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Sci Signal. 2017 Apr 18;10(475). pii: eaal3011. doi: 10.1126/scisignal.aal3011.

Control of potassium homeostasis is an essential function of the second messenger cyclic di-AMP in Bacillus subtilis.

Author information

1
Department of General Microbiology, Georg-August-University Göttingen, 37077 Göttingen, Germany.
2
Research Core Unit Metabolomics, Hannover Medical School, 30625 Hannover, Germany.
3
Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, 35043 Marburg, Germany.
4
Department of Genomic and Applied Microbiology, Georg-August-University Göttingen, 37077 Göttingen, Germany.
5
Department of Plant Ecology and Ecosystems Research, Georg-August-University Göttingen, 37077 Göttingen, Germany.
6
LOEWE Center for Synthetic Microbiology, Philipps-University Marburg, 35043 Marburg, Germany.
7
Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University Göttingen, 37077 Göttingen, Germany.
8
Department of General Microbiology, Georg-August-University Göttingen, 37077 Göttingen, Germany. jstuelk@gwdg.de.

Abstract

The second messenger cyclic di-adenosine monophosphate (c-di-AMP) is essential in the Gram-positive model organism Bacillus subtilis and in related pathogenic bacteria. It controls the activity of the conserved ydaO riboswitch and of several proteins involved in potassium (K+) uptake. We found that the YdaO protein was conserved among several different bacteria and provide evidence that YdaO functions as a K+ transporter. Thus, we renamed the gene and protein KimA (K+ importer A). Reporter activity assays indicated that expression beyond the c-di-AMP-responsive riboswitch of the kimA upstream regulatory region occurred only in bacteria grown in medium containing low K+ concentrations. Furthermore, mass spectrometry analysis indicated that c-di-AMP accumulated in bacteria grown in the presence of high K+ concentrations but not in low concentrations. A bacterial strain lacking all genes encoding c-di-AMP-synthesizing enzymes was viable when grown in medium containing low K+ concentrations, but not at higher K+ concentrations unless it acquired suppressor mutations in the gene encoding the cation exporter NhaK. Thus, our results indicated that the control of potassium homeostasis is an essential function of c-di-AMP.

PMID:
28420751
DOI:
10.1126/scisignal.aal3011
[Indexed for MEDLINE]

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