Open AccessEctoine functions as an osmoprotectant in Bacillus subtilis and is accumulated via the ABC‐transport system OpuC
Author(s) -
Jebbar Mohamed,
Blohn Carsten,
Bremer Erhard
Publication year - 1997
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1997.tb12663.x
Subject(s) - ectoine , osmoprotectant , betaine , bacillus subtilis , biochemistry , glycine , chemistry , biology , bacteria , proline , amino acid , genetics
We report here that the cyclic amino acid ectoine functions as an osmoprotectant for the soil bacterium Bacillus subtilis . Growth experiments with a set of B . subtilis strains that carry defined mutations in the glycine betaine transport systems OpuA, OpuC and OpuD and the choline transport system OpuB revealed that ectoine was specifically accumulated via the ABC‐transport system OpuC. Competition experiments employing unlabeled ectoine and radiolabeled glycine betaine showed that the OpuC transport system has a low affinity for ectoine with a K i value of approximately 1.5 mM. Ectoine was identified by 1 H NMR spectroscopy in the solute pool of cells grown in the presence of ectoine. Ectoine could not be used by B . subtilis as sole carbon or nitrogen source. Our data thus characterise ectoine as a metabolically inert stress compound for B . subtilis and establish a crucial role for the ABC‐transport system OpuC for the acquisition of the osmoprotectant ectoine from the environment.