A second exopolysaccharide of Rhizobium meliloti strain SU47 that can function in root nodule invasion

Journal Article · Mon May 01 00:00:00 EDT 1989 · Proceedings of the National Academy of Sciences of the United States of America; (USA)

DOI:https://doi.org/10.1073/pnas.86.9.3055· OSTI ID:5354393

Zhan, Hangjun; Levery, S B; Lee, C C; Leigh, J A ^[1]

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1. Univ. of Washington, Seattle (USA)

Rhizobium meliloti strain SU47 produces the calcofluor-binding exopolysaccharide, succinoglycan, that is required for alfalfa root nodule invasion. Strains derived from R. meliloti SU47 secreted an acidic exopolysaccharide, EPSb, that replaced succinoglycan in nodule invasion. EPSb, which has not formerly been identified among the Rhizobiaceae, consisted of the repeating unit 4,6-O-(1-carboxyethylidene)-{alpha}-D-Galp1{yields}3(X-O-Ac)-{beta}-D-Glcp1{yields}3. EPSb synthesis occurred either in strains containing a mutation in a locus designated mucR or in strains with a recombinant cosmid pMuc. mucR mapped slightly counterclockwise from pyr49 on the chromosome, while pMuc contained genes mapping to the megaplasmid pRmeSU47b. In exoA, -F, and -H mutants, which are deficient in normal succinoglycan secretion and nodule invasion, a transposon Tn5 insertion in mucR or the presence of pMuc resulted in EPSb secretion and a restoration of nodule invasion on Medicago sativa and Melilotus alba. Mutants in exoB and exoC were incapable of succinoglycan and EPSb secretion as well as nodule invasion. A mutant that secreted succinoglycan but was incapable of EPSb secretion invaded nodules normally.

• DOE Contract Number: FG06-86ER13532
• OSTI ID: 5354393
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (USA), Vol. 86:9; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
GENE MUTATIONS
GENETIC MAPPING
POLYSACCHARIDES
NUCLEAR MAGNETIC RESONANCE
RHIZOBIUM
MUTANTS
ALFALFA
BIOSYNTHESIS
GENE RECOMBINATION
NMR SPECTRA
ROOTS
SECRETION
BACTERIA
CARBOHYDRATES
LEGUMINOSAE
MAGNETIC RESONANCE
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MAPPING
MICROORGANISMS
MUTATIONS
ORGANIC COMPOUNDS
PLANTS
RESONANCE
SACCHARIDES
SPECTRA
SYNTHESIS
550200* - Biochemistry