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 MglA(Bd) GTP-binding are conserved. Deletion of mglA(Bd) abolished prey-invasion, but not gliding, and reduced T4P formation. MglA(Bd) 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, RomR(Bd) 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.
Centre for Genetics and Genomics, School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom.
David S
DS
Milner
Centre for Genetics and Genomics, School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom.
Rob
R
Till
School of Biosciences, University of Birmingham, Birmingham, United Kingdom.
Ian
I
Cadby
School of Biosciences, University of Birmingham, Birmingham, United Kingdom.
Andrew L
AL
Lovering
Centre for Genetics and Genomics, School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom.
Sarah M
SM
Basford
Centre for Genetics and Genomics, School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom.
Emma B
EB
Saxon
School of Biosciences, University of Nottingham, Sutton Bonington, Nottinghamshire, United Kingdom.
Susan
S
Liddell
Bacterial Epidemiology and Antimicrobial Resistance Research Unit, Agricultural Research Service, United States Department of Agriculture, Athens, Georgia, United States of America.
Laura E
LE
Williams
Centre for Genetics and Genomics, School of Life Sciences, University of Nottingham, Medical School, Nottingham, United Kingdom.
R Elizabeth
RE
Sockett
D001426:Bacterial Proteins / Q000235:genetics*; D001501:Bdellovibrio / Q000235:genetics*; D002465:Cell Movement / Q000235:genetics; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000235:genetics; D020558:GTP Phosphohydrolases / Q000235:genetics*; D020690:GTPase-Activating Proteins / Q000235:genetics*; D016941:Myxococcus xanthus / Q000235:genetics*; D009876:Operon / Q000235:genetics; D018631:ras Proteins / Q000235:genetics*
D001426:Bacterial Proteins; D020690:GTPase-Activating Proteins; C071728:MglA protein, Myxococcus xanthus; C062025:bis(3',5')-cyclic diguanylic acid; D020558:GTP Phosphohydrolases; D018631:ras Proteins; D006152:Cyclic GMP