doi:10.1038/nindia.2015.99 Published online 29 July 2015
Researchers have identified a protein that directly inhibits the activity of topoisomerase IV (topo IV), a complex that aids the segregation of chromosomes in the early stages of the cell cycle in the aquatic bacterium Caulobacter crescentus1. This finding throws new light on how bacterial pathogens regulate their cell cycles and provides important insights on the interactions between parasites and their hosts.
Previous studies had shown that chromosome segregation predominantly occurs in the late stages of bacterial cell cycle, but little work had been done to investigate chromosome segregation in the early stages of the bacterial cell cycle.
The researchers identified NstA, a cell-cycle-dependent regulator protein in C. crescentus, and found that it disrupted the activity of topo IV during the early stages of the cell cycle.
The scientists discovered that NstA stopped the function of topo IV by directly binding to a specific subunit of the topo IV complex. They also found that the intracellular oxidation–reduction (redox) state regulates the activity and abundance of NstA.
The researchers consider that dynamic intracellular redox may have more far-reaching implications for the cell cycle and bacterial pathogenesis.
1. Narayanan, S. A cell cycle-controlled redox switch regulates the topoisomerase IV activity. Genes & Dev. 29, 1175–1187 (2015)