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OB(oligonucleotide/oligosaccharide binding)-fold: common structural and functional solution for non-homologous
1MRC Laboratory of Molecular Biology, Cambridge, UK.
The EMBO Journal
|March 1, 1993
Summary
Researchers identified a novel protein fold, the OB-fold, common in proteins binding nucleic acids and sugars. This conserved structure, despite sequence variations, has implications for understanding protein function and evolution.
Area of Science:
- Structural biology
- Molecular biology
- Biochemistry
Background:
- A conserved protein fold, termed the OB-fold, has been identified in diverse proteins.
- These proteins include staphylococcal nuclease, asp-tRNA synthetase, heat-labile enterotoxin, and verotoxin-1.
- The OB-fold is implicated in binding oligonucleotides or oligosaccharides.
Purpose of the Study:
- To describe the structural determinants of the OB-fold.
- To explain how divergent protein sequences adopt this common fold.
- To re-evaluate the structure of gene 5 ssDNA binding protein in light of the OB-fold.
Main Methods:
- Comparative structural analysis of four proteins exhibiting the OB-fold.
- Analysis of protein sequence alignments.
- Examination of nucleotide and sugar binding sites.
Main Results:
- The OB-fold features a five-stranded beta-sheet forming a closed beta-barrel, capped by an alpha-helix.
- Structural superimposition shows conserved fold architecture (1.4-2.2 A r.m.s. deviation) despite sequence dissimilarity.
- Binding sites for nucleotides/sugars are consistently located on the beta-barrel surface.
Conclusions:
- The OB-fold's determinants facilitate its adoption by varied protein sequences.
- The OB-fold represents a conserved structural motif for nucleic acid and carbohydrate binding.
- Structural similarities suggest gene 5 ssDNA binding protein may also adopt an OB-fold.