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Euglena gracilis ribonucleotide reductase: the eukaryote class II enzyme and the possible antiquity of eukaryote B12 dependence
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm , Ludwig Institute for Cancer Research.
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2006 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 281, no 9, 5604-5611 p.Article in journal (Refereed) Published
Abstract [en]

Ribonucleotide reductases provide the building blocks for DNA synthesis. Three classes of enzymes are known, differing widely in amino acid sequence but with similar structural motives and allosteric regulation. Class I occurs in eukaryotes and aerobic prokaryotes, class II occurs in aerobic and anaerobic prokaryotes, and class III occurs in anaerobic prokaryotes. The eukaryote Euglena gracilis contains a class II enzyme (Gleason, F. K., and Hogenkamp, H. P. (1970) J. Biol. Chem. 245, 4894-4899) and, thus, forms an exception. Class II enzymes depend on vitamin B(12) for their activity. We purified the reductase from Euglena cells, determined partial peptide sequences, identified its cDNA, and purified the recombinant enzyme. Its amino acid sequence and general properties, including its allosteric behavior, were similar to the class II reductase from Lactobacillus leichmannii. Both enzymes belong to a distinct small group of reductases that unlike all other homodimeric reductases are monomeric. They compensate the loss of the second polypeptide of dimeric enzymes by a large insertion in the monomeric chain. Data base searching and sequence comparison revealed a homolog from the eukaryote Dictyostelium discoideum as the closest relative to the Euglena reductase, suggesting that the class II enzyme was present in a common, B(12)-dependent, eukaryote ancestor.

Place, publisher, year, edition, pages
2006. Vol. 281, no 9, 5604-5611 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-78724DOI: 10.1074/jbc.M512962200PubMedID: 16368684OAI: oai:DiVA.org:uu-78724DiVA: diva2:106637
Available from: 2006-03-29 Created: 2006-03-29 Last updated: 2011-02-28Bibliographically approved

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