A secondary attachment site for bacteriophage lambda in trpC of E. coli

Area of Science:

• Molecular Biology
• Genetics
• Microbiology

Background:

• Bacteriophage lambda integration into bacterial genomes is a well-studied process.
• Attachment sites are specific DNA sequences recognized by phage integrase.
• Understanding these sites is crucial for genetic engineering and phage biology.

Purpose of the Study:

• To determine the nucleotide sequence of a secondary lambda attachment site within the trpC gene.
• To compare this secondary site with the primary lambda attachment site.
• To confirm the presence of the attachment site sequence in the host genome.

Main Methods:

• Direct DNA sequencing of lambdatrp transducing phage DNA fragments.
• Sequence analysis of prophage attachment sites.
• Analysis of trpC messenger RNA (mRNA) spanning the attachment region.

Main Results:

• A 6-nucleotide homology was identified in the crossover region of the secondary attachment site.
• This 6-nucleotide sequence is a subset of the 15-nucleotide core sequence (GCTTTTTTATACTAA) of the primary lambda attachment site.
• The 6-nucleotide sequence was also found in the intact trpC genome at the attachment site.

Conclusions:

• A conserved 6-nucleotide sequence is involved in lambda phage integration at a secondary attachment site in trpC.
• This finding suggests a common mechanism for integration at both primary and secondary sites.
• The presence of this sequence in the trpC genome validates its role as an attachment site.