GpsB interacts with FtsZ in multiple species and may serve as an accessory Z-ring anchor

Bacterial cytokinesis commences when a tubulin-like GTPase, FtsZ, forms a Z-ring to mark the division site. Synchronized movement of Z-ring filaments and peptidoglycan synthesis along the axis of division generates a division septum to separate the daughter cells. Thus, FtsZ needs to be linked to the peptidoglycan synthesis machinery. GpsB is a highly conserved protein among species of the Firmicutes phylum known to regulate peptidoglycan synthesis. Previously, we showed that Staphylococcus aureus GpsB directly binds to FtsZ by recognizing a signature sequence in its C-terminal tail (CTT) region. As the GpsB recognition sequence is also present in Bacillus subtilis, we speculated that GpsB may interact with FtsZ in this organism. Earlier reports revealed that disruption of gpsB and ftsA or gpsB and ezrA is deleterious. Given that both FtsA and EzrA also target the CTT of FtsZ for interaction, we hypothesized that in the absence of other FtsZ partners, GpsB-FtsZ interaction may become apparent. Our data confirm that is the case, and reveal that GpsB interacts with FtsZ in multiple species and stimulates the GTPase activity of the latter. Moreover, it appears that GpsB may serve as an accessory Z-ring anchor such as when FtsA, one of the main anchors, is absent.