Insight into the Functional Consequences of Inherited Variants of the hMYH Adenine Glycosylase Associated with Colorectal Cancer: Complementation Assays with hMYH Variants and Pre-steady-state Kinetics of the Corresponding Mutated E.coli Enzymes

Chmiel, Nikolas H.; Livingston, Alison L.; David, Sheila S.

doi:10.1016/s0022-2836(03)00124-4

Cited by 90 publications

(107 citation statements)

References 51 publications

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“…30 MutY exhibits particularly high affinities for duplexes containing OG:FA bps (K d = 0.8 ± 0.4 nM). 25,31 The extents of conversion of OG:FA to G:C was significantly less than that observed with OG:A and OG:Z3 in the presence of MutY (57 ± 2 %). The G:FA mismatch was converted to G:C (44 ± 1 %) at a level that was similar to G:A and G:Z3 in the presence of MutY (Fig.…”

Section: Cellular Repair Of Og:fa and G:fa Mismatchesmentioning

confidence: 70%

“…25,32,33 In these experiments, the absence of MutY activity allows spontaneous mutations in the rifampicin binding site of E. coli RNA polymerase to accumulate and render rifampicin less effective as a block to transcription. 14,34,35 However, such assays are not readily adaptable to evaluating the repair of a specific damaged DNA substrate or unnatural synthetic DNA nucleotides.…”

Section: Discussionmentioning

confidence: 99%

“…The magnitude of the preference for OG:A over G:A with duplex 1 is greater than with duplex 2 (50-fold versus 10-fold) due to the reduced rate constant for G:A in duplex 1 compared to duplex 2. 17,25 The higher salt concentration had an even more dramatic effect on the reaction of MutY with G:A substrates. In duplex 2 at 150 mM NaCl, the rate constant k 2 for adenine removal with the G:A substrate is reduced by approximately 70-fold compared to the value with the OG:A duplex.…”

Section: Glycosylase Activity Of Muty With Modified Substratesmentioning

confidence: 99%

“…10,24 The two most common missense amino acid substitutions in MUTYH result in reduced glycosylase activity and affinity for OG-containing substrates. 40 In addition, the corresponding E. coli variants are unable to distinguish OG from G. 25,36 This suggests that the function of MutY and its human homologue to prevent deleterious DNA mutations is critically dependent on the ability to detect OG and select the appropriate undamaged A for excision to initiate BER. …”

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Unnatural substrates reveal the importance of 8-oxoguanine for in vivo mismatch repair by MutY

et al. 2007

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Escherchia coli MutY plays an important role in preventing mutations associated with the oxidative lesion 7,8-dihydro-8-oxo-2′-deoxyguanosine (OG) in DNA by excising adenines from OG:A mismatches as the first step of base excision repair. To determine the importance of specific steps in the base pair recognition and base removal process of MutY, we have evaluated the effects of modifications of the OG:A substrate on the kinetics of base removal, mismatch affinity and repair to G:C in an Escherchia coli-based assay. Surprisingly, adenine modification was tolerated in the cellular assay, while modification of OG results in minimal cellular repair. High affinity for the mismatch and efficient base removal require the presence of OG. Taken together, these results suggest that the presence of OG is a critical feature for MutY to locate OG:A mismatches and select the appropriate adenines for excision to initiate repair in vivo prior to replication.The mismatch repair (MMR) pathway in E. coli relies on methylation at a GATC sequence to direct the repair machinery to remove the mismatched base on the newly synthesized strand. 1 However, almost two decades ago, an activity was detected in E. coli cell extracts that restored G:A mismatches to G:C matches and was insensitive to the methylation state of the template strand. [2][3][4] Concurrently, a mutator locus in E. coli (mutY) was identified that generated G:C → T:A transversion mutations. 5 It was later determined that the mutY gene product is an adenine glycosylase capable of removing adenines from G:A mismatches as the first step in base excision repair (BER). [6][7][8][9][10] The subsequent activity of downstream BER pathway enzymes, e.g. the AP endonuclease, deoxyribophosphate lyase, polymerase and ligase, restores the G:C base pair in a methylation-independent fashion. 11 MutY was also found to participate in the prevention of mutations caused by 7,8-dihydro-8-oxo-2′-deoxyguanosine (OG, 1) by removal of adenine from OG:A mismatches. 10,12,13,14 Polymerase misinsertion of dAMP opposite OG creates OG:A mismatches that can lead to formation of T:A base pairs upon a second round of replication. 12 Recently, MutY has been in the spotlight due to the correlation between inherited biallelic mutations in the gene encoding the human homologue of MutY (MUTYH) and colorectal cancer. 10,15,16 *Author to whom correspondence should be addressed. Email: david@chem.ucdavis.edu,. # These authors contributed equally to this manuscript. We have previously examined the features of mismatched substrates that are required for efficient lesion recognition and adenine excision by MutY using pre-steady state and singleturnover kinetics. [17][18][19] Pre-steady state experiments revealed that MutY has a high affinity for the product such that release of the DNA product is rate-limiting. 17,19,20 Moreover, the identity of the base opposite A greatly affects both the rate of product release as well as the intrinsic rate of adenine removal determined under single-turnover conditions....

