1se8

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spinqualitylabelsall models 1se8, resolution 1.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Structure of single-stranded DNA-binding protein (SSB) from D. radiodurans

Overview

Single-stranded DNA (ssDNA)-binding (SSB) proteins are uniformly required, to bind and protect single-stranded intermediates in DNA metabolic, pathways. All bacterial and eukaryotic SSB proteins studied to date, oligomerize to assemble four copies of a conserved domain, called an, oligonucleotide/oligosaccharide-binding (OB) fold, that cooperate in, nonspecific ssDNA binding. The vast majority of bacterial SSB family, members function as homotetramers, with each monomer contributing a single, OB fold. However, SSB proteins from the Deinococcus-Thermus genera are, exceptions to this rule, because they contain two OB folds per monomer. To, investigate the structural consequences of this unusual arrangement, we, have determined a 1.8-A-resolution x-ray structure of Deinococcus, radiodurans SSB. The structure shows that D. radiodurans SSB comprises two, OB domains linked by a beta-hairpin motif. The protein assembles a, four-OB-fold arrangement by means of symmetric dimerization. In contrast, to homotetrameric SSB proteins, asymmetry exists between the two OB folds, of D. radiodurans SSB because of sequence differences between the domains., These differences appear to reflect specialized roles that have evolved, for each domain. Extensive crystallographic contacts link D. radiodurans, SSB dimers in an arrangement that has important implications for, higher-order structures of the protein bound to ssDNA. This assembly, utilizes the N-terminal OB domain and the beta-hairpin structure that is, unique to Deinococcus and Thermus species SSB proteins. We hypothesize, that differences between D. radiodurans SSB and homotetrameric bacterial, SSB proteins may confer a selective advantage to D. radiodurans cells that, aids viability in environments that challenge genomic stability.

About this Structure

1SE8 is a Single protein structure of sequence from Deinococcus radiodurans. Full crystallographic information is available from OCA.

Reference

Crystal structure of the Deinococcus radiodurans single-stranded DNA-binding protein suggests a mechanism for coping with DNA damage., Bernstein DA, Eggington JM, Killoran MP, Misic AM, Cox MM, Keck JL, Proc Natl Acad Sci U S A. 2004 Jun 8;101(23):8575-80. Epub 2004 May 24. PMID:15159541

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