Originally published as Genetics Published Articles Ahead of Print on July 29, 2007.

Genetics, Vol. 177, 557-566, September 2007, Copyright © 2007
doi:10.1534/genetics.107.076182

Triple Mutants Uncover Three New Genes Required for Social Motility in Myxococcus xanthus

Philip Youderian^* and Patricia L. Hartzell^,1

^* Department of Biology, Texas A&M University, College Station, Texas 83843-3052 and Department of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Moscow, Idaho 83844-3052

¹ Corresponding author: 142 Life Science South, Molecular Biology and Biochemistry, University of Idaho, Moscow, ID 83844-3052.
E-mail: hartzell{at}uidaho.edu

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.

International Access Link

Online ISSN: 1943-2361  Print ISSN: 0016-6731
Copyright 2009 by the Genetics Society of America
phone: 412-268-1812   fax: 412-268-1813   email: genetics-gsa{at}andrew.cmu.edu