2sob

Publication Abstract from PubMed

Similar folds often occur in proteins with dissimilar sequences. The OB-fold forms a part of the structures of at least seven non-homologous proteins that share either oligonucleotide or oligosaccharide binding functions. A 1-103 fragment corresponding to the OB-fold of the 149 amino acid residue staphylococcal nuclease gives NMR spectra characteristic of an unfolded protein, i.e. the wild-type nuclease sequence is insufficient to maintain a stable tertiary structure in the absence of the C-terminal one-third of this single-domain protein. By contrast, the 1-103 fragment of nuclease with the mutations Val66Leu and Gly88Val adopts a stable tertiary structure. The NMR solution structure of this latter fragment is a close variation of the OB-fold found in the X-ray structure of the parent protein. The Val66Leu and Gly88Val mutations appear to stabilize tertiary structure by consolidating the hydrophobic core of the nuclease OB-fold sub-domain. Taken together, these results suggest that recurrent structural motifs such as the OB-fold may in some cases represent vestiges of autonomous folding units that, during evolution, have become integrated into more complex cooperative folding domains.

NMR structure of a stable "OB-fold" sub-domain isolated from staphylococcal nuclease.,Alexandrescu AT, Gittis AG, Abeygunawardana C, Shortle D J Mol Biol. 1995 Jul 7;250(2):134-43. PMID:7608966^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.