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A super-family of transcriptional activators regulates bacteriophage packaging and lysis in Gram-positive bacteria.

Quiles-Puchalt N, Tormo-Más MÁ, Campoy S, Toledo-Arana A, Monedero V, Lasa I, Novick RP, Christie GE, Penadés JR - Nucleic Acids Res. (2013)

Bottom Line: These regulators constitute a super-family of proteins, here named late transcriptional regulators (Ltr), which share common structural, biochemical and functional characteristics and are unique to this group of phages.To control expression of the late operon, the Ltr proteins bind to a DNA repeat region situated upstream of the terS gene, activating its transcription.This involves the C-terminal part of the Ltr proteins, which control specificity for the DNA repeat region.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biomedicina de Valencia (IBV-CSIC), 46010 Valencia, Spain, Centro de Investigación y Tecnología Animal, Instituto Valenciano de Investigaciones Agrarias (CITA-IVIA), Apdo. 187, 12.400 Segorbe, Castellón, Spain, Departamento de Ciencias Biomédicas, Universidad CEU Cardenal Herrera, 46113 Moncada, Valencia, Spain, Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain, Instituto de Agrobiotecnología, CSIC-Universidad Pública de Navarra, 31006 Pamplona, Navarra, Spain, Laboratorio de Bacterias Lacticas y Probioticos, Instituto de Agroquimica y Tecnologia de Alimentos-CSIC, 46980 Paterna, Valencia, Spain, Skirball Institute Program in Molecular Pathogenesis and Departments of Microbiology and Medicine, New York University Medical Center, 540 First Avenue, New York, NY 10016, USA, Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA 23298-0678, USA and Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, G12 8TA Glasgow, UK.

ABSTRACT
The propagation of bacteriophages and other mobile genetic elements requires exploitation of the phage mechanisms involved in virion assembly and DNA packaging. Here, we identified and characterized four different families of phage-encoded proteins that function as activators required for transcription of the late operons (morphogenetic and lysis genes) in a large group of phages infecting Gram-positive bacteria. These regulators constitute a super-family of proteins, here named late transcriptional regulators (Ltr), which share common structural, biochemical and functional characteristics and are unique to this group of phages. They are all small basic proteins, encoded by genes present at the end of the early gene cluster in their respective phage genomes and expressed under cI repressor control. To control expression of the late operon, the Ltr proteins bind to a DNA repeat region situated upstream of the terS gene, activating its transcription. This involves the C-terminal part of the Ltr proteins, which control specificity for the DNA repeat region. Finally, we show that the Ltr proteins are the only phage-encoded proteins required for the activation of the packaging and lysis modules. In summary, we provide evidence that phage packaging and lysis is a conserved mechanism in Siphoviridae infecting a wide variety of Gram-positive bacteria.

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Related in: MedlinePlus

Location of the genes controlled by the Ltr proteins. Partial genetic maps of ϕFL2A (Genbank accession number NC_013643) and ϕ55 (accession number AY954963), showing the location of the ltr genes and the genes under their control. Arrows indicate predicted ORFs, numbered as annotated. Grey arrows indicate the regulatory genes deleted in this study, whereas black arrows indicate genes for which expression was analysed by qRT-PCR.
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gkt508-F1: Location of the genes controlled by the Ltr proteins. Partial genetic maps of ϕFL2A (Genbank accession number NC_013643) and ϕ55 (accession number AY954963), showing the location of the ltr genes and the genes under their control. Arrows indicate predicted ORFs, numbered as annotated. Grey arrows indicate the regulatory genes deleted in this study, whereas black arrows indicate genes for which expression was analysed by qRT-PCR.

Mentions: In this work, we explored the hypothesis that most of the phages infecting the Gram-positive Firmicutes control packaging and lysis in a manner similar to that described for RinA. We have now identified five different families of phage-encoded regulators controlling phage-mediated late gene expression. Each family shares the size and charge characteristics previously found for the RinA proteins and a structurally similar C-terminal domain, as well as the location of the gene in the phage genome (Figure 1). These activators constitute a super-family of proteins that we have designated as for late transcriptional regulators (Ltr). Representatives of each family have been shown to control expression of phage-mediated packaging and lysis functions, which are required not only for phage growth but also for phage-mediated horizontal gene transfer.Figure 1.


