Comparative proteomic studies in Rhodospirillum rubrum grown under different nitrogen conditions.
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, CO(2) fixation, and poly-beta-hydroxybutyrate metabolism) and amino acid metabolism. The key enzymes RuBisCO and alpha-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 p I values in response to the nitrogen source used.
Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, Sweden.
Tiago T
TT
Selao
Stefan
S
Nordlund
Agneta
A
Norén
D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis; D000596:Amino Acids / Q000378:metabolism; D000693:Anaerobiosis; D001426:Bacterial Proteins / Q000096:biosynthesis*; D002244:Carbon / Q000378:metabolism; D003470:Culture Media; D015180:Electrophoresis, Gel, Two-Dimensional; D066298:In Vitro Techniques; D009584:Nitrogen / Q000378:metabolism*; D040901:Proteomics; D012247:Rhodospirillum rubrum / Q000254:growth & development / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D018528:ATP-Binding Cassette Transporters; D000596:Amino Acids; D001426:Bacterial Proteins; D003470:Culture Media; D002244:Carbon; D009584:Nitrogen