2isy | pdb_00002isy
Crystal structure of the nickel-activated two-domain iron-dependent regulator (IdeR)
Structural highlights
Function[IDER_MYCTU] Metal-dependent DNA-binding protein that controls transcription of many genes involved in iron metabolism. Acts as a repressor of siderophore biosynthesis and as a positive modulator of iron storage. Also regulates expression of transporters, proteins involved in siderophore synthesis, iron storage and transcriptional regulators.[1] [2] 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[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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