Research Paper

A single point mutation in the listerial betL σA-dependent promoter leads to improved osmo- and chill-tolerance and a morphological shift at elevated osmolarity

Volume 4, Issue 6   November/December 2013
http://dx.doi.org/10.4161/bioe.24094
Keywords: listeria, chill-tolerance, osmotolerance, salt stress, twisted cells
Authors: Roland F. Hoffmann, Susan McLernon, Audrey Feeney, Colin Hill and Roy D. Sleator

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Abstract:
Betaine uptake in Listeria monocytogenes is mediated by three independent transport systems, the simplest of which in genetic terms is the secondary transporter BetL. Using a random mutagenesis approach, based on the E. coli XL1 Red mutator strain, we identified a single point mutation in a putative promoter region upstream of the BetL coding region which leads to a significant increase in betL transcript levels under osmo- and chill-stress conditions and a concomitant increase in stress tolerance. Furthermore, the mutation appears to counter the heretofore unreported “twisted” cell morphology observed for L. monocytogenes grown at elevated osmolarities in tryptone soy broth.

Received: January 11, 2013; Accepted: February 24, 2013; Published Online: March 11, 2013

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