Structure and Function of the Campylobacter jejuni Chromosome Replication Origin

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Campylobacter jejuni is a leading cause of bacterial foodborne illness globally.
• Understanding the cell cycle of C. jejuni is limited, hindering knowledge of its pathogenesis.

Purpose of the Study:

• To identify and characterize the origin of replication (oriC) in C. jejuni.
• To investigate the regulatory mechanisms of C. jejuni chromosome replication initiation.

Main Methods:

• Bioinformatic analysis to identify the probable oriC region.
• In vitro assays to study DnaA binding and DNA unwinding element (DUE) activity.
• Minichromosome replication assays to assess oriC function.

Main Results:

• The C. jejuni oriC is monopartite, located in the dnaA-dnaN intergenic region, containing DnaA boxes and a DUE.
• DnaA binding to DnaA boxes initiated DUE unwinding in vitro.
• Additional DnaA boxes within the dnaA gene were required for efficient minichromosome replication.

Conclusions:

• The C. jejuni oriC requires specific DnaA boxes, potentially including those within a coding region, for replication initiation.
• Cj1509, a response regulator, inhibits DnaA-mediated DUE unwinding in vitro, suggesting a regulatory role in C. jejuni chromosome replication.
• This study provides foundational insights into C. jejuni chromosome replication, essential for understanding its life cycle and virulence.