Important for reducing fluoride concentration in the cell, thus reducing its toxicity. Could be a dual-topology protein, which inserts into the membrane in two opposite orientations. May form an antiparallel homodimer in the inner membrane. By fluoride, via a fluoride-responsive riboswitch. Mutants show increased sensitivity to fluoride (PubMed:22194412). Deletion of pagP (crcA), cspE and crcB increases sensitivity to camphor and exacerbates the nucleoid morphology defects of the topoisomerase IV temperature-sensitive mutants (PubMed:12904550). Overexpression of pagP (crcA), cspE and crcB leads to camphor resistance, chromosome condensation and suppression of growth defects of mukB mutants (PubMed:8844142). Overexpression also increases levels of plasmid supercoiling, results in increased resistance to nalidixic acid in gyrase and topoisomerase IV temperature-sensitive mutants and affects the regulation of several genes (PubMed:12904550). Belongs to the CrcB (TC 9.B.71) family.