The conformations of the manganese transport regulator of Bacillus subtilis in its metal-free state
| Autor: | Richard G. Brennan, John D. Helmann, David L. Farrens, Arthur Glasfeld, Joseph I. Kliegman, Mark A. DeWitt |
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| Rok vydání: | 2006 |
| Předmět: |
DNA
Bacterial Dimer Protein subunit Allosteric regulation Mutant chemistry.chemical_element Bacillus subtilis Manganese Crystallography X-Ray Protein Structure Secondary Article chemistry.chemical_compound Bacterial Proteins Structural Biology Molecular Biology biology Biological Transport Site-directed spin labeling biology.organism_classification Protein tertiary structure Crystallography Protein Subunits chemistry Molecular Probes Spin Labels Apoproteins |
| Zdroj: | Journal of molecular biology. 365(5) |
| ISSN: | 0022-2836 |
| Popis: | The manganese transport regulator (MntR) from Bacillus subtilis binds cognate DNA sequences in response to elevated manganese concentrations. MntR functions as a homodimer that binds two manganese ions per subunit. Metal binding takes place at the interface of the two domains that comprise each MntR subunit: an N-terminal DNA-binding domain and a C-terminal dimerization domain. In order to elucidate the link between metal binding and activation, a crystallographic study of MntR in its metal-free state has been undertaken. Here we describe the structures of the native protein and a selenomethionine-containing variant, solved to 2.8 A. The two structures contain five crystallographically unique subunits of MntR, providing diverse views of the metal-free protein. In apo-MntR, as in the manganese complex, the dimer is formed by dyad-related C-terminal domains that provide a conserved structural core. Similarly, each DNA-binding domain largely retains the folded conformation found in metal bound forms of MntR. However, compared to metal-activated MntR, the DNA-binding domains move substantially with respect to the dimer interface in apo-MntR. Overlays of multiple apo-MntR structures indicate that there is a greater range of positioning allowed between N and C-terminal domains in the metal-free state and that the DNA-binding domains of the dimer are farther apart than in the activated complex. To further investigate the conformation of the DNA-binding domain of apo-MntR, a site-directed spin labeling experiment was performed on a mutant of MntR containing cysteine at residue 6. Consistent with the crystallographic results, EPR spectra of the spin-labeled mutant indicate that tertiary structure is conserved in the presence or absence of bound metals, though slightly greater flexibility is present in inactive forms of MntR. |
| Databáze: | OpenAIRE |
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