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The dnaJ (hsp40) Locus in Rhizobium leguminosarum bv. phaseoli Is Required for the Establishment of an Effective Symbiosis with Phaseolus vulgaris

¹Département des Sols et de Génie Agroalimentaire, Faculté des Sciences de l'Agriculture et de l'Alimentation, Pavillon Charles-Eugène Marchand, Université Laval, Québec, Qc, Canada G1K 7P4; ²Centre de Recherche et de Développement sur les Sols et les Grandes Cultures, Agriculture et Agroalimentaire Canada, 2560 boulevard Hochelaga, Sainte-Foy, Qc, Canada G1V 2J3

P121R25 is a Tn5-induced mutant of the effective Rhizobium leguminosarum bv. phaseoli strain P121R that is unable to use glutamate as the sole carbon and nitrogen source and is defective in symbiotic nitrogen fixation. Enzymatic analysis showed that three enzymes implicated in glutamate metabolism (glutamate dehydrogenase, 2-oxoglutarate dehydrogenase, and glutamate synthase) were affected by this mutation. Sequencing of the chromosomal locus bordering the Tn5 in P121R25 indicated the presence of the dnaK and dnaJ genes in an arrangement similar to that described in R. leguminosarum bv. viciae (GenBank accession number Y14649). The mutation was located in the dnaJ (hsp40) gene.

Additional keywords: glutamate catabolism.