<i>Mycobacterium</i>
            Phage Butters-Encoded Proteins Contribute to Host Defense against Viral Attack

Mageeney, Catherine M.; Mohammed, Hamidu T.; Dies, Marta; Anbari, Samira; Cudkevich, Netta; Chen, Yanyan; Buceta, Javier; Ware, Vassie C.

doi:10.1128/msystems.00534-20

Cited by 20 publications

(8 citation statements)

References 49 publications

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“…Homologs from phages Sbash, CarolAnn, and Butters confer a broad viral defense that mirrors the Rex exclusion behavior in λ (Gentile et al, 2019;Mageeney et al, 2020;Montgomery et al, 2019). These genes are organized in tandem in a single operon that is often directly adjacent to a CI-like repressor gene, raising the tantalizing possibility that other bacterial viruses also use these analogous systems to fine tune the balance between lysogeny and lytic growth.…”

Section: Lysogenic State Lytic Statementioning

confidence: 99%

Bacteriophage λ RexA and RexB functions assist the transition from lysogeny to lytic growth

Thomason

Schiltz

Court

et al. 2021

Molecular Microbiology

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λ is a temperate bacteriophage and thus can exist in either the lysogenic or lytic state (Echols, 1986;Oppenheim et al., 2005). The transition between these two states is mediated by two λ regulators: CI and Cro (Eisen et al., 1975;Ptashne & Hopkins, 1968). In the lysogenic state, the phage chromosome is integrated into that of its host Escherichia coli and is quiescent with its lytic functions repressed by the CI protein (Ptashne & Hopkins, 1968). In the repressed prophage, pairs of CI dimers bind cooperatively to operator sites O L1 and O L2 on the left and O R1 and O R2 on the right to repress the early P L and P R promoters (Figure 1), respectively, and, thereby, inhibit transcription of all the lytic genes downstream from those promoters (Johnson et al., 1979). Interaction between CI repressor molecules bound to the left and right operators results in topological looping of the intervening DNA, which contains the phage immunity region (Dodd et al., 2005); this looping enhances repression of P L and P R and stabilizes the lysogenic state. In a lysogen, the cI repressor gene is transcribed and

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Section: Lysogenic State Lytic Statementioning

confidence: 99%

Bacteriophage λ RexA and RexB functions assist the transition from lysogeny to lytic growth

Thomason

Schiltz

Court

et al. 2021

Molecular Microbiology

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“…Soils are intrinsically diverse partially due to their wide compositional spectrum and spatial heterogeneity in terms of physicochemical properties 1 , supporting a high diversity of interacting microbes that are pivotal to ecosystem services including global C and N biogeochemical cycles 2 . Viruses are extremely abundant and diverse biological entities on earth, playing vital roles in affecting soil microbiota and functions 3,4 via regulating microbial community dynamics 5 , reprogramming host metabolism during infection 6,7 , and serving as vectors of horizontal gene transfer 3 . Viral metagenomics has greatly expanded the viral ecology of aquatic ecosystems 8,9 and mammalian guts 10,11 , knowledge about soil viruses lags behind.…”

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confidence: 99%

Response of soil viral communities to land use changes

Liao

Duan

et al. 2022

Nat Commun

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Soil viruses remain understudied when compared to virus found in aquatic ecosystems. Here, we investigate the ecological patterns of soil viral communities across various land use types encompassing forest, agricultural, and urban soil in Xiamen, China. We recovered 59,626 viral operational taxonomic units (vOTUs) via size-fractioned viromic approach with additional mitomycin C treatment to induce virus release from bacterial fraction. Our results show that viral communities are significantly different amongst the land use types considered. A microdiversity analysis indicates that selection act on soil vOTUs, resulting in disparities between land use associated viral communities. Soil pH is one of the major determinants of viral community structure, associated with changes of in-silico predicted host compositions of soil vOTUs. Habitat disturbance and variation of soil moisture potentially contribute to the dynamics of putative lysogenic vOTUs. These findings provide mechanistic understandings of the ecology and evolution of soil viral communities in changing environments.

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“…Previous genetic studies identified rex- like genes in the temperate Actinobacteriophages Sbash, CarolAnn, and Butters that function as exclusion systems and provide broad defense activity to prevent superinfection by other viruses (85–87). An extensive BLAST search of the Actinobacteriophage Database (36) revealed additional Rex homologs in phages DumpsterDude, Toast, Rubeelu, Blino, and PCoral7 ( Supplementary Figs.…”

Section: Resultsmentioning

confidence: 99%

The crystal structure of bacteriophage λ RexA provides novel insights into the DNA binding properties of Rex-like phage exclusion proteins

Adams,

Schiltz,

Sun

et al. 2023

Preprint

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RexA and RexB function as an exclusion system that prevents bacteriophage T4rII mutants from growing on E. coli lambda phage lysogens. Recent data established that RexA is a non-specific DNA binding protein that can act independently of RexB to bias the lambda bistable switch toward the lytic state, preventing conversion back to lysogeny. The molecular interactions underlying these activities are unknown, owing in part to a dearth of structural information. Here we present the 2.05-Angstrom crystal structure of the lambda RexA dimer, which reveals a two-domain architecture with unexpected structural homology to the recombination-associated protein RdgC. Modelling suggests that our structure adopts a closed conformation and would require significant domain rearrangements to facilitate DNA binding. Mutagenesis coupled with electromobility shift assays, limited proteolysis, and double electron-electron spin resonance spectroscopy support a DNA-dependent conformational change. In vivo phenotypes of RexA mutants suggest that DNA binding is not a strict requirement for phage exclusion but may directly contribute to modulation of the bistable switch. We further demonstrate that RexA homologs from other temperate phages also dimerize and bind DNA in vitro. Collectively, these findings advance our mechanistic understanding of Rex functions and provide new evolutionary insights into different aspects of phage biology.

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Mycobacterium Phage Butters-Encoded Proteins Contribute to Host Defense against Viral Attack

Cited by 20 publications

References 49 publications

Bacteriophage λ RexA and RexB functions assist the transition from lysogeny to lytic growth

Bacteriophage λ RexA and RexB functions assist the transition from lysogeny to lytic growth

Response of soil viral communities to land use changes

The crystal structure of bacteriophage λ RexA provides novel insights into the DNA binding properties of Rex-like phage exclusion proteins

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