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Comparative proteomic studies in Rhodospirillum rubrum grown under different nitrogen conditions
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
2008 (Engelska)Ingår i: Journal of Proteome Research, ISSN 1535-3893, E-ISSN 1535-3907, Vol. 7, nr 8, s. 3267-3275Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Forty-four differentially expressed proteins have been identified in the photosynthetic diazotroph Rhodospirillum rubrum grown anaerobic and photoheterotrophically, with different nitrogen sources, using 2D-PAGE and MALDI-TOF, from gels containing an average of 679 ± 52 (in N+) and 619 ± 37 (in N−) protein spots for each gel. A higher level of expression was found under nitrogen-rich growth, for proteins involved in carbon metabolism (reductive tricarboxylic acid cycle, CO2 fixation, and poly-β-hydroxybutyrate metabolism) and amino acid metabolism. The key enzymes RuBisCO and α-ketoglutarate synthase were found to be present in higher amounts in nitrogen-rich conditions. Ntr and Nif regulated proteins, such as glutamine synthetase and nitrogenase, were, as expected, induced under nitrogen-fixing conditions and glutamate dehydrogenase was down regulated. A novel 2Fe-2S ferredoxin with unknown function was identified from nitrogen-fixing cultures. In addition to differential expression, two of the identified proteins revealed variable pI values in response to the nitrogen source used.

Ort, förlag, år, upplaga, sidor
2008. Vol. 7, nr 8, s. 3267-3275
Nyckelord [en]
Rhodospirillum rubrum, nitrogen fixation, comparative proteome, 2D-PAGE
Nationell ämneskategori
Medicinsk bioteknologi (med inriktning mot cellbiologi (inklusive stamcellsbiologi), molekylärbiologi, mikrobiologi, biokemi eller biofarmaci)
Forskningsämne
biokemi
Identifikatorer
URN: urn:nbn:se:su:diva-14839DOI: 10.1021/pr700771uISI: 000258200400017PubMedID: 18570453OAI: oai:DiVA.org:su-14839DiVA, id: diva2:181359
Tillgänglig från: 2008-11-05 Skapad: 2008-11-05 Senast uppdaterad: 2017-12-13Bibliografiskt granskad
Ingår i avhandling
1. Regulation of nitrogen fixation in Rhodospirillum rubrum: Through proteomics and beyond
Öppna denna publikation i ny flik eller fönster >>Regulation of nitrogen fixation in Rhodospirillum rubrum: Through proteomics and beyond
2010 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Adaptability is one of the reasons for the success of bacteria, allowing them to survive in conditions where no other organisms would be able to thrive. Nitrogen deficiency, for example, can be a limiting factor for the growth of micro-organisms, as this element is an essential part of almost all types of biomolecules. As such, some bacteria have evolved specific mechanisms to overcome nitrogen limitation. Nitrogen fixing bacteria, or diazotrophs, use a specific enzyme complex, nitrogenase, in order to harness this element from the enormous reservoir that is the Earth’s atmosphere. However, nitrogen fixation is a demanding process for the cells, requiring vast amounts of energy and tight regulation.

In this thesis we explore the mechanisms regulating nitrogen fixation in Rhodospirillum rubrum, a purple non-sulphur photosynthetic bacterium. Using proteomics tools, we show how the regulation of both the nitrogen and carbon fixation processes is interconnected, possibly in order to maintain the intracellular redox balance. Using a new detergent molecule, we also demonstrate how nitrogen availability affects the chromatophore membrane proteome.

Our studies have revealed the crucial role of the cellular pool of 2-oxoglutarate (2OG) for adequate signaling through the PII proteins and the effects resulting from artificially manipulating this metabolite’s concentration. In R. rubrum nitrogenase is also subjected to post-translational control (the “switch-off” effect) and this work shows for the first time that the enzyme modifying nitrogenase (Dinitrogenase Reductase ADP-ribsosyl Transferase or DRAT) forms a complex with the PII protein GlnB. This complex allows DRAT activation and its formation – and, therefore, DRAT activity – is regulated by binding of ADP:ATP and 2OG to GlnB.

Upon light withdrawal, nitrogenase activity anaerobically in the dark is also here demonstrated to be dependent on the activity of the pathway starting in pyruvate formate-lyase and we show how different nitrogen sources influence the switch-off response. This response can, in some conditions, be modified by addition of pyruvate and we have studied how this metabolite influences nitrogenase activity and switch-off regulation.

This study allows a better understanding of the underlying processes controlling the metabolic routes in R. rubrum and also provides new insights into regulation of enzyme activity, paving the road for the complete establishment of the mechanisms regulating nitrogenase switch-off.

Ort, förlag, år, upplaga, sidor
Stockholm: Department of Biochemistry and Biophysics, Stockholm University, 2010. s. 71
Nyckelord
Rhodospirillum rubrum, nitrogen fixation, redox balance, switch-off, DRAT
Nationell ämneskategori
Biokemi och molekylärbiologi
Forskningsämne
biokemi
Identifikatorer
urn:nbn:se:su:diva-42101 (URN)978-91-7447-125-0 (ISBN)
Disputation
2010-10-08, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (Engelska)
Opponent
Handledare
Anmärkning

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: In press. Paper 3: Submitted. Paper 4: Manuscript. Paper 5: Submitted.

Tillgänglig från: 2010-09-16 Skapad: 2010-08-16 Senast uppdaterad: 2012-10-03Bibliografiskt granskad

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Selao, Tiago T.Nordlund, StefanNorén, Agneta
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Institutionen för biokemi och biofysik
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Journal of Proteome Research
Medicinsk bioteknologi (med inriktning mot cellbiologi (inklusive stamcellsbiologi), molekylärbiologi, mikrobiologi, biokemi eller biofarmaci)

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