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Section: Cellular Repair Of Og:fa and G:fa Mismatchesmentioning

confidence: 70%

Section: Discussionmentioning

confidence: 99%

Section: Glycosylase Activity Of Muty With Modified Substratesmentioning

confidence: 99%

mentioning

confidence: 99%

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Unnatural substrates reveal the importance of 8-oxoguanine for in vivo mismatch repair by MutY

et al. 2007

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“…David and coworkers have introduced the mutations corresponding to the Y165C and G382D human variants into the E. coli homolog of MYH and found that adenine glycosylase activity in certain sequence contexts was significantly reduced by either of these mutations. 66,67 No functional studies have been carried out with the P391S and Q400R gastric tumor-associated variants. However, the authors of this study note that gastric carcinomas often arise as a result of infection with H. pylori, 65 which results in production of reactive oxygen species (ROS) and increased levels of 8-oxoG in the DNA.…”

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confidence: 99%

Is Base Excision Repair a Tumor Suppressor Mechanism?

Sweasy¹,

Lang²,

DiMaio³

2006

Cell Cycle

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The base excision repair pathway is critical for the removal of oxidized and methylated bases from the DNA. Much of this DNA damage arises endogenously, as a result of oxygen metabolism. Several proteins including DNA glycosylases, the APE1 endonuclease, DNA polymerase β and DNA ligase, act in a highly regulated and coordinated manner during base excision repair to excise the base adducts from the DNA and restore the normal DNA sequence. Both germline and tumor-associated variants of genes encoding these proteins have been identified in humans. In many cases, the protein variant has been shown to have properties that could contribute to the development of cancer, suggesting that base excision repair acts as a tumor suppressor mechanism in humans. Limited epidemiological studies are consistent with this view. Our review of the literature indicates that additional laboratory and epidemiological studies of the role of base excision repair in cancer etiology is warranted.

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Synthesis of Oligonucleotides Containing the N⁶‐(2‐Deoxy‐α,β‐d‐erythropentofuranosyl)‐2,6‐diamino‐4‐hydroxy‐5‐formamidopyrimidine (Fapy⋅dG) Oxidative Damage Product Derived from 2′‐Deoxyguanosine

Yang

Tang

Greenberg

2020

Chemistry A European J

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N 6 -(2-Deoxy-a,b-d-erythropentofuranosyl)-2,6-diamino-4-hydroxy-5-formamidopyrimidine (Fapy·dG)i sa major DNA lesion produced from 2'-deoxyguanosine under oxidizing conditions. Fapy·dG is produced from ac ommon intermediate that leads to 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-OxodGuo), andi ng reater quantities in cells. The impact of Fapy·dG on DNA structure and functioni sm uch less well understood than that of 8-OxodGuo. This is largely due to the significantly greaterd ifficulty in synthesizing oligonucleotides containing Fapy·dG than 8-OxodGuo.W ed escribe as ynthetic approach for preparing oligonucleotides containing Fapy·dG that will facilitate intensive studies of this lesion in DNA. Av ariety of oligonucleotides as long as 30 nucleotides are synthesized. We anticipate that the chemistry described herein will provide an impetus for a wide range of studies involving Fapy·dG.Scheme1.Formation of Fapy·dG and 8-OxodGuo.[a] Dr.

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Insight into the Functional Consequences of Inherited Variants of the hMYH Adenine Glycosylase Associated with Colorectal Cancer: Complementation Assays with hMYH Variants and Pre-steady-state Kinetics of the Corresponding Mutated E.coli Enzymes

Cited by 90 publications

References 51 publications

Unnatural substrates reveal the importance of 8-oxoguanine for in vivo mismatch repair by MutY

Unnatural substrates reveal the importance of 8-oxoguanine for in vivo mismatch repair by MutY

Is Base Excision Repair a Tumor Suppressor Mechanism?

Synthesis of Oligonucleotides Containing the N⁶‐(2‐Deoxy‐α,β‐d‐erythropentofuranosyl)‐2,6‐diamino‐4‐hydroxy‐5‐formamidopyrimidine (Fapy⋅dG) Oxidative Damage Product Derived from 2′‐Deoxyguanosine

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Insight into the Functional Consequences of Inherited Variants of the hMYH Adenine Glycosylase Associated with Colorectal Cancer: Complementation Assays with hMYH Variants and Pre-steady-state Kinetics of the Corresponding Mutated E.coli Enzymes

Cited by 90 publications

References 51 publications

Unnatural substrates reveal the importance of 8-oxoguanine for in vivo mismatch repair by MutY

Unnatural substrates reveal the importance of 8-oxoguanine for in vivo mismatch repair by MutY

Is Base Excision Repair a Tumor Suppressor Mechanism?

Synthesis of Oligonucleotides Containing the N6‐(2‐Deoxy‐α,β‐d‐erythropentofuranosyl)‐2,6‐diamino‐4‐hydroxy‐5‐formamidopyrimidine (Fapy⋅dG) Oxidative Damage Product Derived from 2′‐Deoxyguanosine

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Synthesis of Oligonucleotides Containing the N⁶‐(2‐Deoxy‐α,β‐d‐erythropentofuranosyl)‐2,6‐diamino‐4‐hydroxy‐5‐formamidopyrimidine (Fapy⋅dG) Oxidative Damage Product Derived from 2′‐Deoxyguanosine