Limits...
The Metal-Dependent Regulators FurA and FurB from Mycobacterium Tuberculosis.

Lucarelli D, Vasil ML, Meyer-Klaucke W, Pohl E - Int J Mol Sci (2008)

Bottom Line: Although both belong to the same family, they share only approximately 25% sequence identity and as a consequence, they differ significantly in some of their key biological functions.FurB in contrast requires Zn(2+) rather than Fe(2+), to bind to its target sequence in regulated genes, which include those involved in Zn(2+)-homeostasis.Recent biochemical, crystallographic and spectroscopic data have now shed light on the activation and metal discrimination mechanisms in this protein family.

View Article: PubMed Central - PubMed

Affiliation: European Molecular Biology Laboratory, Hamburg Outstation, Notkestr. 85, D-22603 Hamburg, Germany. E-Mails: Debora.Lucarelli@cancer.org.uk (D. L.); wolfram@embl-hamburg.de (W. M-K.).

ABSTRACT
The ferric uptake regulators (Fur) form a large family of bacterial metal-activated DNA-binding proteins that control a diverse set of genes at the transcriptional level. Mycobacterium tuberculosis, the causative agent of tuberculosis, expresses two members of the Fur family, designated FurA and FurB. Although both belong to the same family, they share only approximately 25% sequence identity and as a consequence, they differ significantly in some of their key biological functions. FurA appears to be a specialized iron-dependent regulator that controls the katG gene, which encodes for a catalase-peroxidase involved in the response of M. tuberculosis to oxidative stress. KatG is also the key mycobacterial enzyme responsible for the activation of the first-line tuberculosis drug Isoniazid. FurB in contrast requires Zn(2+) rather than Fe(2+), to bind to its target sequence in regulated genes, which include those involved in Zn(2+)-homeostasis. Recent biochemical, crystallographic and spectroscopic data have now shed light on the activation and metal discrimination mechanisms in this protein family.

No MeSH data available.


Related in: MedlinePlus

Ribbon diagrams of the crystal structure of Fur homologues. All three proteins are dimers with the N-terminal DNA-binding domain depicted in green and the C-terminal dimerization domain shown in red. All Zn2+-ions are shown as golden spheres. (a) FurB in complex with Zn2+ solved at 2.7 Å resolution, the putative regulatory sites are labeled Zn1 and Zn1', the structural sites are labeled Zn2 and Zn2', respectively. The labels for the third site were omitted for clarity [43]. (b)Furpa complexed with Zn2+ [47]. (c)apo-PerRbs with its putative structural Zn2+-site [46]. All Figures were produced with PyMol [50].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2630230&req=5

f3-ijms-9-1548: Ribbon diagrams of the crystal structure of Fur homologues. All three proteins are dimers with the N-terminal DNA-binding domain depicted in green and the C-terminal dimerization domain shown in red. All Zn2+-ions are shown as golden spheres. (a) FurB in complex with Zn2+ solved at 2.7 Å resolution, the putative regulatory sites are labeled Zn1 and Zn1', the structural sites are labeled Zn2 and Zn2', respectively. The labels for the third site were omitted for clarity [43]. (b)Furpa complexed with Zn2+ [47]. (c)apo-PerRbs with its putative structural Zn2+-site [46]. All Figures were produced with PyMol [50].

Mentions: The crystal structure of FurB in complex with Zn2+ determined at a resolution of 2.7 Å revealed the familiar two-domain structure with the N-terminal DNA-binding domain composed of a three-helix bundle followed by a short antiparallel β-sheet, and the C-terminal metal-binding and dimerization domain [43]. Although the overall fold is similar to the first crystal structure of another member of the Fur-family (Fur from P. aeruginosa, Furpa [47]) there are noteworthy differences in domain orientation as well as metal binding sites. Overall, the individual domains of FurB are very similar with the exception that the DNA-binding domain of FurB lacks the N-terminal helix that is present in Furpa and Furec [48]. However, the relative orientations of their two domains are very different (Figure 3a-c). The FurB homodimer adopts a much more open conformation where the DNA-binding domains are further separated and the DNA-recognition helices (helix 3, residues 45–58 in FurB in Figure 2) are almost collinear to each other. While the amino-acid sequence of the DNA binding helix is well conserved within the Fur family there are sufficient differences to enable DNA sequence specific recognition. The mobility of DNA-binding domains with respect to the dimer interface is also highlighted by the crystal structure of apo-PerRbs which shows a similar fold but a distinctively different domain orientation [46]. It should be noted that such domain motions can also be caused by packing effects as have been observed previously in the crystal structures of apo- and holo-DtxR [49].


