Rhizobium phaseoli cytochrome c-deficient mutant induces empty nodules on Phaseolus vulgaris L. |
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Authors: | Mario Soberón Germán R Aguilar Federico Sánchez |
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Institution: | Departamento de Biología Molecular de Plantas, Instituto de Biotecnologia, Universidad Nacional Autonoma de México, Apartado Postal 510-3, Curnavaca Morelos 62271, México. |
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Abstract: | A Rhizobium phaseoli cytochrome mutant, unable to oxidize N,N,N′,N′ -tetramethyl-p-phenylend(amine (TMPD), was isolated after Mu-dl (Kan lac) mutagenesis of the wild-type strain CE-3. Mutant strain CFN4202 had sixfold less haem-c but similar levels of b type, o and aa3 cytochromes than the wild-type strain. CFN402 strain also showed reduced NADH- and TMPD-oxidase activity than the wild-type strain. Succinate-oxidase activities were very similar. Western blot experiments, using antiserum against bovine c1 and c cytochromes, revealed that both proteins were present in CFN4202 membranes, suggesting a defect of haem binding to cytochrome c. Nodules formed by this strain in Phaseolus vulgaris did not contain bacteroids. These data suggest that the cytochrome c-aa3 chain or some other respiratory chain, containing c-type cytochromes in R. phaseoli, is essential for bacterial division during the early steps of the symbiotic interaction with the legume-host. |
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