Exploring the Protein-Protein Interactions of Neisseria gonorrhoeae Cell Division Proteins FtsE, FtsX, FtsL and FtsB

Abstract

Cell division is a vital process coordinated by both cell division proteins and an expansive network of protein-protein interactions. A previous study examined the interactions amongst cell division proteins in Neisseria gonorrhoeae (N. gonorrhoeae), a non-model organism, and identified several unique protein-protein interactions that are not observed in the model organism Escherichia coli (E. coli). Studies of bacterial cell division are often performed in E. coli, but this previous study suggested that N. gonorrhoeae cell division may be distinct from E. coli cell division. However, this previous study of interactions amongst N. gonorrhoeae cell division proteins lacked information regarding the self-interactions of N. gonorrhoeae cell division proteins and the protein-protein interactions between cell division proteins FtsE, FtsX, FtsL, and FtsB, and the other gonococcal cell division proteins. My research investigated the interactions of these proteins using Bacterial-2-Hybrid (B2H) assays, GST pulldown assays, and affinity purification combined with mass spectrometry (AP-MS) experiments. My research detected nine protein-protein interactions (i.e., FtsE-FtsX, FtsE-FtsQ, FtsL-FtsX, FtsL-ZipA, FtsX-ZipA, FtsX-FtsK, FtsX-FtsW, FtsX-FtsN, and FtsB-FtsZ) and four self-interactions (i.e., self-interactions of FtsE, FtsW, FtsB, and FtsN). Only four of these 13 interactions are common interactions that are also observed in E. coli (i.e., FtsE-FtsX and the self-interactions of FtsE, FtsB, and FtsN), supporting the hypothesis that N. gonorrhoeae cell division proteins exhibit unique interactions. GST pulldown assays further examined the FtsE-FtsQ interaction; however, the interaction could not be confirmed. AP-MS experiments were used to examine potential interactions between N. gonorrhoeae FtsE and proteins in a N. gonorrhoeae whole cell lysate. These experiments identified over 300 possible proteins that may interact with FtsE, including the cell division proteins FtsI, FtsK, and FtsN. The Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database was also used to predict potential interactions between the proteins identified during AP-MS experiments. This analysis predicted the interactions observed between FtsE-FtsX and FtsB-FtsZ that were identified by B2H assays. My research provides new data regarding the interactions of FtsE, FtsX, FtsL, and FtsB with other cell division proteins in N. gonorrhoeae and indicates that N. gonorrhoeae has a distinct cell division interaction network.