Isolation and characterization of Azospirillum brasilense loci that correct Rhizobium meliloti exoB and exoC mutations.
J Bacteriol
; 170(11): 5401-4, 1988 Nov.
Article
em En
| MEDLINE
| ID: mdl-3182731
The occurrence in Azospirillum brasilense of genes that code for exopolysaccharide (EPS) synthesis was investigated through complementation studies of Rhizobium meliloti Exo- mutants. These mutants are deficient in the synthesis of the major acidic EPS of Rhizobium species and form empty, non-nitrogen-fixing root nodules on alfalfa (J. A. Leigh, E. R. Signer, and G. C. Walker, Proc. Natl. Acad. Sci. USA 82:6231-6235, 1985). We demonstrated that the exoC mutation of R. meliloti could be corrected for EPS production by several cosmid clones of a clone bank of A. brasilense ATCC 29145. However, the EPS produced differed in structure from the wild-type R. meliloti EPS, and the symbiotic deficiency of the exoC mutation was not reversed by any of these cosmid clones. The exoB mutation could be corrected not only for EPS production but also for the ability to form nitrogen-fixing nodules on alfalfa by one particular cosmid clone of A. brasilense. Tn5 insertions in the cloned DNA were isolated and used to construct Azospirillum mutants with mutations in the corresponding loci by marker exchange. It was found that these mutants failed to produce the wild-type high-molecular-weight EPS, but instead produced EPSs of lower molecular weight.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Polissacarídeos Bacterianos
/
Rhizobium
/
Spirillum
/
Genes
/
Genes Bacterianos
/
Mutação
País/Região como assunto:
America do sul
/
Brasil
Idioma:
En
Revista:
J Bacteriol
Ano de publicação:
1988
Tipo de documento:
Article
País de afiliação:
Bélgica
País de publicação:
Estados Unidos