Triple mutants uncover three new genes required for social motility in Myxococcus xanthus.
The bacterium Myxococcus xanthus glides over surfaces using two different locomotive mechanisms, called S (social) and A (adventurous) motility that enable cells to move both as groups and as individuals. Neither mechanism involves flagella. The functions of these two motors are coordinated by the activity of a small Ras-like protein, encoded by the mglA gene. The results of previous studies of a second-site suppressor of the mglA-8 missense mutation masK-815 indicate that MglA interacts with a protein tyrosine kinase, MasK, to control social motility. Sequence analysis of the sites of 12 independent insertions of the transposon magellan-4 that result in the loss of motility in an M. xanthus mglA-8 masK-815 double mutant shows that nine of these 12 insertions are in genes known to be required for S gliding motility. This result confirms that the masK-815 suppressor restores S but not A motility. Three of the 12 insertions define three new genes required for S motility and show that the attachment of heptose to the lipopolysaccharide inner core, an ortholog of the CheR methyltransferase, and a large protein with YD repeat motifs, are required for S motility. When these three insertions are backcrossed into an otherwise wild-type genetic background, their recombinants are found to have defects in S, but not, A motility. The spectrum of magellan-4 insertions that lead to the loss of S motility in the mglA-8 masK-815 double mutant background is different than that resulting from a previous mutant hunt starting with a different (A mutant) genetic background, suggesting that the number of genes required for S motility in M. xanthus is quite large.
Youderian
Philip
P
Department of Biology, Texas A&M University, College Station, Texas 83843-3052, USA.
Hartzell
Patricia L
PL
D001426:Bacterial Proteins / Q000235:genetics*; D005798:Genes, Bacterial; D006539:Heptoses / Q000378:metabolism; D008050:Lipid A / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008780:Methyltransferases / Q000378:metabolism; D008969:Molecular Sequence Data; D009068:Movement; D009154:Mutation / Q000235:genetics*; D016941:Myxococcus xanthus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D010641:Phenotype; D011995:Recombination, Genetic
D001426:Bacterial Proteins; D006539:Heptoses; D008050:Lipid A; D008070:Lipopolysaccharides; C071728:MglA protein, Myxococcus xanthus; D008780:Methyltransferases