1ydx
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(New page: 200px<br /><applet load="1ydx" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ydx, resolution 2.30Å" /> '''Crystal structure of...)
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Revision as of 04:35, 21 November 2007
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Crystal structure of Type-I restriction-modification system S subunit from M. genitalium
Overview
The crystal structure of the eubacteria Mycoplasma genitalium ORF MG438, polypeptide, determined by multiple anomalous dispersion and refined at, 2.3 A resolution, reveals the organization of S subunits from the Type I, restriction and modification system. The structure consists of two, globular domains, with about 150 residues each, separated by a pair of 40, residue long antiparallel alpha-helices. The globular domains correspond, to the variable target recognition domains (TRDs), as previously defined, for S subunits on sequence analysis, while the two helices correspond to, the central (CR1) and C-terminal (CR2) conserved regions, respectively., The structure of the MG438 subunit presents an overall cyclic topology, with an intramolecular 2-fold axis that superimposes the N and the C-half, parts, each half containing a globular domain and a conserved helix. TRDs, are found to be structurally related with the small domain of the Type II, N6-adenine DNA MTase TaqI. These relationships together with the, structural peculiarities of MG438, in particular the presence of the, intramolecular quasi-symmetry, allow the proposal of a model for S, subunits recognition of their DNA targets in agreement with previous, experimental results. In the crystal, two subunits of MG438 related by a, crystallographic 2-fold axis present a large contact area mainly involving, the symmetric interactions of a cluster of exposed hydrophobic residues., Comparison with the recently reported structure of an S subunit from the, archaea Methanococcus jannaschii highlights the structural features, preserved despite a sequence identity below 20%, but also reveals, important differences in the globular domains and in their disposition, with respect to the conserved regions.
About this Structure
1YDX is a Single protein structure of sequence from Mycoplasma genitalium with CL as ligand. Full crystallographic information is available from OCA.
Reference
Crystal structure of a putative type I restriction-modification S subunit from Mycoplasma genitalium., Calisto BM, Pich OQ, Pinol J, Fita I, Querol E, Carpena X, J Mol Biol. 2005 Aug 26;351(4):749-62. PMID:16038930
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