Abstract
Filamentous cyanobacterium Anabaena (Nostoc) sp. PCC 7120 forms heterocyst for nitrogen fixation under nitrogen starved conditions. In order to understand the roles of thioredoxin (Trx) especially in the heterocyst cells, we examined the Trx-affinity chromatography method using the immobilized Anabaena Trx mutant, in which an internal cysteine at the active site was substituted with serine. The target proteins for thioredoxin in Anabaena were efficiently acquired from the vegetative cells and the heterocyst cells. The obtained proteins were separated by two-dimensional gel electrophoresis and analyzed by MALDI-TOF mass spectrometry. We have identified 38 proteins for Trx potential target proteins in the vegetative cells. In addition, we have identified several specific proteins including the nitrogenase in the soluble proteins of isolated heterocysts. Based on the obtained proteomics data, the role of thioredoxin is discussed.