A super-family of transcriptional activators regulates bacteriophage packaging and lysis in Gram-positive bacteria.

Quiles-Puchalt N, Tormo-Más MÁ, Campoy S, Toledo-Arana A, Monedero V, Lasa I, Novick RP, Christie GE, Penadés JR - Nucleic Acids Res. (2013)

Location of the genes controlled by the Ltr proteins. Partial genetic maps of ϕFL2A (Genbank accession number NC_013643) and ϕ55 (accession number AY954963), showing the location of the ltr genes and the genes under their control. Arrows indicate predicted ORFs, numbered as annotated. Grey arrows indicate the regulatory genes deleted in this study, whereas black arrows indicate genes for which expression was analysed by qRT-PCR.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3753634&req=5

gkt508-F1: Location of the genes controlled by the Ltr proteins. Partial genetic maps of ϕFL2A (Genbank accession number NC_013643) and ϕ55 (accession number AY954963), showing the location of the ltr genes and the genes under their control. Arrows indicate predicted ORFs, numbered as annotated. Grey arrows indicate the regulatory genes deleted in this study, whereas black arrows indicate genes for which expression was analysed by qRT-PCR.
Mentions: In this work, we explored the hypothesis that most of the phages infecting the Gram-positive Firmicutes control packaging and lysis in a manner similar to that described for RinA. We have now identified five different families of phage-encoded regulators controlling phage-mediated late gene expression. Each family shares the size and charge characteristics previously found for the RinA proteins and a structurally similar C-terminal domain, as well as the location of the gene in the phage genome (Figure 1). These activators constitute a super-family of proteins that we have designated as for late transcriptional regulators (Ltr). Representatives of each family have been shown to control expression of phage-mediated packaging and lysis functions, which are required not only for phage growth but also for phage-mediated horizontal gene transfer.Figure 1.

Bottom Line: These regulators constitute a super-family of proteins, here named late transcriptional regulators (Ltr), which share common structural, biochemical and functional characteristics and are unique to this group of phages.To control expression of the late operon, the Ltr proteins bind to a DNA repeat region situated upstream of the terS gene, activating its transcription.This involves the C-terminal part of the Ltr proteins, which control specificity for the DNA repeat region.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biomedicina de Valencia (IBV-CSIC), 46010 Valencia, Spain, Centro de Investigación y Tecnología Animal, Instituto Valenciano de Investigaciones Agrarias (CITA-IVIA), Apdo. 187, 12.400 Segorbe, Castellón, Spain, Departamento de Ciencias Biomédicas, Universidad CEU Cardenal Herrera, 46113 Moncada, Valencia, Spain, Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain, Instituto de Agrobiotecnología, CSIC-Universidad Pública de Navarra, 31006 Pamplona, Navarra, Spain, Laboratorio de Bacterias Lacticas y Probioticos, Instituto de Agroquimica y Tecnologia de Alimentos-CSIC, 46980 Paterna, Valencia, Spain, Skirball Institute Program in Molecular Pathogenesis and Departments of Microbiology and Medicine, New York University Medical Center, 540 First Avenue, New York, NY 10016, USA, Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA 23298-0678, USA and Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, G12 8TA Glasgow, UK.

ABSTRACT
The propagation of bacteriophages and other mobile genetic elements requires exploitation of the phage mechanisms involved in virion assembly and DNA packaging. Here, we identified and characterized four different families of phage-encoded proteins that function as activators required for transcription of the late operons (morphogenetic and lysis genes) in a large group of phages infecting Gram-positive bacteria. These regulators constitute a super-family of proteins, here named late transcriptional regulators (Ltr), which share common structural, biochemical and functional characteristics and are unique to this group of phages. They are all small basic proteins, encoded by genes present at the end of the early gene cluster in their respective phage genomes and expressed under cI repressor control. To control expression of the late operon, the Ltr proteins bind to a DNA repeat region situated upstream of the terS gene, activating its transcription. This involves the C-terminal part of the Ltr proteins, which control specificity for the DNA repeat region. Finally, we show that the Ltr proteins are the only phage-encoded proteins required for the activation of the packaging and lysis modules. In summary, we provide evidence that phage packaging and lysis is a conserved mechanism in Siphoviridae infecting a wide variety of Gram-positive bacteria.

Show MeSH
Related in: MedlinePlus