title: Zinc-Induced Transposition of Insertion Sequence Elements Contributes to Increased Adaptability of Cupriavidus metallidurans.
abstract: Bacteria can respond to adverse environments by increasing their genomic variability and subsequently facilitating adaptive evolution. To demonstrate this, the contribution of Insertion Sequence (IS) elements to the genetic adaptation of Cupriavidus metallidurans AE126 to toxic zinc concentrations was determined. This derivative of type strain CH34, devoid of its main zinc resistance determinant, is still able to increase its zinc resistance level. Specifically, upon plating on medium supplemented with a toxic zinc concentration, resistant variants arose in which a compromised cnrYX regulatory locus caused derepression of CnrH sigma factor activity and concomitant induction of the corresponding RND-driven cnrCBA efflux system. Late-occurring zinc resistant variants likely arose in response to the selective conditions, as they were enriched in cnrYX disruptions caused by specific IS elements whose transposase expression was found to be zinc-responsive. Interestingly, deletion of cnrH, and consequently the CnrH-dependent adaptation potential, still enabled adaptation by transposition of IS elements (ISRme5 and IS1086) that provided outward-directed promoters driving cnrCBAT transcription. Finally, adaptation to zinc by IS reshuffling can also enhance the adaptation to subsequent environmental challenges. Thus, transposition of IS elements can be induced by stress conditions and play a multifaceted, pivotal role in the adaptation to these and subsequent stress conditions.
authors.affiliation: Unit of Microbiology, Belgian Nuclear Research Centre (SCK•CEN)Mol, Belgium; Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre, Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, Katholieke Universiteit LeuvenLeuven, Belgium.
authors.forename: Joachim
authors.initials: J
authors.lastname: Vandecraen
authors.affiliation: Unit of Microbiology, Belgian Nuclear Research Centre (SCK•CEN) Mol, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: Monsieurs
authors.affiliation: Unit of Microbiology, Belgian Nuclear Research Centre (SCK•CEN) Mol, Belgium.
authors.forename: Max
authors.initials: M
authors.lastname: Mergeay
authors.affiliation: Unit of Microbiology, Belgian Nuclear Research Centre (SCK•CEN) Mol, Belgium.
authors.forename: Natalie
authors.initials: N
authors.lastname: Leys
authors.affiliation: Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre, Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven Leuven, Belgium.
authors.forename: Abram
authors.initials: A
authors.lastname: Aertsen
authors.affiliation: Unit of Microbiology, Belgian Nuclear Research Centre (SCK•CEN) Mol, Belgium.
authors.forename: Rob
authors.initials: R
authors.lastname: Van Houdt
keywords: Cupriavidus; adaptation; insertion sequence element; metal ions; resistance