1
|
Rich MH, Sharrock AV, Mulligan TS, Matthews F, Brown AS, Lee-Harwood HR, Williams EM, Copp JN, Little RF, Francis JJB, Horvat CN, Stevenson LJ, Owen JG, Saxena MT, Mumm JS, Ackerley DF. A metagenomic library cloning strategy that promotes high-level expression of captured genes to enable efficient functional screening. Cell Chem Biol 2023; 30:1680-1691.e6. [PMID: 37898120 PMCID: PMC10842177 DOI: 10.1016/j.chembiol.2023.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 06/17/2023] [Accepted: 10/02/2023] [Indexed: 10/30/2023]
Abstract
Functional screening of environmental DNA (eDNA) libraries is a potentially powerful approach to discover enzymatic "unknown unknowns", but is usually heavily biased toward the tiny subset of genes preferentially transcribed and translated by the screening strain. We have overcome this by preparing an eDNA library via partial digest with restriction enzyme FatI (cuts CATG), causing a substantial proportion of ATG start codons to be precisely aligned with strong plasmid-encoded promoter and ribosome-binding sequences. Whereas we were unable to select nitroreductases from standard metagenome libraries, our FatI strategy yielded 21 nitroreductases spanning eight different enzyme families, each conferring resistance to the nitro-antibiotic niclosamide and sensitivity to the nitro-prodrug metronidazole. We showed expression could be improved by co-expressing rare tRNAs and encoded proteins purified directly using an embedded His6-tag. In a transgenic zebrafish model of metronidazole-mediated targeted cell ablation, our lead MhqN-family nitroreductase proved ∼5-fold more effective than the canonical nitroreductase NfsB.
Collapse
Affiliation(s)
- Michelle H Rich
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Abigail V Sharrock
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Timothy S Mulligan
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Frazer Matthews
- Department of Genetic Medicine, McKusick-Nathans Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Alistair S Brown
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Hannah R Lee-Harwood
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Elsie M Williams
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Janine N Copp
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Rory F Little
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Jenni J B Francis
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Claire N Horvat
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Luke J Stevenson
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Jeremy G Owen
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Meera T Saxena
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Jeff S Mumm
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; Department of Genetic Medicine, McKusick-Nathans Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; Center for Nanomedicine, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - David F Ackerley
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, Victoria University of Wellington, Wellington 6012, New Zealand.
| |
Collapse
|