Open AccessActive Analyte Import Improves the Dynamic Range and Sensitivity of a Vitamin B12 Biosensor
Author(s) -
Monica P. McNerney,
Fernanda Piorino,
Cirstyn L. Michel,
Mark P. Styczynski
Publication year - 2020
Publication title -
acs synthetic biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.156
H-Index - 66
ISSN - 2161-5063
DOI - 10.1021/acssynbio.9b00429
Subject(s) - biosensor , analyte , vitamin b12 , sensitivity (control systems) , dynamic range , computational biology , computer science , chemistry , transcription factor , biological system , biochemical engineering , biochemistry , microbiology and biotechnology , biophysics , nanotechnology , biology , materials science , electronic engineering , chromatography , gene , engineering , computer vision
Cell-free systems provide a versatile platform for the development of low-cost, easy-to-use sensors for diverse analytes. However, sensor affinity dictates response sensitivity, and improving binding affinity can be challenging. Here, we describe efforts to address this problem while developing a biosensor for vitamin B 12 , a critical micronutrient. We first use a B 12 -responsive transcription factor to enable B 12 -dependent output in a cell-free reaction, but the resulting sensor responds to B 12 far above clinically relevant concentrations. Surprisingly, when expressed in cells, the same sensor mediates a much more sensitive response to B 12 . The sensitivity difference is partly due to regulated import that accumulates cytoplasmic B 12 . Overexpression of importers further improves sensitivity, demonstrating an inherent advantage of whole-cell sensors. The resulting cells can respond to B 12 in serum, can be lyophilized, and are functional in a minimal-equipment environment, showing the potential utility of whole-cell sensors as sensitive, field-deployable diagnostics.