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DNA Bacteriophages01:26

DNA Bacteriophages

Bacteriophages, or phages, are viruses that specifically infect bacteria, utilizing their genetic material to hijack host cellular machinery for replication. DNA bacteriophages employ single-stranded DNA (ssDNA) or double-stranded DNA (dsDNA) genomes. These phages exhibit diverse replication strategies and host interactions, influencing their ecological roles and applications in biotechnology and medicine.ssDNA BacteriophagesssDNA phages, with their small genomes, utilize unique strategies to...
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Following Cell-fate in E. coli After Infection by Phage Lambda
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Deciphering the function of lactococcal phage ul36 Sak domains.

Erika Scaltriti1, Sylvain Moineau, Hélène Launay

  • 1Architecture et Fonction des Macromolécules Biologiques, UMR 6098 CNRS and Universités d'Aix-Marseille I & II, Campus de Luminy, case 932, 13288 Marseille Cedex 09, France.

Journal of Structural Biology
|December 29, 2009
PubMed
Summary

The N-terminal domain of Sak, a phage protein, is crucial for DNA binding and annealing, essential for repairing phage DNA. The C-terminal domain does not bind DNA but may interact with other proteins.

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Following Cell-fate in E. coli After Infection by Phage Lambda
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Published on: October 14, 2011

Phage Phenomics: Physiological Approaches to Characterize Novel Viral Proteins
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Isolation and Genome Analysis of Single Virions using 'Single Virus Genomics'
08:31

Isolation and Genome Analysis of Single Virions using 'Single Virus Genomics'

Published on: May 26, 2013

Area of Science:

  • Molecular Biology
  • Virology
  • Dairy Microbiology

Background:

  • Bacteriophages cause significant losses in the dairy industry by infecting Lactococcus lactis starter cultures.
  • Single-strand annealing proteins (SSAPs), like Sak from phage ul36, are found in lactococcal phages and are homologs of human RAD52 involved in DNA repair.
  • Understanding Sak's function is key to mitigating phage-induced fermentation failures.

Purpose of the Study:

  • To elucidate the functional characteristics of the N- and C-terminal domains of the lactococcal phage protein Sak.
  • To compare the DNA binding and oligomerization properties of full-length Sak with its individual domains.
  • To investigate the role of Sak domains in DNA annealing and RecA strand exchange.

Main Methods:

  • High-Performance Liquid Chromatography Size Exclusion Chromatography (HPLC-SEC) to assess oligomerization.
  • Atomic Force Microscopy (AFM) and Surface Plasmon Resonance (SPR) to evaluate DNA binding affinities.
  • In vitro assays for single-strand annealing and RecA strand exchange stimulation.

Main Results:

  • The N-terminal domain (1-171) of Sak is essential and sufficient for DNA binding and oligomerization.
  • The C-terminal domain (172-252) does not exhibit DNA binding or oligomerization capabilities.
  • Only the N-terminal domain demonstrated single-strand annealing activity; neither domain stimulated RecA strand exchange.

Conclusions:

  • The N-terminus of Sak plays a primary role in DNA binding and annealing, crucial for phage replication and survival.
  • The C-terminus of Sak may be involved in protein-protein interactions, potentially with other phage or host factors.
  • These findings provide insights into phage-host interactions and potential targets for controlling phage infections in dairy fermentations.