Functional Studies of Thioredoxin Reductase in C.elegans.

Abstract

Thioredoxin reductases (trxr) are enzymes belonging to the flavoprotein family of pyridine nucleotide-disulphide oxidoreductases. Members of this family are homodimeric proteins in which each monomer includes an FAD prosthetic group, an NADPH binding site and an active site containing a redox-active disulphide. Electrons are transferred from NADPH via FAD to the active-site disulphide of trxr. This system has been conserved from bacteria to human. Previously the substrate of thioredoxin reductase, thioredoxin (trx-1), has been found that it is expressed in head neurons and intestine. Knockout mutants of trx-1, have been found to show shorter life span than that of wild type, indicating the reducing functions of thioredoxin system towards longevity. RNAi silencing of trx-1 showed less fat deposit in worm. We started to study the function of thioredoxin reductase. There are two thioredoxin reductases in C. elegans, trxr-1 and trxr-2. The trxr-1 is predicted to localize in cytoplasm, and it is the only selenocystein containing protein in C. elegans. The trxr-2 appeared to localize in mitochondria. They both are also expressed in intestine. Functional characterization of these two genes will be discussed.