Biochemical characterization of uracil processing activities in the hyperthermophilic archaeon Pyrobaculum aerophilum

Sartori, A. A. and Schär, P. and Fitz-Gibbon, S. and Miller, J. H. and Jiricny, J.. (2001) Biochemical characterization of uracil processing activities in the hyperthermophilic archaeon Pyrobaculum aerophilum. Journal of biological chemistry, Vol. 276, H. 32. pp. 29979-29986.

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Official URL: http://edoc.unibas.ch/dok/A5839363

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Deamination of cytosine to uracil and 5-methylcytosine to thymine represents a major mutagenic threat particularly at high temperatures. In double-stranded DNA, these spontaneous hydrolytic reactions give rise to G.U and G.T mispairs, respectively, that must be restored to G.C pairs prior to the next round of DNA replication; if left unrepaired, 50% of progeny DNA would acquire G.C --< A.T transition mutations. The genome of the hyperthermophilic archaeon Pyrobaculum aerophilum has been recently shown to encode a protein, Pa-MIG, a member of the endonuclease III family, capable of processing both G.U and G.T mispairs. We now show that this latter activity is undetectable in crude extracts of P. aerophilum. However, uracil residues in G.U mispairs, in A.U pairs, and in single-stranded DNA were efficiently removed in these extracts. These activities were assigned to a approximately 22-kDa polypeptide named Pa-UDG (P. aerophilum uracil-DNA glycosylase). The recombinant Pa-UDG protein is highly thermostable and displays a considerable degree of homology to the recently described uracil-DNA glycosylases from Archaeoglobus fulgidus and Thermotoga maritima. Interestingly, neither Pa-MIG nor Pa-UDG was inhibited by UGI, a generic inhibitor of the UNG family of uracil glycosylases. Yet a small fraction of the total uracil processing activity present in crude extracts of P. aerophilum was inhibited by this peptide. This implies that the hyperthermophilic archaeon possesses at least a three-pronged defense against the mutagenic threat of hydrolytic deamination of cytosines in its genomic DNA.
Faculties and Departments:03 Faculty of Medicine > Departement Biomedizin > Division of Biochemistry and Genetics > Molecular Genetics (Schär)
UniBasel Contributors:Schär, Primo Leo
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Society of Biological Chemists
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:24 May 2013 09:10
Deposited On:26 Apr 2013 06:57

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