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Piya D, Nolan N, Moore ML, Ramirez Hernandez LA, Cress BF, Young R, Arkin AP, Mutalik VK. Systematic and scalable genome-wide essentiality mapping to identify nonessential genes in phages. PLoS Biol 2023; 21:e3002416. [PMID: 38048319 PMCID: PMC10695390 DOI: 10.1371/journal.pbio.3002416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 11/02/2023] [Indexed: 12/06/2023] Open
Abstract
Phages are one of the key ecological drivers of microbial community dynamics, function, and evolution. Despite their importance in bacterial ecology and evolutionary processes, phage genes are poorly characterized, hampering their usage in a variety of biotechnological applications. Methods to characterize such genes, even those critical to the phage life cycle, are labor intensive and are generally phage specific. Here, we develop a systematic gene essentiality mapping method scalable to new phage-host combinations that facilitate the identification of nonessential genes. As a proof of concept, we use an arrayed genome-wide CRISPR interference (CRISPRi) assay to map gene essentiality landscape in the canonical coliphages λ and P1. Results from a single panel of CRISPRi probes largely recapitulate the essential gene roster determined from decades of genetic analysis for lambda and provide new insights into essential and nonessential loci in P1. We present evidence of how CRISPRi polarity can lead to false positive gene essentiality assignments and recommend caution towards interpreting CRISPRi data on gene essentiality when applied to less studied phages. Finally, we show that we can engineer phages by inserting DNA barcodes into newly identified inessential regions, which will empower processes of identification, quantification, and tracking of phages in diverse applications.
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Affiliation(s)
- Denish Piya
- Innovative Genomics Institute, University of California-Berkeley, Berkeley, California, United States of America
| | - Nicholas Nolan
- Department of Bioengineering, University of California-Berkeley, Berkeley, California, United States of America
| | - Madeline L. Moore
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Luis A. Ramirez Hernandez
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Brady F. Cress
- Innovative Genomics Institute, University of California-Berkeley, Berkeley, California, United States of America
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, California, United States of America
| | - Ry Young
- Department of Biochemistry and Biophysics, Center for Phage Technology, Texas A&M University, College Station, Texas, United States of America
| | - Adam P. Arkin
- Innovative Genomics Institute, University of California-Berkeley, Berkeley, California, United States of America
- Department of Bioengineering, University of California-Berkeley, Berkeley, California, United States of America
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Vivek K. Mutalik
- Innovative Genomics Institute, University of California-Berkeley, Berkeley, California, United States of America
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
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