Publisher Springer Verlag
Peer Reviewed Peer Reviewed
Volume 11
Issue 1
Article Number 5
Keywords Molecular Biology
Public URL
Publisher URL


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