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Feiss M, Young R, Ramsey J, Adhya S, Georgopoulos C, Hendrix RW, Hatfull GF, Gilcrease EB, Casjens SR. Hybrid Vigor: Importance of Hybrid λ Phages in Early Insights in Molecular Biology. Microbiol Mol Biol Rev 2022; 86:e0012421. [PMID: 36165780 PMCID: PMC9799177 DOI: 10.1128/mmbr.00124-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Laboratory-generated hybrids between phage λ and related phages played a seminal role in establishment of the λ model system, which, in turn, served to develop many of the foundational concepts of molecular biology, including gene structure and control. Important λ hybrids with phages 21 and 434 were the earliest of such phages. To understand the biology of these hybrids in full detail, we determined the complete genome sequences of phages 21 and 434. Although both genomes are canonical members of the λ-like phage family, they both carry unsuspected bacterial virulence gene types not previously described in this group of phages. In addition, we determined the sequences of the hybrid phages λ imm21, λ imm434, and λ h434 imm21. These sequences show that the replacements of λ DNA by nonhomologous segments of 21 or 434 DNA occurred through homologous recombination in adjacent sequences that are nearly identical in the parental phages. These five genome sequences correct a number of errors in published sequence fragments of the 21 and 434 genomes, and they point out nine nucleotide differences from Sanger's original λ sequence that are likely present in most extant λ strains in laboratory use today. We discuss the historical importance of these hybrid phages in the development of fundamental tenets of molecular biology and in some of the earliest gene cloning vectors. The 434 and 21 genomes reinforce the conclusion that the genomes of essentially all natural λ-like phages are mosaics of sequence modules from a pool of exchangeable segments.
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Affiliation(s)
- Michael Feiss
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Ryland Young
- Center for Phage Technology, Texas A&M AgriLife Research, College Station, Texas, USA
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Jolene Ramsey
- Center for Phage Technology, Texas A&M AgriLife Research, College Station, Texas, USA
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Sankar Adhya
- Laboratory of Molecular Biology, Center for Cancer Research, The National Cancer Institute, Bethesda, Maryland, USA
| | - Costa Georgopoulos
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Roger W. Hendrix
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Pittsburgh Bacteriophage Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Graham F. Hatfull
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Pittsburgh Bacteriophage Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Eddie B. Gilcrease
- Department of Civil and Environmental Engineering, University of Utah, Salt Lake City, Utah, USA
| | - Sherwood R. Casjens
- Division of Microbiology and Immunology, Pathology Department, University of Utah School of Medicine, Salt Lake City, Utah, USA
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA
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