Ras GTPase-Like Protein MglA,a Controller of Bacterial Social-Motility in Myxobacteria,Has Evolved to Control Bacterial Predation by Bdellovibrio

Bdellovibrio bacteriovorus invade gram-negative bacteria in a predatory process requiring type iv pili (t4p) at a single invasive pole,and also glide on surfaces to locate prey. ras-like g-protein mgla,working with mglb and romr in the deltaproteobacterium myxococcus xanthus,regulates adventurous gliding and t4p-mediated social motility at both m. xanthus cell poles. our bioinformatic analyses suggested that the gtpase activating protein (gap)-encoding gene mglb was lost in bdellovibrio,but critical residues for mglabd gtp-binding are conserved. deletion of mglabd abolished prey-invasion,but not gliding,and reduced t4p formation. mglabd interacted with a previously uncharacterised tetratricopeptide repeat (tpr) domain protein bd2492,which we show localises at the single invasive pole and is required for predation. bd2492 and romr also interacted with cyclic-di-gmp-binding receptor cdga,required for rapid prey-invasion. bd2492,romrbd and cdga localize to the invasive pole and may facilitate mgla-docking. bd2492 was encoded from an operon encoding a tamab-like secretion system. the tama protein and romr were found,by gene deletion tests,to be essential for viability in both predatory and non-predatory modes. control proteins,which regulate bipolar t4p-mediated social motility in swarming groups of deltaproteobacteria,have adapted in evolution to regulate the anti-social process of unipolar prey-invasion in the lone-hunter bdellovibrio. thus gtp-binding proteins and cyclic-di-gmp inputs combine at a regulatory hub,turning on prey-invasion and allowing invasion and killing of bacterial pathogens and consequent predatory growth of bdellovibrio. © 2014.