Bacteriophages take over host resources primarily via the activity of proteins expressed early in infection. One of these proteins, produced by the Escherichia coli phage T7, is gene product (Gp) 0.4. Here we show that Gp0.4 is a direct inhibitor of the E. coli division protein FtsZ. A chemically synthesized Gp0.4 binds to purified FtsZ and directly inhibits its assembly in vitro. Consequently, expression of Gp0.4 in vivo is lethal to E. coli and results in bacteria that are morphologically elongated. We further show that this inhibition of cell division by Gp0.4 enhances the bacteriophage's competitive ability. This division-inhibition is thus a fascinating example of a novel strategy in bacteriophages to maximize utilization of their hosts' cell resources.
