AtGRX4, an Arabidopsis chloroplastic monothiol glutaredoxin, is able to suppress yeast grx5 mutant phenotypes and respond to oxidative stress.

Arabidopsis monothiol glutaredoxin (Grx), AtGRX4, was targeted to chloroplasts/plastids and had high similarity to yeast Grx5. In yeast expression assays, AtGRX4 localized to the mitochondria and suppressed the sensitivity of grx5 cells to oxidants. In addition, AtGRX4 reduced iron accumulation and rescued the lysine auxotrophy of grx5 cells. In planta, AtGRX4 RNA transcripts accumulated in growing tissues. Furthermore, AtGRX4expression was altered under various stresses. Genetic analysis revealed that seedlings of atgrx4 mutants were sensitive to oxidants. Taken together, these results suggest that AtGRX4 may have important functions in plant growth and development under extreme environments.