The symbiotic defect of Rhizobium meliloti exopolysaccharide mutants is suppressed by lpsZ+, a gene involved in lipopolysaccharide biosynthesis.
exo mutants of Rhizobium meliloti SU47, which fail to secrete acidic extracellular polysaccharide (EPS), induce Fix- nodules on alfalfa. However, mutants of R. meliloti Rm41 carrying the same exo lesions induce normal Fix+ nodules. We show that such induction is due to a gene from strain Rm41, which we call lpsZ+, that is missing in strain SU47. lpsZ+ does not restore EPS production but instead alters the composition and structure of lipopolysaccharide. In both SU47 and Rm41, either lpsZ+ or exo+ is sufficient for normal nodulation. This suggests that in R. meliloti EPS and lipopolysaccharide can perform the same function in nodule development.
Williams
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MN
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Hollingsworth
R I
RI
Klein
S
S
Signer
E R
ER
D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D005838:Genotype; D009154:Mutation; D010641:Phenotype; D010944:Plants / Q000382:microbiology; D010957:Plasmids; D011135:Polysaccharides, Bacterial / Q000235:genetics*; D012231:Rhizobium / Q000235:genetics* / Q000502:physiology; D013489:Suppression, Genetic; D013559:Symbiosis / Q000235:genetics*
D004251:DNA Transposable Elements; D011135:Polysaccharides, Bacterial