The Metal-Dependent Regulators FurA and FurB from Mycobacterium Tuberculosis.

Lucarelli D, Vasil ML, Meyer-Klaucke W, Pohl E - Int J Mol Sci (2008)

Ribbon diagrams of the crystal structure of Fur homologues. All three proteins are dimers with the N-terminal DNA-binding domain depicted in green and the C-terminal dimerization domain shown in red. All Zn2+-ions are shown as golden spheres. (a) FurB in complex with Zn2+ solved at 2.7 Å resolution, the putative regulatory sites are labeled Zn1 and Zn1', the structural sites are labeled Zn2 and Zn2', respectively. The labels for the third site were omitted for clarity [43]. (b)Furpa complexed with Zn2+ [47]. (c)apo-PerRbs with its putative structural Zn2+-site [46]. All Figures were produced with PyMol [50].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2630230&req=5

f3-ijms-9-1548: Ribbon diagrams of the crystal structure of Fur homologues. All three proteins are dimers with the N-terminal DNA-binding domain depicted in green and the C-terminal dimerization domain shown in red. All Zn2+-ions are shown as golden spheres. (a) FurB in complex with Zn2+ solved at 2.7 Å resolution, the putative regulatory sites are labeled Zn1 and Zn1', the structural sites are labeled Zn2 and Zn2', respectively. The labels for the third site were omitted for clarity [43]. (b)Furpa complexed with Zn2+ [47]. (c)apo-PerRbs with its putative structural Zn2+-site [46]. All Figures were produced with PyMol [50].
Mentions: The crystal structure of FurB in complex with Zn2+ determined at a resolution of 2.7 Å revealed the familiar two-domain structure with the N-terminal DNA-binding domain composed of a three-helix bundle followed by a short antiparallel β-sheet, and the C-terminal metal-binding and dimerization domain [43]. Although the overall fold is similar to the first crystal structure of another member of the Fur-family (Fur from P. aeruginosa, Furpa [47]) there are noteworthy differences in domain orientation as well as metal binding sites. Overall, the individual domains of FurB are very similar with the exception that the DNA-binding domain of FurB lacks the N-terminal helix that is present in Furpa and Furec [48]. However, the relative orientations of their two domains are very different (Figure 3a-c). The FurB homodimer adopts a much more open conformation where the DNA-binding domains are further separated and the DNA-recognition helices (helix 3, residues 45–58 in FurB in Figure 2) are almost collinear to each other. While the amino-acid sequence of the DNA binding helix is well conserved within the Fur family there are sufficient differences to enable DNA sequence specific recognition. The mobility of DNA-binding domains with respect to the dimer interface is also highlighted by the crystal structure of apo-PerRbs which shows a similar fold but a distinctively different domain orientation [46]. It should be noted that such domain motions can also be caused by packing effects as have been observed previously in the crystal structures of apo- and holo-DtxR [49].

Bottom Line: Although both belong to the same family, they share only approximately 25% sequence identity and as a consequence, they differ significantly in some of their key biological functions.FurB in contrast requires Zn(2+) rather than Fe(2+), to bind to its target sequence in regulated genes, which include those involved in Zn(2+)-homeostasis.Recent biochemical, crystallographic and spectroscopic data have now shed light on the activation and metal discrimination mechanisms in this protein family.

View Article: PubMed Central - PubMed

Affiliation: European Molecular Biology Laboratory, Hamburg Outstation, Notkestr. 85, D-22603 Hamburg, Germany. E-Mails: Debora.Lucarelli@cancer.org.uk (D. L.); wolfram@embl-hamburg.de (W. M-K.).

ABSTRACT
The ferric uptake regulators (Fur) form a large family of bacterial metal-activated DNA-binding proteins that control a diverse set of genes at the transcriptional level. Mycobacterium tuberculosis, the causative agent of tuberculosis, expresses two members of the Fur family, designated FurA and FurB. Although both belong to the same family, they share only approximately 25% sequence identity and as a consequence, they differ significantly in some of their key biological functions. FurA appears to be a specialized iron-dependent regulator that controls the katG gene, which encodes for a catalase-peroxidase involved in the response of M. tuberculosis to oxidative stress. KatG is also the key mycobacterial enzyme responsible for the activation of the first-line tuberculosis drug Isoniazid. FurB in contrast requires Zn(2+) rather than Fe(2+), to bind to its target sequence in regulated genes, which include those involved in Zn(2+)-homeostasis. Recent biochemical, crystallographic and spectroscopic data have now shed light on the activation and metal discrimination mechanisms in this protein family.

No MeSH data available.


Related in: MedlinePlus