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Biosci Biotechnol Biochem. 2017 May;81(5):931-937. doi: 10.1080/09168451.2016.1277946. Epub 2017 Jan 18.

A functional endonuclease Q exists in the bacterial domain: identification and characterization of endonuclease Q from Bacillus pumilus.

Shiraishi M1,2,3, Ishino S1, Cann I4,5,2,3, Ishino Y1,2,3.

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a Graduate School of Bioresource and Bioenvironmental Sciences , Kyushu University , Fukuoka , Japan.
d Institute for Universal Biology , University of Illinois at Urbana-Champaign , Urbana , IL , USA.
e Carl R. Woese Institute for Genomic Biology , University of Illinois at Urbana-Champaign , Urbana , IL , USA.
b Department of Animal Science , University of Illinois at Urbana-Champaign , Urbana , IL , USA.
c Department of Microbiology , University of Illinois at Urbana-Champaign , Urbana , IL , USA.


DNA base deamination occurs spontaneously under physiological conditions and is promoted by high temperature. Therefore, hyperthermophiles are expected to have efficient repair systems of the deaminated bases in their genomes. Endonuclease Q (EndoQ) was originally identified from the hyperthermophlic archaeon, Pyrococcus furiosus, as a hypoxanthine-specific endonuclease recently. Further biochemical analyses revealed that EndoQ also recognizes uracil, xanthine, and the AP site in DNA, and is probably involved in a specific repair process for damaged bases. Initial phylogenetic analysis showed that an EndoQ homolog is found only in the Thermococcales and some of the methanogens in Archaea, and is not present in most members of the domains Bacteria and Eukarya. A better understanding of the distribution of the EndoQ-mediated repair system is, therefore, of evolutionary interest. We showed here that an EndoQ-like polypeptide from Bacillus pumilus, belonging to the bacterial domain, is functional and has similar properties with the archaeal EndoQs.


Archaea; DNA repair; base deamination; endonuclease; molecular evolution

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