Functional metagenomics screening for enzyme discovery

Our primary goal is to find new enzyme activities. We use different assay types and readouts including fluorescence, capillary-electrophoresis, and mass spectrometry to look for enzymes of interest within our collection of (meta)genomic libraries. We take a high-throughput functional approach to screening. This bypasses the use of computational methods that rely mostly on known protein scaffolds, enabling us to find entirely new enzyme families. We have both an applied and fundamental motive and seek to find enzymes that can act as analytical tools as well as help better understand biological processes.


Diagrams showing RNaseH2 and DNA ligase activity assays

Example of screening results for RNaseH2 (A) and DNA ligase (B) activities.
Double stranded fluorescently labelled oligonucleotides were used to screen a fosmid library for RNaseH2 (A) and DNA ligase (B) enzymes. Screening reactions were run on multiple capillary electrophoresis (CE) to detect hits. CE profiles for each reaction was compared to a negative (‘neg’) and positive control (‘RNAseH2’ or ‘9N DNA ligase’). Each screen led to hits among which clones H4 and C2.


Scatter plot of relative fluorescence units (RFUs) for different clones.

Screening for sugar-specific sulfatases.
A fosmid library was screened for sulfatases using a sulfated-monosaccharide linked to a fluorophore and a coupled-assay. Fluorescence values above the mean + 6σ (black line) were considered ‘hits’. Control lysates (grey circles) were assayed along with the metagenomic clones (blue circles) from the primary screen.