Binary reducing equivalent pathways using NADPH-thioredoxin reductase and ferredoxin-thioredoxin reductase in the cyanobacterium Synechocystis sp. strain PCC 6803.

Thioredoxin (Trx) is a small ubiquitous protein involved in the disulfide-dithiol exchange reaction occurring in cells and organelles. In vivo, Trx is reduced by Trx reductase using NADPH or photosynthetically produced reducing equivalents, and the reduced form Trx takes on the physiological functions. In the cyanobacterium Synechocystis sp. PCC6803, two Trx reductases, ferredoxin-Trx reductase (FTR) and NADPH-Trx reductase (NTR), and four typical Trx isoforms have been identified by genomic analysis. Based on analysis of the physiological features of the Trx reductase disruptants, we found that the NTR-Trx pathway is important for the antioxidant system, whereas the FTR-Trx pathway may play a more important role in the control of cell growth rate. In addition, by quantification of Trx abundance in the wild-type and the disruptant Synechocystis cells, we found that the gene product of slr0623, the homolog of m-type Trx in higher plants, is the most abundant Trx, and that accumulation of Trx isoforms occurs dependent on the expression of the other redox-related proteins. A study of the binary reducing equivalent pathways in cyanobacterial cells is reported here.

Electric-field-induced conductance switching in FeCo Prussian blue analogues.

FeCo Prussian blue analogues, which are known as typical molecule-based magnets, exhibited abrupt conductance switching by applying a high electric field as well as by varying the temperature. The current density versus electric field (J-E) curves of FeCo Prussian blue with Rb cations in interstitial sites shows so-called negative resistance effects at electric fields higher than the threshold voltage. This means that the FeCo Prussian blue analogues are multiproperty materials in the sense that their conducting, magnetic, and optical properties can be reversibly controlled by certain external stimuli.