SE176:/MS02
From Metabolonote
Sample Set Information
| ID | TSE1334 |
|---|---|
| Title | Capillary electrophoresis-mass spectrometry reveals the distribution of carbon metabolites during nitrogen starvation in Synechocystis sp. PCC 6803. |
| Description | Nitrogen availability is one of the most important factors for the survival of cyanobacteria. Previous studies on Synechocystis revealed a contradictory situation with regard to metabolism during nitrogen starvation; that is, glycogen accumulated even though the expressions of sugar catabolic genes were widely upregulated. Here, we conducted transcript and metabolomic analyses using capillary electrophoresis-mass spectrometry on Synechocystis sp. PCC 6803 under nitrogen starvation. The levels of some tricarboxylic acid cycle intermediates (succinate, malate and fumarate) were greatly increased by nitrogen deprivation. Purine and pyrimidine nucleotides were markedly downregulated under nitrogen depletion. The levels of 19 amino acids changed under nitrogen deprivation, especially those of amino acids synthesized from pyruvate and phosphoenolpyruvate, which showed marked increases. Liquid chromatography-mass spectrometry analysis demonstrated that the amount of NADPH and the NADPH/NADH ratio decreased under nitrogen depletion. These data demonstrate that there are increases in not only glycogen but also in metabolites downstream of sugar catabolism in Synechocystis sp. PCC 6803 under nitrogen starvation, resolving the contradiction between glycogen accumulation and induction of sugar catabolic gene expression in this unicellular cyanobacterium. |
| Authors | Osanai, T., Oikawa, A., Shirai, T., Kuwahara, A., Iijima, H., Tanaka, K., Ikeuchi, M., Kondo, A., Saito, K. and Hirai, M.Y. |
| Reference | Environ Microbiol. 2014 Feb;16(2):512-24. doi: 10.1111/1462-2920.12170. |
| Comment |
Analytical Method Details Information
| ID | MS02 |
|---|---|
| Title | LC/MS/MS analysis |
| Instrument | LCMS‐8040 triple quadrupole LC/MS/MS spectrometer; Shimadzu |
| Instrument Type | |
| Ionization | ESI |
| Ion Mode | |
| Description | Equal amounts of cells (10 ml cell culture with A730 = 1.0) were harvested by rapid filtration, and metabolites were extracted using a previously described method (Soga, 2007; Yoshida et al., 2008), with modifications. Briefly, the harvested cells were immediately filtered, and then the intermediate metabolites were quenched and extracted in a 1.2 ml solvent mixture (CHCl3 : CH3OH : H2O, 2.5:2.5:1, v/v/v) containing 10 μg l−1 of D-(+)-camphor-10-sulfonic acid as an internal standard for semiquantitative analysis. After centrifugation at 13 000 r.p.m. (15 000 g) at 4°C for 5 min, 400 μl of the upper phase was transferred to a new tube and vacuum-dried. The intracellular metabolites were quantified by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LCMS-8040 triple quadrupole LC/MS/MS spectrometer; Shimadzu, Kyoto, Japan) as described previously (Luo et al., 2007). |
| Comment_of_details |
