Glutaredoxins (GRXs) are small oxidoreductases that use glutathione (GSH) as a cofactor.CC-Type GRXs which have active site motif of [CC××] are only founded in higher plants.It is puzzling that the oxidoreductase activities of all the CC-Type GRXs have not been detected so far.MICROSPORELESS1 (MIL1) gene is a small gene found in rice (Oryza sativa), which is considered to encode a CC-Type GRX.MIL1 knock-out rice does not produce microspores in anthers and therefore cannot carry out normal meiosis, but has normal female fertility.Compared to other GRX types, we found that several essential residues for GSH binding are absent in MIL1.Molecular dynamic simulations showed that the wide-type MIL1-GSH complex is very unstable, indicating that MIL1 cannot bind GSH or the binding is very weak, suggesting that MIL1 has no oxidoreductase activity.We further proposed several mutations on MIL1.Molecular dynamic simulations showed that 41 mutation (A to K) significantly improved the stability of MIL1-GSH complex and might help MIL1 recover the oxidoreductase activity.