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Title: A microbial sensor for organophosphate hydrolysis exploiting an engineered specificity switch in a transcription factor

A whole-cell biosensor utilizing a transcription factor (TF) is an effective tool for sensitive and selective detection of specialty chemicals or anthropogenic molecules, but requires an access to an expanded repertoire of TFs. Using ligand docked homology models for binding pocket identification, assisted by conservative mutations in the pocket, we engineered a novel specificity in an Acinetobacter TF, PobR, to ‘sense’ a chemical p-nitrophenol (pNP) and measured the response via a fluorescent protein reporter expressed from a PobR promoter. Out of 10 7 variants of PobR, four were active when pNP was added as an inducer, with two mutants showing a specificity switch from the native effector 4-hydroxybenzoate (4HB). One of the mutants, pNPmut1 was then used to create a smart microbial cell responding to pNP production and detect hydrolysis of an insecticide, paraoxon, in a coupled assay involving phosphotriesterase (PTE) enzyme expressed from a separate promoter. We show that the fluorescence of the cells correlated with the catalytic efficiency of PTE variants, each cell expressed. High selectivity for similar molecules (4HB vs pNP), high sensitivity for pNP detection (~2 μM) and agreement of apo- and holo- structures of PobR scaffold with computational models are notable successes presented in thismore » work.« less
 [1] ;  [1] ;  [2] ;  [2] ;  [2] ;  [3] ;  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States); Univ. of Chicago, IL (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 0305-1048
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Nucleic Acids Research
Additional Journal Information:
Journal Volume: 44; Journal Issue: 17; Journal ID: ISSN 0305-1048
Oxford University Press
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES; Biological Science; whole-cell biosensor, transcription factor, protein design, high throughput screening, paraoxon, nerve agent, flow cytometry
OSTI Identifier: