Identification of a nucleotide sequence conserved in Lactococcus lactis bacteriophages

Area of Science:

• Microbiology
• Molecular Biology
• Genomics

Background:

• Lactococcus lactis bacteriophages are significant in dairy fermentation.
• Genetic diversity exists among these bacteriophages, impacting their biological activity.
• Conserved genetic elements can provide insights into phage evolution and function.

Purpose of the Study:

• To identify and characterize a conserved genetic element in Lactococcus lactis bacteriophages.
• To determine the nucleotide sequence and analyze the genetic variation within this conserved region.
• To investigate the potential function of the protein encoded by this genetic element.

Main Methods:

• DNA sequencing of a 1.6-kb region from nine L. lactis bacteriophage isolates.
• Bioinformatic analysis to identify open reading frames (ORFs) and protein homology.
• Comparative analysis of nucleotide and amino acid sequences to assess genetic variation.

Main Results:

• A conserved DNA fragment, present in 95-99% of L. lactis bacteriophages, was identified.
• The fragment contains a large 1356-bp ORF encoding a 51-kDa protein.
• Minimal nucleotide sequence variation (five changes in 1536 bp) was observed, with two amino acid substitutions in the ORF that preserve protein charge.
• The encoded protein exhibits homology to yeast translation initiation factor and contains a potential zinc-binding domain.

Conclusions:

• The identified genetic element is highly conserved among L. lactis bacteriophages, suggesting functional importance.
• The encoded protein, with its homology to translation initiation factors and zinc-binding domain, likely plays a crucial role in phage biology.
• The limited genetic variation in this region indicates strong selective pressure, potentially related to essential phage functions.