The Bradyrhizobium japonicum proline biosynthesis gene proC is essential for symbiosis.
Plant host-derived proline is proposed to serve as an energy source for rhizobia in the rhizosphere and in symbiotic root nodules. The Bradyrhizobium japonicum proC gene was isolated, and a proC mutant strain that behaved as a strict proline auxotroph in culture was constructed. The proC strain elicited undeveloped nodules on soybeans that lacked nitrogen fixation activity and plant hemoglobin. We conclude that the proC gene is essential for symbiosis and suggest that the mutant does not obtain an exogenous supply of proline in association with soybeans sufficient to satisfy its auxotrophy.
King
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Department of Biochemistry and Center for Microbial Pathogenesis, State University of New York at Buffalo, Buffalo, New York 14214, USA.
Hojnacki
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D
O'Brian
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MR
D000595:Amino Acid Sequence; D020369:Bradyrhizobium / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D009154:Mutation; D011392:Proline / Q000096:biosynthesis*; D011762:Pyrroline Carboxylate Reductases / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013025:Glycine max / Q000382:microbiology; D013559:Symbiosis; D000097502:delta-1-Pyrroline-5-Carboxylate Reductase
D011392:Proline; D011762:Pyrroline Carboxylate Reductases; D000097502:delta-1-Pyrroline-5-Carboxylate Reductase