An artificial metalloenzyme biosensor can detect ethylene gas in fruits and Arabidopsis leaves

Abstract

Enzyme biosensors are useful tools that can monitor rapid changes in metabolite levels in real-time. However, current approaches are largely constrained to metabolites within a limited chemical space. With the rising development of artificial metalloenzymes (ArM), a unique opportunity exists to design biosensors from the ground-up for metabolites that are difficult to detect using current technologies. Here we present the design and development of the ArM ethylene probe (AEP), where an albumin scaffold is used to solubilize and protect a quenched ruthenium catalyst. In the presence of the phytohormone ethylene, cross metathesis can occur to produce fluorescence. The probe can be used to detect both exogenous- and endogenous-induced changes to ethylene biosynthesis in fruits and leaves. Overall, this work represents an example of an ArM biosensor, designed specifically for the spatial and temporal detection of a biological metabolite previously not accessible using enzyme biosensors.

Artificial Metalloenzymes: From Selective Chemical Transformations to Biochemical Applications

“…These reaction networks only work when an ArM is used, but not with their cofactors alone. By extending this concept, ArMs have been used in and on mammalian cells for pharmaceutical applications [ 78 , 136 , 139 , 140 , 141 ]. Thus, we believe that ArMs have great potential as catalysts for organic synthesis and as chemical biology tools for pharmaceutical applications.…”

“…To explore the application of ArMs as diagnostic tools, 118 ·HSA was modified with 127 to give an ethylene probe 126 ·HSA ( Figure 26 ) [ 140 ]. In the presence of ethylene, cross-metathesis of 126 with ethylene occurs to dissociate the fluorescent quencher 127 , recovering the fluorescence of the coumarin moiety.…”

Exploring and Adapting the Molecular Selectivity of Artificial Metalloenzymes

“…To spearhead this area of research, our group has developed an ArM biosensor for the detection of ethylene gas. 203 As an essential plant hormone, ethylene is an important metabolite that regulates plant growth, immunity, and senescence. 204 To detect this in a spatiotemporal manner, an ethylene-sensing ArM (AEP) was devised as depicted in Figure 9A.…”

“…C) Fluorescent images of ripe kiwifruit slices to highlight the capabilities of AEP to detect endogenously induced ethylene. Reproduced with permission from Springer Nature 203.…”

Unlocking the therapeutic potential of artificial metalloenzymes

“…8, our group has developed one of the first examples of an ArM-based biosensor, which is used to detect the plant hormone, ethylene gas. 106) Based on the approach shown in Fig. 8a, the albumin scaffold is used to solubilize and protect a quenched ruthenium catalyst complex.…”