Dataset Information

Arginine 116 stabilizes the entrance to the metal ion-binding site of the MntC protein.

ABSTRACT: The cyanobacterium Synechocystis sp. PCC 6803 imports Mn2+ ions via MntCAB, an ABC transport system that is expressed at submicromolar Mn2+ concentrations. The structures of the wild type (WT) and a site-directed mutant of the MntC solute-binding protein have been determined at 2.7 and 3.5?Å resolution, respectively. The WT structure is significantly improved over the previously determined structure (PDB entry 1xvl), showing improved Mn2+ binding site parameters, disulfide bonds in all three monomers and ions bound to the protein surface, revealing the role of Zn2+ ions in the crystallization liquor. The structure of MntC reveals that the active site is surrounded by neutral-to-positive electrostatic potential and is dominated by a network of polar interactions centred around Arg116. The mutation of this residue to alanine was shown to destabilize loops in the entrance to the metal-ion binding site and suggests a possible role in MntC function.

SUBMITTER: Kanteev M

PROVIDER: S-EPMC3606565 | biostudies-literature | 2013 Mar

REPOSITORIES: biostudies-literature

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Arginine 116 stabilizes the entrance to the metal ion-binding site of the MntC protein.

Kanteev Margarita M Adir Noam N

Acta crystallographica. Section F, Structural biology and crystallization communications 20130222 Pt 3

The cyanobacterium Synechocystis sp. PCC 6803 imports Mn2+ ions via MntCAB, an ABC transport system that is expressed at submicromolar Mn2+ concentrations. The structures of the wild type (WT) and a site-directed mutant of the MntC solute-binding protein have been determined at 2.7 and 3.5 Å resolution, respectively. The WT structure is significantly improved over the previously determined structure (PDB entry 1xvl), showing improved Mn2+ binding site parameters, disulfide bonds in all three mon ...[more]

PMID: 23519795

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Project description:Streptococcus mutans is the causative agent of dental caries, a significant concern for human health, and therefore an attractive target for therapeutics development. Previous work in our laboratory has identified a homodimeric, manganese-dependent repressor protein, SloR, as an important regulator of cariogenesis and has used site-directed mutagenesis to map functions to specific regions of the protein. Here we extend those studies to better understand the structural interaction between SloR and its operator and its effector metal ions. The results of DNase I assays indicate that SloR protects a 42-bp region of DNA that overlaps the sloABC promoter on the S. mutans UA159 chromosome, while electrophoretic mobility shift and solution binding assays indicate that each of two SloR dimers binds to this region. Real-time semiquantitative reverse transcriptase PCR (real-time semi-qRT-PCR) experiments were used to determine the individual base pairs that contribute to SloR-DNA binding specificity. Solution studies indicate that Mn(2+) is better than Zn(2+) at specifically activating SloR to bind DNA, and yet the 2.8-Å resolved crystal structure of SloR bound to Zn(2+) provides insight into the means by which selective activation by Mn(2+) may be achieved and into how SloR may form specific interactions with its operator. Taken together, these experimental observations are significant because they can inform rational drug design aimed at alleviating and/or preventing S. mutans-induced caries formation.This report focuses on investigating the SloR protein as a regulator of essential metal ion transport and virulence gene expression in the oral pathogen Streptococcus mutans and on revealing the details of SloR binding to its metal ion effectors and binding to DNA that together facilitate this expression. We used molecular and biochemical approaches to characterize the interaction of SloR with Mn(2+) and with its SloR recognition element to gain a clearer picture of the regulatory networks that optimize SloR-mediated metal ion homeostasis and virulence gene expression in S. mutans. These experiments can have a significant impact on caries treatment and/or prevention by revealing the S. mutans SloR-DNA binding interface as an appropriate target for the development of novel therapeutic interventions.

Dataset Information

Arginine 116 stabilizes the entrance to the metal ion-binding site of the MntC protein.

Publications

Arginine 116 stabilizes the entrance to the metal ion-binding site of the MntC protein.

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