Thioredoxin targets are regulated in heterocysts of cyanobacterium Anabaena sp. PCC 7120 in a light-independent manner. (21st December 2019)

• Record Type: Journal Article
• Authors: Mihara, Shoko; Sugiura, Kazunori; Yoshida, Keisuke; Hisabori, Toru
• Editors: Griffiths, Howard
• Is Part Of: Journal of experimental botany. Volume 71:Number 6(2020)
• Page Start: 2018
• Page End: 2027
• Publication Date: 2019-12-21
• Subjects: Anabaena -- heterocyst -- nitrogen fixation -- oxidative pentose phosphate pathway -- photosynthesis -- redox regulation -- thioredoxin; Botany -- Periodicals; Botany, Experimental -- Periodicals; Plant physiology -- Periodicals; 580
• DOI: 10.1093/jxb/erz561
• Languages: English
• ISSNs: 0022-0957

Abstract

Abstract: In the nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120, glucose 6-phosphate dehydrogenase (G6PDH) plays an important role in producing the power for reducing nitrogenase under light conditions. Our previous study showed that thioredoxin suppresses G6PDH by reducing its activator protein OpcA, implying that G6PDH is inactivated under light conditions because thioredoxins are reduced by the photosynthetic electron transport system in cyanobacteria. To address how Anabaena sp. PCC 7120 maintains G6PDH activity even under light conditions when nitrogen fixation occurs, we investigated the redox regulation system in vegetative cells and specific nitrogen-fixing cells named heterocysts, individually. We found that thioredoxin target proteins were more oxidized in heterocysts than in vegetative cells under light conditions. Alterations in the redox regulation mechanism of heterocysts may affect the redox states of thioredoxin target proteins, including OpcA, so that G6PDH is activated in heterocysts even under light conditions. Abstract : In phototrophs, thioredoxin targets are generally reduced in a light-dependent manner. In contrast, thioredoxin targets in heterocysts of nitrogen-fixing cyanobacteria are regulated independently of light conditions.