Project Details
Projekt
Molecular basis for the control of K(+) uptake via KtrAB and KimA by cyclic di-AMP
Applicants
Professorin Dr. Inga Hänelt; Dr. Janet Vonck
Subject Area
Structural Biology
Biophysics
Metabolism, Biochemistry and Genetics of Microorganisms
Biophysics
Metabolism, Biochemistry and Genetics of Microorganisms
Term
from 2019 to 2023
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 423650202
The potassium homeostasis is essential for bacterial survival and controlled by the orchestrated function of various K(+) importers and exporters. While different ligands and stimuli have been thought to regulate those, recently, cyclic di-AMP has been identified as overarching regulatory signaling molecule in different Gram-positive bacteria. The production of cyclic di-AMP appears to depend on the K(+) (availability. At an excess of external potassium an increased intracellular cyclic di-AMP level was detected. Vice versa, the uptake and release of potassium was shown to be modulated both by the control of gene expression and protein activity by cyclic di-AMP. In Bacillus subtilis cyclic di-AMP directly binds to K(+) importers KtrAB and KimA leading to their inhibition. However, the underlying mechanism of protein deactivation remains elusive. Here, we will shed light on the molecular principles of cyclic di-AMP binding and transport inhibition. Since K(+) channel KtrAB and potassium-proton symporter KimA supposedly do not share any structural similarities, different binding motifs and regulatory mechanisms are expected. The binding sites and structural consequences of cyclic di-AMP binding will be solved by single particle cryo-electron microscopy and X-ray crystallography. Pulsed EPR spectroscopy will elucidate the nucleotide-dependent conformational dynamics of KtrAB and KimA. Complementary mutational studies in combination with functional assays will identify residues required for nucleotide binding and the subsequent regulation of activity.
DFG Programme
Priority Programmes
