Ferredoxin-dependent glutamate synthase: involvement in ammonium assimilation in Haloferax mediterranei

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Title: Ferredoxin-dependent glutamate synthase: involvement in ammonium assimilation in Haloferax mediterranei
Authors: Pire, Carmen | Martínez-Espinosa, Rosa María | Pérez Pomares, Francisco | Esclapez Espliego, Julia María | Bonete, María-José
Research Group/s: Biotecnología de Extremófilos (BIOTECEXTREM)
Center, Department or Service: Universidad de Alicante. Departamento de Agroquímica y Bioquímica
Keywords: Haloferax mediterranei | GS/GOGAT pathway | Glutamate synthase expression | Enrichment and characterization
Knowledge Area: Bioquímica y Biología Molecular
Issue Date: Jan-2014
Publisher: Springer Japan
Citation: Extremophiles. 2014, 18(1): 147-159. doi:10.1007/s00792-013-0606-9
Abstract: Glutamate synthase (GOGAT) is one of the two important enzymes involved in the ammonium assimilation pathway glutamine synthetase (GS)/GOGAT, which enables Hfx. mediterranei to thrive in media with low ammonium concentration or containing just nitrate as single nitrogen source. The gene coding for this enzyme, gltS, has been sequenced, analysed and compared with other GOGATs from different organisms from the three domains of life. According to its amino acid sequence, Hfx. mediterranei GOGAT displays high homology with those from other archaeal halophilic organisms and with the bacterial alpha-like subunit. Hfx. mediterranei GOGAT and GS expression was induced under conditions of ammonium restriction. The GOGAT protein was found to be a monomer with a molecular mass of 163.78 kDa, which is consistent with that estimated by gel filtration, 198 ± 30 kDa. The enzyme is highly ferredoxin dependent: activity was only observed with one of the two different 2Fe–2S ferredoxins chromatographically isolated from Hfx. mediterranei. The enzyme also displayed typical halophilic behaviour, being fully stable, and producing maximal activity, at salt concentrations from 3 to 4 M NaCl, pH 7.5 and a temperature of 50 °C.
Sponsor: This work was supported by project BIO2008-00082 from the Spanish Ministry of Science and Innovation (MICINN), which includes funding from the European Union ("FEDER").
URI: http://hdl.handle.net/10045/37355
ISSN: 1431-0651 (Print) | 1433-4909 (Online)
DOI: 10.1007/s00792-013-0606-9
Language: eng
Type: info:eu-repo/semantics/article
Rights: The original publication is available at www.springerlink.com
Peer Review: si
Publisher version: http://dx.doi.org/10.1007/s00792-013-0606-9
Appears in Collections:INV - BIOTECEXTREM - Artículos de Revistas
INV - AppBiochem - Artículos de Revistas

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