A NOVEL NUCLEAR MEMBER OF THE THIOREDOXIN SUPERFAMILY

We describe the isolation and characterization of a cDNA encoding maiz e (Zea mays L.) nucleoredoxin (NRX), a novel nuclear protein that is a member of the thioredoxin (TRX) superfamily. NRX is composed of three TRX-like modules arranged as direct repeats of the classic TRX domain . The first and third modules contain the amino acid sequence WCPPC, w hich indicates the potential for TRX oxidoreductase activity, and insu lin reduction assays indicate that at least the third module possesses TRX enzymatic activity. The carboxy terminus of NRX is a non-TRX modu le that possesses C residues in the proper sequence context to form a Zn finger. Immunolocalization preferentially to the nucleus within dev eloping maize kernels suggests a potential for directed alteration of the reduction state of transcription factors as part of the events and pathways that regulate gene transcription.