| Comment | Members of this family feature an N-terminal signal sequence, small size, and two invariant Cys residues, 10-20 residues apart. One member of this family, UrcA from the aerobic bacterium Caulobacter crescentus, is expressed so highly in response to uranium, but not other heavy metals, that a genetically engineered strain expressing green fluorescent protein in place of UrcA serves as a biodetector for micromolar uranyl ion. Caulobacter crescentus tolerates high levels of U(VI) exposure by mineralizing the uranium. UrcA and its homologs may participate in such a process. |
