BB-rel@ldeleger:BB-rel-16514151 JSONTXT

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bionlp-ost-19-BB-rel-dev

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Id Subject Object Predicate Lexical cue
T1 0-75 Title denotes Hg(II) sequestration and protection by the MerR metal-binding domain (MBD).
T2 76-1411 Paragraph denotes MerR, the metalloregulator of the bacterial mercury resistance (mer) operon, binds Hg(II) with high affinity. To study the mechanism of metal-induced activation, a small protein was previously engineered embodying in a single polypeptide the metal-binding domain (MBD) ordinarily formed between two monomers of MerR. Here the physiological and biochemical properties of MBD expressed on the cell surface or in the cytosol were examined, to better understand the environments in which specific metal binding can occur with this small derivative. Over 20 000 surface copies of MBD were expressed per Escherichia coli cell, with metal stoichiometries of approximately 1.0 Hg(II) per MBD monomer. Cells expressing MBD on their surface in rich medium bound 6.1-fold more Hg(II) than those not expressing MBD. Although in nature cells use the entire mer operon to detoxify mercury, it was interesting to note that cells expressing only MBD survived Hg(II) challenge and recovered more quickly than cells without MBD. Cell-surface-expressed MBD bound Hg(II) preferentially even in the presence of a 22-fold molar excess of Zn(II) and when exposed to equimolar Cd(II) in addition. MBD expressed in the cystosol also afforded improved survival from Hg(II) exposure for E. coli and for the completely unrelated bacterium Deinococcus radiodurans.
T3 120-138 Phenotype denotes mercury resistance
T4 140-143 Phenotype denotes mer
T5 674-690 Microorganism denotes Escherichia coli
T6 810-821 Habitat denotes rich medium
T7 1336-1343 Microorganism denotes E. coli
T8 1387-1410 Microorganism denotes Deinococcus radiodurans