A Small-Molecule Approach Enables RNA Aptamers to Function as Sensors for Reactive Inorganic Targets

Area of Science:

• Biochemistry
• Molecular Biology
• Chemical Biology

Background:

• Fluorescent light-up aptamer (FLAP) systems offer genetically encodable biosensing capabilities.
• Current FLAP applications require specific aptamer engineering or in vitro selection for each target, posing challenges for inorganic or short-lived species detection.

Purpose of the Study:

• To develop a versatile FLAP system capable of detecting unique, non-fluorogenic, and reactive inorganic molecules.
• To overcome the limitations of sequence-specific aptamer discovery for challenging analytes.

Main Methods:

• Engineered RNA aptamers (Baby Spinach, Broccoli, Squash) with functionalized pre-ligands.
• Utilized reactive inorganic species (H2S/HS-, H2O2) to convert pre-ligands into native ligands, triggering fluorescence.
• Adapted the system for whole-cell sensing in Escherichia coli.

Main Results:

• Demonstrated specific conversion of pre-ligands to fluorescent ligands by H2S/HS- and H2O2.
• Successfully created whole-cell biosensors in E. coli that fluoresce in response to these inorganic species.
• Validated the small-molecule approach for detecting reactive inorganics without new aptamer selection.

Conclusions:

• The developed small-molecule strategy significantly broadens the applicability of FLAP systems to detect reactive inorganic and short-lived species.
• This method eliminates the need for laborious aptamer engineering for diverse molecular targets.
• Paves the way for advanced whole-cell sensors with enhanced detection capabilities.