4m32 | pdb_00004m32

Crystal structure of gated-pore mutant D138N of second DNA-Binding protein under starvation from Mycobacterium smegmatis

spinqualitylabelsall models 4m32, resolution 1.86Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4m32 is a 4 chain structure with sequence from Mycolicibacterium smegmatis MC2 155. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.86Å Ligands: CL, FE2, MG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function A0QXB7_MYCS2 Publication Abstract from PubMed Dps (DNA-binding protein from starved cells) are dodecameric assemblies belonging to the ferritin family that can bind DNA, carry out ferroxidation, and store iron in their shells. The ferritin-like trimeric pore harbors the channel for the entry and exit of iron. By representing the structure of Dps as a network we have identified a charge-driven interface formed by a histidine aspartate cluster at the pore interface unique to Mycobacterium smegmatis Dps protein, MsDps2. Site-directed mutagenesis was employed to generate mutants to disrupt the charged interactions. Kinetics of iron uptake/release of the wild type and mutants were compared. Crystal structures were solved at a resolution of 1.8-2.2 A for the various mutants to compare structural alterations vis a vis the wild type protein. The substitutions at the pore interface resulted in alterations in the side chain conformations leading to an overall weakening of the interface network, especially in cases of substitutions that alter the charge at the pore interface. Contrary to earlier findings where conserved aspartate residues were found crucial for iron release, we propose here that in the case of MsDps2, it is the interplay of negative-positive potentials at the pore that enables proper functioning of the protein. In similar studies in ferritins, negative and positive patches near the iron exit pore were found to be important in iron uptake/release kinetics. The unique ionic cluster in MsDps2 makes it a suitable candidate to act as nano-delivery vehicle, as these gated pores can be manipulated to exhibit conformations allowing for slow or fast rates of iron release. A histidine aspartate ionic lock gates the iron passage in miniferritins from Mycobacterium smegmatis.,Williams SM, Chandran AV, Vijayabaskar MS, Roy S, Balaram H, Vishveshwara S, Vijayan M, Chatterji D J Biol Chem. 2014 Apr 18;289(16):11042-58. doi: 10.1074/jbc.M113.524421. Epub, 2014 Feb 26. PMID:24573673 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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