The Methanothermobacter thermautotrophicus ExoIII homologue Mth212 is a DNA uridine endonuclease.
The genome of Methanothermobacter thermautotrophicus, as a hitherto unique case, is apparently devoid of genes coding for general uracil DNA glycosylases, the universal mediators of base excision repair following hydrolytic deamination of DNA cytosine residues. We have now identified protein Mth212, a member of the ExoIII family of nucleases, as a possible initiator of DNA uracil repair in this organism. This enzyme, in addition to bearing all the enzymological hallmarks of an ExoIII homologue, is a DNA uridine endonuclease (U-endo) that nicks double-stranded DNA at the 5'-side of a 2'-d-uridine residue, irrespective of the nature of the opposing nucleotide. This type of activity has not been described before; it is absent from the ExoIII homologues of Escherichia coli, Homo sapiens and Methanosarcina mazei, all of which are equipped with uracil DNA repair glycosylases. The U-endo activity of Mth212 is served by the same catalytic center as its AP-endo activity.
Georg
Jens
J
Abteilung Molekulare Genetik und Präparative Molekularbiologie, Institut für Mikrobiologie und Genetik Georg-August-Universität, Göttingen, Grisebachstrasse 8, 37077 Göttingen, Germany.
Schomacher
Lars
L
Chong
James P J
JP
Majerník
Alan I
AI
Raabe
Monika
M
Urlaub
Henning
H
Müller
Sabine
S
Ciirdaeva
Elena
E
Kramer
Wilfried
W
Fritz
Hans-Joachim
HJ
D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002384:Catalysis; D002457:Cell Extracts / Q000737:chemistry; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005090:Exodeoxyribonucleases / Q000737:chemistry; D019766:Genes, Archaeal; D017013:Methanobacteriaceae / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D014529:Uridine / Q000378:metabolism*
D019843:Archaeal Proteins; D002457:Cell Extracts; D004247:DNA; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; C020133:exodeoxyribonuclease III; D014529:Uridine