ISSN:
1432-072X
Schlagwort(e):
Bradyrhizobium japonicum
;
Nitrate
;
Membrane-bound nitrate reductase
;
Nitrate reductase mutants
;
Microaerobiosis
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
Notizen:
Abstract Native PAGE of Triton x-100-solubilized membranes from Bradyrhizobium japonicum strain PJ17 grown microaerobically (2% O2, v/v) in defined nitrate-containing medium resolved two catalytically active nitrate reductase (NR) species with apparent molecular masses of 160 kDa (NRI) and 200 kDa (NRII). NRI and NRII were also found in membranes from cells of strain PJ17 that were first grown in defined medium with glutamate and further incubated microaerobically in the presence of 5 mmol/l KNO3. However, only NRI was detected in cell membranes of strain PJ17 when nitrate was omitted from the microaerobic incubation medium. Four mutants unable to grow at low O2 tension in the presence of nitrate were isolated after transposon Tn5 mutagenesis. Membranes from mutants GRF110 and GRF116 showed mainly NRI, while the other two mutants, GRF3 and GRF4, expressed mostly NRII. These results indicate that the ability of B. japonicum PJ17 to grow under microaerobic conditions depends upon the presence of two membrane-bound NR enzymes whose synthesis seem to be independently induced by microaerobiosis (NRI) or by both microaerobiosis and nitrate (NRII).
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00263777
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