BOF: a novel family of bacterial OB‐fold proteins

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Abstract
Using top‐of‐the‐line fold recognition methods, we assigned an oligonucleotide/oligosaccharide‐binding (OB)‐fold structure to a family of previously uncharacterized hypothetical proteins from several bacterial genomes. This novel family of bacterial OB‐fold (BOF) proteins present in a number of pathogenic strains encompasses sequences of unknown function from DUF388 (in Pfam database) and COG3111. The BOF proteins can be linked evolutionarily to other members of the OB‐fold nucleic acid‐binding superfamily (anticodon‐binding and single strand DNA‐binding domains), although they probably lack nucleic acid‐binding properties as implied by the analysis of the potential binding site. The presence of conserved N‐terminal predicted signal peptide indicates that BOF family members localize in the periplasm where they may function to bind proteins, small molecules, or other typical OB‐fold ligands. As hypothesized for the distantly related OB‐fold containing bacterial enterotoxins, the loss of nucleotide‐binding function and the rapid evolution of the BOF ligand‐binding site may be associated with the presence of BOF proteins in mobile genetic elements and their potential role in bacterial pathogenicity.