Table 1.
Comparison of unique features seen with genetically encoded ATP biosensors.
| Genetically Encoded ATP Biosensors | ||||
|---|---|---|---|---|
| Biosensor | Technique | Mechanism | Advantage | Disadvantage |
| ATEAM [146] | FRET | Adenosine 5′-triphosphate indication based on ϵ subunit for analytical measurement; ATP binding causes an increase in Forster resonance energy transfer between a CFP and YFP and results in a higher wavelength release; comprised of bacterial ϵ subunit of bacterial ATP synthase with cyan and yellow donor/acceptor pairs at N and C terminals, respectively | Qualitative/quantitative; spatiotemporal resolution |
Sensitive to acidic pH, thus limiting which cellular subcomponent cell can use; can undergo glycosylation in ER and Golgi which inhibits its ability to bind to ATP |
| GO-ATEAM [143] | FRET | Similar to ATEAM but CFP and YFP are replaced by green (GFP) and orange (mKOk) fluorescent pair, respectively | ||
| BTEAM [155] | BRET | Composed of e subunit of bacterial ATP synthase flanked by Venus at the N terminal and Nanoluciferase at the C terminal; emitted light is produced by Nanoluciferase because oxidation of luciferin cases emission of photons; capacity of luciferin to emit light is directly correlated to amount of ATP available | Qualitative/quantitative; spatiotemporal resolution; no need for laser, as light emission come from enzymatic reaction after administration of luciferase substrate; avoid generation of autofluorescent and phototoxicity; very sensitive; simplicity of assay; can add localization signals to target cell subcompartments | Luciferin limitation due to inhibition of reaction from other drugs; limits potential with some drug development; enzymatic and substrate concentration limitations; transfection efficiency limitations; optimization required for maximal detection; some luciferases produce ATP from pools of ADP |
| ARSeNL [167] | BRET | ATP detection via ratiometric mScarlet-NanoLuc sensor, similar to BTEAM | ||
| QUEEN [168] | Ratiometric | Quantitative evaluator of cellular energy; cpFP is inserted between two a helices of ϵ subunit of ATP synthase with linkers | similar results to bioluminescence luciferase assays | Modest pH sensitivity |
| iATPSnFR [160] | Intensiometric | Intensity-based ATP-sensing fluorescent reporter consists of circularly superfolder GFP between 2 alpha helices of ϵ subunit of bacterial ATP synthase; when ATP binds, rapid increase in fluorescence occurs | spatiotemporal resolution | Modest pH sensitivity |
| Syn-ATP [153] | Bioluminescence | Luciferin-reaction based; synaptophysin targets synaptic vesicle proteins and mCherry helps to determine total amount of luciferase using a luminescence/fluorescent ratio | Qualitative/quantitative; only used for synaptic vesicles | No spatiotemporal resolution; some luciferases produce ATP from pools of ADP |
| MaLion [161] | Intensiometric | multiple constructs created to target subcellular compartments (cytosol, mitochondria, nucleus); consists of a fused ϵ subunit of bacterial ATP synthase to red, blue, or green | Qualitative/quantitative; spatiotemporal resolution; has organelle-targeted specific ATP estimations; the higher the ATP, the brighter the fluorescence; low pH sensitivity | Potential phototoxicity due to fluorescence emission in living cells; transfection efficiency in hard to transfect cells |
| Perceval [164] | Ratiometric | Based on estimation of ADP/ATP; composed of GlnK1 (a bacterial regulatory protein) linked to Venus; GlnK1 undergoes a conformational change when bound to ATP | Qualitative/quantitative; spatiotemporal resolution; no conformational change when bound to ADP | Some pH sensitivity |