Characterisation of the interaction of the cytoskeleton protein BacM and the Ras GTPase MglA of Myxococcus xanthus

MglA is the master regulator of A- and S-motility, and one of three RasGTPases, MXAN_1925 (MglA), MXAN_6703 (SofG), and MXAN_2495 of the soil bacterium Myxococcus xanthus. Besides motility, MglA plays key roles in cell division, polarity, fruiting body formation, and sporulation. Recent research has revealed that MglA and SofG specifically interact with bactofilin . Various bacterial and eukaryotic MglA homologues were used to test their ability to restore motility, colony expansion, fruiting body formation, and sporulation in mglA. With the exception of the 99% identical MglAstigm from the closely related myxobacterium S. aurantiaca, no other tested pro- or eukaryotic homologue, including mutated versions, was able to complement mglA. Importantly, in contrast to an earlier report, Sar1 from yeast was unable to rescue fruiting body spore formation, but instead formed glycerol spores upon starvation. Finally, mutated MglA was unsuccessfully used to detect potential post�translational modifications, indicating that other methods such as mass spectrometry may have to be employed in the future.