The miniF plasmid C protein: sequence, purification and DNA binding

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• The miniF C protein (pifC) plays a dual role in plasmid maintenance.
• It acts as a transcriptional repressor for its own gene via the pif operator (pifO).
• It is also essential for replication initiation at the miniF primary origin (ori-1).

Purpose of the Study:

• To determine the nucleotide sequence of the C gene.
• To express and purify the C protein.
• To investigate the DNA-binding properties of the C protein.

Main Methods:

• Nucleotide sequencing of the C gene.
• Gene insertion into an expression vector (Ptrp control).
• High-level protein expression and purification.
• Preliminary DNA-binding assays.

Main Results:

• The nucleotide sequence of the C gene was determined.
• High-level expression and purification of the C protein were achieved.
• The C protein demonstrated strong binding to the pifO sequence.
• Weak binding of the C protein to sequences within the ori-1 region was observed.

Conclusions:

• The C protein's DNA-binding properties support its role in transcriptional repression of its own gene.
• The observed weak binding to ori-1 suggests a potential regulatory role in miniF replication initiation.
• Further studies are warranted to fully elucidate the C protein's function in plasmid replication.