An adenine/thymidine-rich region is integral to RepL-mediated DNA replication

Area of Science:

• Molecular Biology
• Virology
• Genetics

Background:

• Bacteriophage P1 lytic replication depends on RepL expression and the lytic origin of replication (oriL).
• The precise location and function of P1 oriL within the repL gene, and the mechanisms of RepL-mediated DNA replication, remain incompletely understood.

Purpose of the Study:

• To investigate the role of specific sequences within the bacteriophage P1 repL gene in RepL-mediated DNA replication.
• To identify the functional elements of the lytic origin of replication (oriL) and their contribution to signal amplification.

Main Methods:

• Utilized reporter plasmids (GFP and RFP) to assess RepL-mediated DNA replication.
• Introduced synonymous base substitutions and mutations in the repL gene sequence, focusing on the AT2 region and identified binding sites (IHF, DnaA).
• Assessed the impact of truncated repL sequences and non-coding repL constructs (nc-repL) on replication and biosensor output.

Main Results:

• Synonymous base substitutions in the AT2 region of repL significantly inhibited RepL-mediated signal amplification.
• Mutations in IHF and DnaA binding sites did not substantially affect RepL-mediated signal amplification.
• A truncated repL sequence containing the AT2 region supported RepL-mediated signal amplification in trans, confirming AT2's role in replication.
• RepL constructs, including nc-repL, successfully amplified the output of an arsenic biosensor, with varying amplification levels observed upon AT2 region mutations.

Conclusions:

• The AT2 region within the repL gene is a critical component of the P1 lytic origin of replication (oriL).
• RepL-mediated DNA replication mechanisms are significantly influenced by the AT2 sequence.
• RepL constructs offer a promising strategy for amplifying and modulating the output of genetic biosensors, with potential applications in synthetic biology.