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GENETYCZNE ASPEKTY WIĄZANIA N2 BAKTERII
Z RODZAJU AZOSPIRILLUM
Maria J. Król1, Julita
Zielewicz-Dukowska2
1Zakład Mikrobiologii Rolniczej, IUNG, Osada Pałacowa, 24-100 Puławy,
2Zakład Mikrobiologii Środowiskowej, Instytut Mikrobiologii i Biotechnologii
UMCS w Lublinie, ul. Akademicka 19
Wpłynęło w listopadzie 2003
1. Wstęp. 2. Metabolizm wiązania azotu. 3. Pozyskiwanie energii. 4. Podsumowanie
Genetical aspects of nitrogen fixation by bacteria
Azospirillum species
Abstract: Biological nitrogen fixation is catalysed by the nitrogen enzyme complex, which includes dinitrogenase (MoFe protein,
nifDK gene products), containing the active site of dinitrogen reduction, and dinitrogenase reductase (Fe protein,
nifH gene product) supplies the reducing power to the dinitrogenase. Nitrogenase is subject to elaborate control at the trans-criptional and post-translational levels by the concentrations of intracellular nitrogen and oxygen. Nitrogenase activity is also regulated at a post-translational level by two mechanisms. One of the best understood post-transcriptional regulatory mechanisms is reversible ADP-ribosylation, which has been found in some phototrophs and the
Azospirillum genus. The dinitrogenase reductase ADP-ribosyltransferase/dinitrogenase reductase-activating glycohydrolase (DRAT/DRAG) systems, which involves reversible nitro-genase inactivation
via ADP ribosylation in response to micromolar concentrations of ammonia. DRAT and DRAG are encoded by the
draTG operon, which is not co-regulated with the nif genes but which is found near the
nifHDK operon in R. rubrum, A. lipofrum and
A. brasilense. Both DRAT and DRAG activities are regulated
in vivo, but the mechanisms for their regulation are
unknown.
1. Introduction. 2. Metabolism nitrogen fixation. 3. Energy
supply. 4. Summary
Słowa
kluczowe: Azospirillum, wiązanie azotu
Key words: Azospirillum, nitrogen fixation |
