Dataset Information

Phosphines are ribonucleotide reductase reductants that act via C-terminal cysteines similar to thioredoxins and glutaredoxins.

ABSTRACT: Ribonucleotide reductases (RNRs) catalyze the formation of 2'-deoxyribonucleotides. Each polypeptide of the large subunit of eukaryotic RNRs contains two redox-active cysteine pairs, one in the active site and the other at the C-terminus. In each catalytic cycle, the active-site disulfide is reduced by the C-terminal cysteine pair, which in turn is reduced by thioredoxins or glutaredoxins. Dithiols such as DTT are used in RNR studies instead of the thioredoxin or glutaredoxin systems. DTT can directly reduce the disulfide in the active site and does not require the C-terminal cysteines for RNR activity. Here we demonstrate that the phosphines tris(2-carboxyethyl)phosphine (TCEP) and tris(3-hydroxypropyl)phosphine (THP) are efficient non-thiol RNR reductants, but in contrast to the dithiols DTT, bis(2-mercaptoethyl)sulfone (BMS), and (S)-(1,4-dithiobutyl)-2-amine (DTBA) they act specifically via the C-terminal disulfide in a manner similar to thioredoxin and glutaredoxin. The simultaneous use of phosphines and dithiols results in ~3-fold higher activity compared to what is achieved when either type of reductant is used alone. This surprising effect can be explained by the concerted action of dithiols on the active-site cysteines and phosphines on the C-terminal cysteines. As non-thiol and non-protein reductants, phosphines can be used to differentiate between the redox-active cysteine pairs in RNRs.

SUBMITTER: Domkin V

PROVIDER: S-EPMC4078304 | biostudies-literature | 2014 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Phosphines are ribonucleotide reductase reductants that act via C-terminal cysteines similar to thioredoxins and glutaredoxins.

Domkin Vladimir V Chabes Andrei A

Scientific reports 20140702

Ribonucleotide reductases (RNRs) catalyze the formation of 2'-deoxyribonucleotides. Each polypeptide of the large subunit of eukaryotic RNRs contains two redox-active cysteine pairs, one in the active site and the other at the C-terminus. In each catalytic cycle, the active-site disulfide is reduced by the C-terminal cysteine pair, which in turn is reduced by thioredoxins or glutaredoxins. Dithiols such as DTT are used in RNR studies instead of the thioredoxin or glutaredoxin systems. DTT can di ...[more]

PMID: 24986213

Similar Datasets

Project description:A coenzyme B12-dependent ribonucleotide reductase was purified from the archaebacterium Thermoplasma acidophila and partially sequenced. Using probes derived from the sequence, the corresponding gene was cloned, completely sequenced, and expressed in Escherichia coli. The deduced amino acid sequence shows that the catalytic domain of the B12-dependent enzyme from T. acidophila, some 400 amino acids, is related by common ancestry to the diferric tyrosine radical iron(III)-dependent ribonucleotide reductase from E. coli, yeast, mammalian viruses, and man. The critical cysteine residues in the catalytic domain that participate in the thiyl radical-dependent reaction have been conserved even though the cofactor that generates the radical is not. Evolutionary bridges created by the T. acidophila sequence and that of a B12-dependent reductase from Mycobacterium tuberculosis establish homology between the Fe-dependent enzymes and the catalytic domain of the Lactobacillus leichmannii B12-dependent enzyme as well. These bridges are confirmed by a predicted secondary structure for the Lactobacillus enzyme. Sequence similarities show that the N-terminal domain of the T. acidophila ribonucleotide reductase is also homologous to the anaerobic ribonucleotide reductase from E. coli, which uses neither B12 nor Fe cofactors. A predicted secondary structure of the N-terminal domain suggests that it is predominantly helical, as is the domain in the aerobic E. coli enzyme depending on Fe, extending the homologous family of proteins to include anaerobic ribonucleotide reductases, B12 ribonucleotide reductases, and Fe-dependent aerobic ribonucleotide reductases. A model for the evolution of the ribonucleotide reductase family is presented; in this model, the thiyl radical-based reaction mechanism is conserved, but the cofactor is chosen to best adapt the host organism to its environment. This analysis illustrates how secondary structure predictions can assist evolutionary analyses, each important in "post-genomic" biochemistry.

Dataset Information

Phosphines are ribonucleotide reductase reductants that act via C-terminal cysteines similar to thioredoxins and glutaredoxins.

Publications

Phosphines are ribonucleotide reductase reductants that act via C-terminal cysteines similar to thioredoxins and glutaredoxins.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure