2isy

From Proteopedia

Revision as of 13:23, 20 November 2007

Crystal structure of the nickel-activated two-domain iron-dependent regulator (IdeR)

Overview

The iron-dependent regulator IdeR is a key transcriptional regulator of, iron uptake in Mycobacterium tuberculosis. In order to increase our, insight into the role of the SH3-like third domain of this essential, regulator, the metal-binding and DNA-binding properties of two-domain IdeR, (2D-IdeR) whose SH3-like domain has been truncated were characterized. The, equilibrium dissociation constants for Co2+ and Ni2+ activation of 2D-IdeR, for binding to the fxbA operator and the DNA-binding affinities of 2D-IdeR, in the presence of excess metal ions were estimated using fluorescence, spectroscopy. 2D-IdeR binds to fxbA operator DNA with similar affinity as, full-length IdeR in the presence of excess metal ion. However, the Ni2+, concentrations required to activate 2D-IdeR for DNA binding appear to be, smaller than that for full-length IdeR while the concentration of Co2+, required for activation remains the same. We have determined the crystal, structures of Ni2+-activated 2D-IdeR at 1.96 A resolution and its double, dimer complex with the mbtA-mbtB operator DNA in two crystal forms at 2.4, A and 2.6 A, the highest resolutions for DNA complexes for any structures, of iron-dependent regulator family members so far. The 2D-IdeR-DNA complex, structures confirm the specificity of Ser37 and Pro39 for thymine bases, and suggest preferential contacts of Gln43 to cytosine bases of the DNA., In addition, our 2D-IdeR structures reveal a remarkable property of the, TEV cleavage sequence remaining after removal of the C-terminal His6. This, C-terminal tail promotes crystal contacts by forming a beta-sheet with the, corresponding tail of neighboring subunits in two unrelated structures of, 2D-IdeR, one with and one without DNA. The contact-promoting properties of, this C-terminal TEV cleavage sequence may be beneficial for crystallizing, other proteins.

About this Structure

2ISY is a Single protein structure of sequence from Mycobacterium tuberculosis with NI and PO4 as ligands. Full crystallographic information is available from OCA.

Reference

Crystal structures, metal activation, and DNA-binding properties of two-domain IdeR from Mycobacterium tuberculosis., Wisedchaisri G, Chou CJ, Wu M, Roach C, Rice AE, Holmes RK, Beeson C, Hol WG, Biochemistry. 2007 Jan 16;46(2):436-47. PMID:17209554

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