This family of proteins is found exclusively in epsilon-proteobacteria. Proteins in this family are approximately 180 amino acids in length. The structure of HobA is a modified Rossmann fold consisting of a five-stranded parallel beta-sheet (beta1-5) flanked on one side by alpha-2, alpha-3 and alpha-6 helices and alpha-4 and alpha-5 on the other. The alpha-1 helix is extended away from and has minimal interaction with the globular part of the protein. Four monomers interact to form a tetrameric molecule. Four calcium atoms bind to the tetramer and these binding sites may have functional relevance. The function of HobA is to regulate DNA replication and its does this by binding to DNA-A, but the exact mechanism of how this regulation occurs is purely speculative

1: Structural similarity between the DnaA-binding proteins HobA (HP1230) from Helicobacter pylori and DiaA from Escherichia coli. Natrajan G, Hall DR, Thompson AC, Gutsche I, Terradot L; Mol Microbiol. 2007;65:995-1005. PMID:17683397