SSV1-encoded site-specific recombination system in Sulfolobus shibatae

Area of Science:

• Microbiology
• Molecular Biology
• Virology

Background:

• Site-specific recombination is crucial for viral genome integration and maintenance.
• Understanding archaeal virus-host interactions is essential for molecular biology.
• The Sulfolobus shibatae virus SSV1 is a model for archaeal viruses.

Purpose of the Study:

• To investigate the existence and mechanism of a conservative site-specific recombination system in Archaea.
• To characterize the SSV1 integrase enzyme and its role in viral DNA integration.
• To identify the DNA regions essential for SSV1 integration into the host chromosome.

Main Methods:

• Expressed the putative integrase (int) gene of SSV1 in Escherichia coli.
• Performed in vitro recombination assays using linear and supercoiled DNA substrates with viral (attP) and chromosomal (attA) attachment sites.
• Analyzed the role of the common attachment core and flanking sequences in recombination efficiency.

Main Results:

• Demonstrated in vitro integrative recombination of SSV1 DNA with the host chromosome, catalyzed by the SSV1 integrase.
• The purified SSV1 integrase protein efficiently recombined linear DNA substrates containing attA and attP sites.
• A conserved 44 bp core region within attachment sites was sufficient for recombination, with flanking sequences modulating efficiency.

Conclusions:

• Evidence supports a conservative site-specific recombination system in Archaea, mediated by SSV1 integrase.
• The SSV1 recombination system exhibits unique features distinguishing it from other known systems.
• This system provides a valuable model for studying viral genome-host chromosome interactions and the evolution of recombination machinery.