Disease relevance of exoB

• The gene in which these mutants are defective is functionally homologous to the exoB gene of Rhizobium meliloti [1].
• Isolation and characterization of Azospirillum brasilense loci that correct Rhizobium meliloti exoB and exoC mutations [2].
• The galE sequence of B. abortus 2308 is more similar to galE from other animal-inhabiting bacteria than it is to exoB from the Sinorhizobium legume symbionts [3].
• The UDP-glucose 4'-epimerase-encoding gene, galE or exoB, was isolated from Brucella abortus 2308 by complementation of an exoB mutant of Sinorhizobium meliloti [3].

High impact information on exoB

• The R. leguminosarum bv. viciae and R. meliloti exoB mutants fail to synthesize active UDP-glucose 4'-epimerase [1].
• The repeating unit of the residual amounts of EPS still made by the exoB mutants of R. leguminosarum bv. viciae lacks galactose and the substituents attached to it [1].
• This phenotype was shown to be dependent on the exoB and expE genes required for synthesis of exopolysaccharide II in R. meliloti but not to be dependent on genes required exclusively for the synthesis of the succinoglycan or exopolysaccharide I [4].
• Suppression of the Fix- phenotype of Rhizobium meliloti exoB mutants by lpsZ is correlated to a modified expression of the K polysaccharide [5].
• The replacement genes were contained on a cosmid which encoded the entire known R. meliloti exo gene cluster, with the exception of exoB [6].

Chemical compound and disease context of exoB

• Rhizobium leguminosarum exoB mutants are deficient in the synthesis of UDP-glucose 4'-epimerase [1].

Biological context of exoB

• 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 [2].
• The kinetics of nodule formation by these mutant strains, by an exoB mutant, and by mixed mutant inocula suggest that the gene products required for nodule invasion may also influence nodule meristem induction [7].
• We have cloned a chromosomal DNA fragment from the R. leguminosarum bv trifolii genome that contains an open reading frame of 981 bp showing 80% identity at the amino acid level to the UDP-glucose 4-epimerase of R. meliloti [8].

Associations of exoB with chemical compounds

• The exoB mutant had a spectrum of LPS species which differed from those of both the wild-type parental strain and the exoC mutant [9].
• Similar results were obtained in a study of Rm1021, a wild-type isolate that lacks the lpsZ gene: the introduction of lpsZ into Rm1021 exoB (Rm6903) both suppresses the Fix- phenotype and results in a modified expression of the K polysaccharide [5].
• One gene was found to be homologous to exoB, which encodes a UDP-galactose 4'-epimerase [10].

Other interactions of exoB

• RNA analysis suggests that the newly identified locus is transcribed in free-living cultures of ndvB and exoB strains, as well as in the parental R. meliloti strain [7].

References