Glutamine Synthetase Sensitivity to Oxidative Modification during Nutrient Starvation in Prochlorococcus marinus PCC 9511
Autor
Gómez-Baena, Guadalupe
Domínguez-Martín, María A.
Donaldson, Robert P.
García-Fernández, José Manuel
Díez Dapena, Jesús
Editor
Public Library of ScienceFecha
2015Materia
ImmunoprecipitationOxidation
Molecular mass
Oxidation-reduction reactions
Protein extraction
Antioxidants
Enzyme regulation
Glutamine
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Glutamine synthetase plays a key role in nitrogen metabolism, thus the fine regulation of
this enzyme in Prochlorococcus, which is especially important in the oligotrophic oceans
where this marine cyanobacterium thrives. In this work, we studied the metal-catalyzed oxidation
of glutamine synthetase in cultures of Prochlorococcus marinus strain PCC 9511
subjected to nutrient limitation. Nitrogen deprivation caused glutamine synthetase to be
more sensitive to metal-catalyzed oxidation (a 36% increase compared to control, non
starved samples). Nutrient starvation induced also a clear increase (three-fold in the case of
nitrogen) in the concentration of carbonyl derivatives in cell extracts, which was also higher
(22%) upon addition of the inhibitor of electron transport, DCMU, to cultures. Our results
indicate that nutrient limitations, representative of the natural conditions in the Prochlorococcus
habitat, affect the response of glutamine synthetase to oxidative inactivating systems.
Implications of these results on the regulation of glutamine synthetase by oxidative
alteration prior to degradation of the enzyme in Prochlorococcus are discussed.