Calcium sensing via EF-hand 4 enables thioredoxin activity in the sensor-responder protein calredoxin in the green alga Chlamydomonas reinhardtii.

ABSTRACT: Calcium (Ca²⁺) and redox signaling enable cells to quickly adapt to changing environments. The signaling protein calredoxin (CRX) from the green alga Chlamydomonas reinhardtii is a chloroplast-resident thioredoxin having Ca²⁺-dependent activity and harboring a unique combination of an EF-hand domain connected to a typical thioredoxin-fold. Using small-angle X-ray scattering (SAXS), FRET, and NMR techniques, we found that Ca²⁺-binding not only induces a conformational change in the EF-hand domain, but also in the thioredoxin domain, translating into the onset of thioredoxin redox activity. Functional analyses of CRX with genetically altered EF-hands revealed that EF-hand 4 is important for mediating the communication between the two domains. Moreover,

SUBMITTER: Charoenwattanasatien R 

PROVIDER: S-EPMC6952598 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature