This family contains OB-fold domains that bind to nucleic acids . The family includes the anti-codon binding domain of lysyl, aspartyl, and asparaginyl -tRNA synthetases (See PF00152). Aminoacyl-tRNA synthetases catalyse the addition of an amino acid to the appropriate tRNA molecule EC:6.1.1.-. This family also includes part of RecG helicase involved in DNA repair. Replication factor A is a hetero-trimeric complex, that contains a subunit in this family [2,3]. This domain is also found at the C-terminus of bacterial DNA polymerase III alpha chain.
The OB-fold (oligonucleotide/oligosaccharide-binding fold) is found in all three kingdoms and its common architecture presents a binding face that has adapted to bind different ligands. The OB-fold is a five/six-stranded closed beta-barrel formed by 70-80 amino acid residues. The strands are connected by loops of varying length which form the functional appendages of the protein. The majority of OB-fold proteins use the same face for ligand binding or as an active site. Different OB-fold proteins use this 'fold-related binding face' to, variously, bind oligosaccharides, oligonucleotides, proteins, metal ions and catalytic substrates.
Ruff M, Krishnaswamy S, Boeglin M, Poterszman A, Mitschler A, Podjarny A, Rees B, Thierry JC, Moras D; , Science 1991;252:1682-1689.: Class II aminoacyl transfer RNA synthetases: crystal structure of yeast aspartyl-tRNA synthetase complexed with tRNA(Asp). PUBMED:2047877 EPMC:2047877 .