Definitive Identification of Mammalian 5-Hydroxymethyluracil DNA N-Glycosylase Activity as SMUG1

Boorstein, Robert J.; Cummings, Archie; Marenstein, Dina R.; Chan, Michael K.; Ma, Yuliang; Neubert, Thomas A.; Brown, Stuart M.; Teebor, George W.

doi:10.1074/jbc.m106953200

Cited by 131 publications

(110 citation statements)

References 22 publications

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“…This property has been reported in AP endonucleases as hApeI (37) and Chlamydia pneumoniae AP endonuclease IV (38). In addition, other enzymes involved in BER, as several phylogenetically diverse DNA N-glycosylases, have shown activity against damaged bases in ssDNA (39)(40)(41)(42)(43)(44)(45). The presence of abasic sites in ssDNA regions is highly deleterious because, in addition to block replication and transcription, the nicking action of a canonical AP endonuclease could induce lethal dsDNA breaks.…”

Section: Resultsmentioning

confidence: 99%

Intrinsic apurinic/apyrimidinic (AP) endonuclease activity enables Bacillus subtilis DNA polymerase X to recognize, incise, and further repair abasic sites

Baños

Villar

Salas

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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The N-glycosidic bond can be hydrolyzed spontaneously or by glycosylases during removal of damaged bases by the base excision repair pathway, leading to the formation of highly mutagenic apurinic/apyrimidinic (AP) sites. Organisms encode for evolutionarily conserved repair machinery, including specific AP endonucleases that cleave the DNA backbone 5′ to the AP site to prime further DNA repair synthesis. We report on the DNA polymerase X from the bacterium Bacillus subtilis (PolX Bs ) that, along with polymerization and 3′-5′-exonuclease activities, possesses an intrinsic AP-endonuclease activity. Both, AP-endonuclease and 3′-5′-exonuclease activities are genetically linked and governed by the same metal ligands located at the C-terminal polymerase and histidinol phosphatase domain of the polymerase. The different catalytic functions of PolX Bs enable it to perform recognition and incision at an AP site and further restoration (repair) of the original nucleotide in a standalone AP-endonuclease-independent way. apurinic/apyrimidinic-lyase | site-directed mutagenesis G enomes are continuously insulted by exogenous and endogenous genotoxic agents, as ionizing radiation, drugs, and (by)products of normal cellular metabolism that generate reactive oxygen species (ROS) leading to mainly nonbulky DNA lesions (1). Base excision repair (BER) is the major pathway involved in the removal of this type of damage, and its importance for cell survival is reflected by its conservation from bacteria to eukaryotes (2). During the first steps of BER, highly mutagenic apurinic/apyrimidinic (AP) intermediates are produced as a result of hydrolytic cleavage of the altered base-sugar bond by mono-(class II) and/or bifunctional (class I) DNA N-glycosylases (ref. 3 and references therein), or from spontaneous DNA base loss, causing replication and transcription inhibition if left unrepaired (4, 5). AP endonucleases play a crucial role in BER because they recognize the abasic residue and hydrolyze the phosphodiester bond 5′ to the AP site, leaving a gapped DNA intermediate with an extendable 3′-OH end (ref. 2 and references therein).Members of the family X of DNA polymerases (hereafter, PolX) are widely spread in nature from virus to humans, being involved in the DNA synthesis step during BER and DNA double-strand break repair by virtue of a common Polβ-like core adapted to fill the gapped DNA intermediates very proficiently (6-9).PolX Bs (570-aa long) is a prototypic bacterial/archaeal PolX member from Bacillus subtilis with a N-terminal Polβ-like core (residues 1-317) responsible for catalysis of DNA polymerization (10), and a C-terminal polymerase and histidinol phosphatase (PHP) domain (residues 333-570) containing highly conserved residues that catalyze a Mn 2þ -dependent 3′-5′-exonuclease activity (11-14), which shows a preferential processing of unannealed 3′ termini (12). Due to this fact and to its adaptation to perform filling of small gaps (10), PolX Bs was proposed to play a potential role in the DNA synthesis step of repair p...

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Section: Resultsmentioning

confidence: 99%

Intrinsic apurinic/apyrimidinic (AP) endonuclease activity enables Bacillus subtilis DNA polymerase X to recognize, incise, and further repair abasic sites

Baños

Villar

Salas

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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“…The first step of this pathway is the conversion of 5hmC to 5-hydroxymethyluracil (5hmU) by AID/ APOBEC, followed by TDG-or single-strand-selective monofunctional uracil DNA glycosylase (SMUG1)-mediated BER to generate unmethylated cytosine (Fig. 2) [41,42]. Of note, Aid-deficient BM cells demonstrated a significant accumulation of 5hmC compared to wild-type cells, consistent with deaminase activity of Aid on 5hmC [43].…”

Section: Tet2mentioning

confidence: 97%

Epigenetic dysregulation of hematopoietic stem cells and preleukemic state

Kunimoto

Nakajima

2017

Int J Hematol

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“…xSMUG1 acted upon U : G and U : A essentially without preference for either, but showed no enzymatic activity against T : G, in contrast to the T(U)-mismatch glycosylase TDG (Hardeland et al, 2001). Recently, it was found that SMUG1 is probably the major enzyme for removal of 5-hmeU (Boorstein et al, 1987) from DNA (Boorstein et al, 2001). 5-hmeU is a result of oxidation of the 5-methyl group of thymine in DNA due to ionizing radiation and other forms of oxidative stress (Faure et al, 1998).…”

Section: Smug1 (Single Strand-selective Monofunctionalmentioning

confidence: 99%