A phage T4 in vitro packaging system for cloning long DNA molecules

Area of Science:

• Molecular Biology
• Genomics
• Recombinant DNA Technology

Background:

• Analysis of complex genomes requires methods for propagating large DNA inserts in Escherichia coli.
• Bacteriophage T4 in vitro DNA packaging offers a potential solution for cloning large DNA fragments.

Purpose of the Study:

• To evaluate the bacteriophage T4 in vitro DNA packaging system for its capacity to clone long foreign DNA fragments.
• To assess the efficiency of T4 packaging for non-T4 DNA and its utility in constructing genomic libraries.

Main Methods:

• Testing T4 in vitro packaging with foreign DNA (lambda imm434 and P1-pBR322 hybrids).
• Utilizing P1-pBR322 hybrid vectors with loxP sites for cloning Escherichia coli genomic DNA fragments.
• Packaging ligated DNA using the T4 system and transduction into E. coli expressing P1 recombinase for circularization.

Main Results:

• The T4 in vitro system efficiently packages foreign DNA, comparable to mature T4 DNA.
• Cloning of Escherichia coli genomic DNA fragments up to 122 kb was achieved using the T4 packaging system and P1 vectors.
• Obtained clones were maintained as single-copy plasmids controlled by the P1 plasmid replicon.

Conclusions:

• The bacteriophage T4 in vitro DNA packaging system is effective for cloning large DNA inserts.
• This method facilitates the construction of genomic libraries with large DNA fragments for complex genome analysis.