ssDNA-binding protein that probably contributes to the ionizing radiation resistance of D.geothermalis. Plays a role in DNA repair and genome reconstitution, in a RecA-independent process, and is necessary for recovery from severe genomic fragmentation as a result of exposure to severe levels of ionizing radiation (Probable). Binds single-stranded DNA but not duplex DNA. Homopentamer; arranged in a ring-structure. Induced to high levels following extreme ionizing radiation exposure. Also highly induced in response to desiccation stress (By similarity). Contains a novel ssDNA-binding fold, which is structurally and topologically distinct from the OB-fold universally found in standard SSB proteins. The disordered C-terminus of DdrB may mediate interactions with other proteins important for DNA damage recovery.