1h9j
From Proteopedia
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TWO CRYSTAL STRUCTURES OF THE CYTOPLASMIC MOLYBDATE-BINDING PROTEIN MODG SUGGEST A NOVEL COOPERATIVE BINDING MECHANISM AND PROVIDE INSIGHTS INTO LIGAND-BINDING SPECIFICITY. PHOSPHATE-GROWN FORM WITH MOLYBDATE AND PHOSPHATE BOUND
Overview
The X-ray structures of the cytoplasmic molybdate-binding protein ModG, from Azotobacter vinelandii in two different crystal forms have been, determined. For such a small protein it is remarkably complex. Each 14.3, kDa subunit contains two small beta-barrel domains, which display an, OB-fold motif, also seen in the related structure of ModE, a, molybdenum-dependent transcriptional regulator, and very recently in the, Mop protein that, like ModG, has been implicated in molybdenum homeostasis, within the cell. In contrast to earlier speculation, the functional unit, of ModG is actually not a dimer (as in ModE), but a trimer capable of, binding a total of eight molybdate molecules that are distributed between, two disparate types of site. All the binding sites are located at subunit, interfaces, with one type lying on a crystallographic 3-fold axis, whilst, the other lies between pairs of subunits. The two types of site are linked, by short hydrogen bond networks that may suggest a cooperative binding, mechanism. A superposition of two subunits of the ModG trimer on the, apo-ModE dimer allows the probable locations of the molybdate-binding, sites of the latter to be assigned. Through structural comparisons with, other oxyanion-binding proteins, including Mop and ModE, it is possible to, speculate about ligand-binding affinities, selectivity and evolution., Copyright 12001 Academic Press.
About this Structure
1H9J is a Single protein structure of sequence from Azotobacter vinelandii with and as ligands. Known structural/functional Sites: and . Full crystallographic information is available from OCA.
Reference
Two crystal structures of the cytoplasmic molybdate-binding protein ModG suggest a novel cooperative binding mechanism and provide insights into ligand-binding specificity., Delarbre L, Stevenson CE, White DJ, Mitchenall LA, Pau RN, Lawson DM, J Mol Biol. 2001 May 18;308(5):1063-79. PMID:11352591
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