title: Biomineralization of uranium by PhoY phosphatase activity aids cell survival in Caulobacter crescentus.
abstract: Caulobacter crescentus is known to tolerate high levels of uranium [U(VI)], but its detoxification mechanism is poorly understood. Here we show that C. crescentus is able to facilitate U(VI) biomineralization through the formation of U-Pi precipitates via its native alkaline phosphatase activity. The U-Pi precipitates, deposited on the cell surface in the form of meta-autunite structures, have a lower U/Pi ratio than do chemically produced precipitates. The enzyme that is responsible for the phosphatase activity and thus the biomineralization process is identified as PhoY, a periplasmic alkaline phosphatase with broad substrate specificity. Furthermore, PhoY is shown to confer a survival advantage on C. crescentus toward U(VI) under both growth and nongrowth conditions. Results obtained in this study thus highlight U(VI) biomineralization as a resistance mechanism in microbes, which not only improves our understanding of bacterium-mineral interactions but also aids in defining potential ecological niches for metal-resistant bacteria.
authors.affiliation: Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California, USA.
authors.forename: Mimi C
authors.initials: MC
authors.lastname: Yung
authors.affiliation: Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California, USA jiao1@llnl.gov.
authors.forename: Yongqin
authors.initials: Y
authors.lastname: Jiao
mesh_terms: D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D016935:Caulobacter crescentus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D050296:Microbial Viability; D019897:Periplasm / Q000201:enzymology / Q000378:metabolism; D014501:Uranium / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D014501:Uranium; D000469:Alkaline Phosphatase