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Isolation and characterization of an ndvB locus from Rhizobium fredii
Author(s) -
Bhagwat Arvind A.,
Tully Raymond E.,
Keister Donald L.
Publication year - 1992
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1992.tb01389.x
Subject(s) - biology , cosmid , bradyrhizobium japonicum , rhizobium , genetics , locus (genetics) , genomic library , gene , bradyrhizobium , mutant , rhizobiaceae , symbiosis , peptide sequence , bacteria
Summary A gene ( ndvB ) in Rhizobium meliloti that is essential for nodule development in Medicago sativa (alfalfa), specifies synthesis of a large membrane protein. This protein appears to be an intermediate in β‐1, 2‐glucan synthesis by the microsymbiont. Southern hybridization analysis showed strong homology between an ndvB (chvB) probe and genomic DNA of R. fredii but not from Bradyrhizobium japonicum. A cosmid clone containing the putative ndvB locus was isolated from a Rhizobium fredii gene library. The cosmid clone which complemented R. meliloti ndvB mutants for synthesis of β‐1, 2‐glucans and effective nodulation of alfalfa was mapped and subcloned. Fragment‐specific Tn5 mutagenesis followed by homologous recombination into the R. fredii genome indicated that the region was essential for β‐1, 2‐glucan synthesis and for formation of an effective symbiosis with Glycine max (soybean).