The B12-dependent ribonucleotide reductase from the archaebacterium Thermoplasma acidophila: an evolutionary solution to the ribonucleotide reductase conundrum.

ABSTRACT: 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. acidophil

SUBMITTER: Tauer A 

PROVIDER: S-EPMC19235 | biostudies-literature | 1997 Jan

REPOSITORIES: biostudies-literature