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B6db references: 27318028

type Journal Article
authors Schulz A, Stöveken N, Binzen IM, Hoffmann T, Heider J, Bremer E
title Feeding on compatible solutes: A substrate-induced pathway for uptake and catabolism of ectoines and its genetic control by EnuR
journal Environ Microbiol
Activity mocr
Family mocr
sel selected
ui 27318028
year (2017)
volume 19
number 3
pages 926-946
keywords doi: 10.1111/1462-2920.13414
abstract Ectoine and 5-hydroxyectoine are widely synthesized microbial osmostress protectants. They are also versatile nutrients but their catabolism and the genetic regulation of the corresponding genes are incompletely understood. Using the marine bacterium Ruegeria pomeroyi DSS-3, we investigated the utilization of ectoines and propose a seven steps comprising catabolic route that entails an initial conversion of 5-hydroxyectoine to ectoine, the opening of the ectoine ring, and the subsequent degradation of this intermediate to l-aspartate. The catabolic genes are co-transcribed with three genes encoding a 5-hydroxyectoine/ectoine-specific TRAP transporter. A chromosomal deletion of this entire gene cluster abolishes the utilization of ectoines as carbon and nitrogen sources. The presence of ectoines in the growth medium triggers enhanced expression of the importer and catabolic operon, a process dependent on a substrate-inducible promoter that precedes this gene cluster. EnuR, a member of the MocR/GabR-type transcriptional regulators, controls the activity of this promoter and functions as a repressor. EnuR contains a covalently bound pyridoxal-5'-phosphate, and we suggest that this co-factor is critical for the substrate-mediated induction of the 5-hydroxyectoine/ectoine import and catabolic genes. Bioinformatics showed that ectoine consumers are restricted to the Proteobacteria and that EnuR is likely a central regulator for most ectoine/5-hydroxyectoine catabolic genes.
last changed 2017/10/26 14:29

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