The cos region of lactococcal bacteriophage øLC3

Abstract

The nucleotide sequence of the DNA regions flanking the cohesive end site of the temperate lactococcal bacteriophage øLC3 was determined. Four pairs of sequence repeats of 8 to 13 basepairs in length were revealed close to the cohesive ends. These repeats possibly represent signal sequences involved in phage DNA maturation and packaging. The start of an open reading frame was localized only 42 nucleotides from the left end of the øLC3 phage double-stranded region, implying that transcription probably proceeds across the cos site. Compilation of the characteristics of the DNA termini of bacteriophages with complementary cohesive DNA ends suggests that phages of Gram-negative bacteria generally carry 5′-protruding singlestrands whereas those of Gram-positive hosts carry 3′-protruding ends.

Key Words:

• bacteriophage øLC3
• cohesive ends
• cos
• direct repeats
• Lactococcus lactis
• nucleotide sequence