RT Journal Article SR Electronic T1 MglA functions as a three-state GTPase to control movement reversals of Myxococcus xanthus JF bioRxiv FD Cold Spring Harbor Laboratory SP 577387 DO 10.1101/577387 A1 Galicia, Christian A1 Lhospice, Sébastien A1 Fernández Varela, Paloma A1 Trapani, Stefano A1 Zhang, Wenhua A1 Navaza, Jorge A1 Mignot, Tâm A1 Cherfils, Jacqueline YR 2019 UL http://biorxiv.org/content/early/2019/03/14/577387.abstract AB In Myxococcus xanthus, directed movement is controlled by inter-dependent pole-to-pole oscillations of the small GTPase MglA, its GAP MglB and the RomR protein. However, these proteins have strikingly different oscillatory regimes such that MglA is segregated from MglB and RomR at reversal activation. The molecular mechanism whereby information is exchanged between the lagging and leading poles resulting in MglA detachment from the leading pole during reversals has remained unknown. Here, we show that MglA has two GTP-bound forms, one of which is insensitive to MglB (MglA-GTP*) and is re-sensitized to MglB by a feedback mechanism operated by MglA-GDP. By identifying the region of MglB that is critical for its association to the lagging pole, we demonstrate that MglA-GTP* is functional in vivo. These data suggest that MglA-GDP acts as a soluble messenger to convert polar MglA-GTP* into a diffusible MglA-GTP species, explaining MglA re-localization to the opposite pole during reversals.