Please use this identifier to cite or link to this item:
https://hdl.handle.net/10216/127799
Author(s): | Rocha, R Teixeira-Duarte, CM JMP, J Morais-Cabral, JH |
Title: | Characterization of the molecular properties of KtrC, a second RCK domain that regulates a Ktr channel in Bacillus subtilis |
Publisher: | Academic Press |
Issue Date: | 2019 |
Abstract: | RCK (regulating conductance of K+) domains are common regulatory domains that control the activity of eukaryotic and prokaryotic K+ channels and transporters. In bacteria these domains play roles in osmoregulation, regulation of turgor and membrane potential and in pH homeostasis. Whole-genome sequencing unveiled RCK gene redundancy, however the biological role of this redundancy is not well understood. In Bacillus subtilis, there are two closely related RCK domain proteins (KtrA and KtrC) that regulate the activity of the Ktr cation channels. KtrA has been well characterized but little is known about KtrC. We have characterized the structural and biochemical proprieties of KtrC and conclude that KtrC binds ATP and ADP, just like KtrA. However, in solution KtrC exist in a dynamic equilibrium between octamers and non-octameric species that is dependent on the bound ligand, with ATP destabilizing the octameric ring relative to ADP. Accordingly, KtrC-ADP crystal structures reveal closed octameric rings similar to those in KtrA, while KtrC-ATP adopts an open assembly with RCK domains forming a super-helix. In addition, both KtrC-ATP and -ADP octamers are stabilized by the signaling molecule cyclic-di-AMP, which binds to KtrC with high affinity. In contrast, c-di-AMP binds with 100-fold lower affinity to KtrA. Despite these differences we show with an E. coli complementation assay that KtrC and KtrA are interchangeable and able to form functional transporters with both KtrB and KtrD. The distinctive properties of KtrC, in particular ligand-dependent assembly/disassembly, suggest that this protein has a specific physiological role that is distinct from KtrA. |
Subject: | Adenosine Diphosphate / chemistry Adenosine Diphosphate / metabolism Adenosine Triphosphate / chemistry Adenosine Triphosphate / metabolism Amino Acid Motifs Bacillus subtilis / chemistry Bacillus subtilis / metabolism Bacterial Proteins / chemistry Bacterial Proteins / genetics Bacterial Proteins / metabolism Binding Sites Cation Transport Proteins / chemistry Cation Transport Proteins / genetics Cation Transport Proteins / metabolism Cations, Monovalent Cloning, Molecular Crystallography, X-Ray Dinucleoside Phosphates / chemistry Dinucleoside Phosphates / metabolism Escherichia coli / genetics Escherichia coli / metabolism Gene Expression Genetic Complementation Test Genetic Vectors / chemistry Genetic Vectors / metabolism Ion Transport Models, Molecular Potassium / chemistry Potassium / metabolism Protein Binding Protein Conformation, alpha-Helical Protein Conformation, beta-Strand Protein Interaction Domains and Motifs Protein Isoforms / chemistry Protein Isoforms / genetics Protein Isoforms / metabolism Protein Multimerization Recombinant Proteins / chemistry Recombinant Proteins / genetics Recombinant Proteins / metabolism |
URI: | https://hdl.handle.net/10216/127799 |
Catalogue Link: | http://creativecommons.org/licenses/by-nc-nd/4.0/ |
Series: | Journal of structural biology, vol. 205(3) pag. 34-43 |
Document Type: | Artigo em Revista Científica Internacional |
Rights: | openAccess |
Appears in Collections: | I3S - Artigo em Revista Científica Internacional |
Files in This Item:
File | Description | Size | Format | |
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10.1016-j.jsb.2019.02.002.pdf | 1.53 MB | Adobe PDF | View/Open | |
SupplementalData.docx | 7.88 MB | Microsoft Word XML | View/Open |
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