2F5F: Bacillus Subtilis Manganese Transport Regulator (Mntr) Bound To Manganese, Ac Conformation, Ph 8.5

Citation:
Abstract
The manganese transport regulator (MntR) of Bacillus subtilis is activated by Mn(2+) to repress transcription of genes encoding transporters involved in the uptake of manganese. MntR is also strongly activated by cadmium, both in vivo and in vitro, but it is poorly activated by other metal cations, including calcium and zinc. The previously published MntR.Mn(2+) structure revealed a binuclear complex of manganese ions with a metal-metal separation of 3.3 A (herein designated the AB conformer). Analysis of four additional crystal forms of MntR.Mn(2+) reveals that the AB conformer is only observed in monoclinic crystals at 100 K, suggesting that this conformation may be stabilized by crystal packing forces. In contrast, monoclinic crystals analyzed at room temperature (at either pH 6.5 or pH 8.5), and a second hexagonal crystal form (analyzed at 100 K), all reveal the shift of one manganese ion by 2.5 A, thereby leading to a newly identified conformation (the AC conformer) with an internuclear distance of 4.4 A. Significantly, the cadmium and calcium complexes of MntR also contain binuclear complexes with a 4.4 A internuclear separation. In contrast, the zinc complex of MntR contains only one metal ion per subunit, in the A site. Isothermal titration calorimetry confirms the stoichiometry of Mn(2+), Cd(2+), and Zn(2+) binding to MntR. We propose that the specificity of MntR activation is tied to productive binding of metal ions at two sites; the A site appears to act as a selectivity filter, determining whether the B or C site will be occupied and thereby fully activate MntR.
PDB ID: 2F5FDownload
MMDB ID: 38226
PDB Deposition Date: 2005/11/25
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 2.4  Å
Source Organism:
Similar Structures:
Biological Unit for 2F5F: dimeric; determined by author and by software (PISA)
Molecular Components in 2F5F
Label Count Molecule
Proteins (2 molecules)
2
Transcriptional Regulator Mntr(Gene symbol: mntR)
Molecule annotation
Chemicals (4 molecules)
1
4
* Click molecule labels to explore molecular sequence information.

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