Investigating Neisseria gonorrhoeae chromosomal replication dynamics

PROJECT SUMMARY Neisseria gonorrhoeae (Gc) causes one of the most common sexually transmitted infections. Increasing antimicrobial resistance is a major public health issue. Gc has more than one copy of its chromosome per cell, while a closely related commensal Neisseria has a single chromosomal copy. I have identified the putative origin or replication (oriC) and will determine the minimal oriC sequence and which conserved sequences are required for replication and growth. I will also determine whether oriC can drive the replication of an extrachromosomal episome. Additionally, I will determine whether DnaA protein levels are responsible for regulating chromosomal copy number. Finally, I will determine whether the oriC controls chromosomal copy number by swapping the oriC sequences between polyploid Gc and the commensal monoploid N. lactamica, and if they can, whether this alters ploidy status and other aspects of Gc physiology and genetics. This study will provide the first molecular characterization of the Gc oriC and the role of polyploidy in Gc genetics and physiology. Understanding the fundamental mechanisms of chromosome replication initiation and the maintenance of polyploidy status may reveal insights into mutation, antibiotic resistance generation, and diversification processes.