2isy | pdb_00002isy
Crystal structure of the nickel-activated two-domain iron-dependent regulator (IdeR)
Structural highlights
Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe 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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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