Attenuates Hha toxicity and regulates biofilm formation. Binds to various coding and intergenic regions of genomic DNA. Expression is autoregulated (Probable). Induced during biofilm formation. Deletion of hha and tomB, in the presence of a conjugative plasmid (R1drd19), decreases biofilm formation, cell aggregation and increases motility via flagella and motility gene expression. Hha and TomB may form a type II toxin-antitoxin (TA) system (PubMed:18545668). Belongs to the TomB family.