Related Experiment Videos
The Myxococcus xanthus lipopolysaccharide O-antigen is required for social motility and multicellular development
1Department of Microbiology and Molecular Genetics, The University of Texas Medical School, Houston, TX 77030, USA.
Abstract:
The gliding bacterium Myxococcus xanthus aggregates to form spore-filled fruiting bodies when nutrients are limiting. Defective fruiting-body formation and sporulation result from mutations in the sasA locus, which encodes the wzm wzt wbgA (formerly rfbABC) lipopolysaccharide (LPS) O-antigen biosynthesis genes. Mutants carrying these same sasA mutations are defective in social motility and form small glossy colonies. We report here that the developmental and motility phenotypes of four mutants each containing different Tn5 insertions in LPS O-antigen biosynthesis genes are similar to those of the original sasA locus mutants. All of the LPS O-antigen mutants tested exhibited defective developmental aggregation and sporulated at only 0.02-15% of the wild-type level. In addition, all of the LPS O-antigen mutants were determined by genetic analyses to be wild type for adventurous motility and defective in social motility, indicating that the LPS O-antigen is necessary for normal development and social motility. The two previously identified cell-surface components required for social motility, type IV pili and the protein-associated polysaccharide material termed fibrils, were detected on the surfaces of all of the LPS O-antigen mutants. This indicates that LPS O-antigen is a third cell-surface component required for social motility.
Insights
Myxococcus xanthus requires lipopolysaccharide (LPS) O-antigen for social motility and development. Mutations in LPS O-antigen biosynthesis genes disrupt fruiting body formation and sporulation, identifying LPS as a third essential component for social motility.
Area of Science:
- Microbiology
- Bacterial Genetics
- Cellular Biology
Background:
- Myxococcus xanthus aggregates to form fruiting bodies under nutrient limitation.
- Mutations in the sasA locus, affecting lipopolysaccharide (LPS) O-antigen biosynthesis, impair fruiting body formation and sporulation.
- These sasA mutants also exhibit defects in social motility.
Purpose of the Study:
- To investigate the role of LPS O-antigen biosynthesis genes in Myxococcus xanthus development and motility.
- To determine if LPS O-antigen is essential for social motility.
- To identify the contribution of LPS O-antigen to Myxococcus xanthus cell surface characteristics.
Main Methods:
- Generating and characterizing Tn5 insertion mutants in LPS O-antigen biosynthesis genes.
- Assessing developmental phenotypes: fruiting body formation and sporulation.
- Evaluating motility phenotypes: social and adventurous motility.
- Analyzing cell surface components using genetic and microscopic techniques.
Main Results:
- Mutants with Tn5 insertions in LPS O-antigen biosynthesis genes displayed phenotypes similar to sasA mutants.
- All LPS O-antigen mutants showed defective developmental aggregation and significantly reduced sporulation.
- Genetic analyses confirmed these mutants were defective in social motility but retained adventurous motility.
- Type IV pili and fibrils, previously known motility components, were present on LPS O-antigen mutant surfaces.
Conclusions:
- Lipopolysaccharide (LPS) O-antigen is essential for normal development, including aggregation and sporulation, in Myxococcus xanthus.
- LPS O-antigen is a critical component required for social motility.
- LPS O-antigen represents a third distinct cell-surface component, alongside type IV pili and fibrils, necessary for Myxococcus xanthus social motility.