Genomic sequence of C1, the first streptococcal phage

Area of Science:

• Microbiology
• Virology
• Genomics

Background:

• The C(1) bacteriophage is historically significant, defining phage typing for group C streptococci classification.
• It is one of the earliest isolated bacteriophages, with its role in bacterial classification being well-established.

Purpose of the Study:

• To conduct a comprehensive analysis of the C(1) bacteriophage using modern techniques.
• To elucidate its genomic structure, protein functions, and evolutionary relationships within the Podoviridae family.

Main Methods:

• Electron microscopy for structural analysis.
• Protein profiling to identify viral components.
• Complete nucleotide sequencing for genomic characterization.
• Bioinformatic analysis to predict open reading frame functions.

Main Results:

• The C(1) phage genome is a 16,687-nucleotide double-stranded DNA molecule with inverted terminal repeats, characteristic of the Podoviridae family.
• Functions were assigned to 9 open reading frames, including key proteins like DNA polymerase, holin, lysin, and capsid proteins.
• An HNH endonuclease family intron was identified within the lysin gene, suggesting a splicing mechanism for enzyme production.
• Evidence suggests a protein-primed DNA replication mechanism, similar to phi29-like phages, with covalently attached terminal proteins.

Conclusions:

• The C(1) bacteriophage possesses unique genomic and proteomic features within the Podoviridae family.
• Its replication strategy may involve a protein-primed mechanism, distinct from many other phages.
• Comparative genomics indicates C(1) is an evolutionarily unique bacteriophage, despite its historical importance.