PMID- 10346901
OWN - NLM
STAT- MEDLINE
DCOM- 19990623
LR  - 20151119
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 38
IP  - 21
DP  - 1999 May 25
TI  - Reaction and binding of oligodeoxynucleotides containing analogues of 
      O6-methylguanine with wild-type and mutant human O6-alkylguanine-DNA 
      alkyltransferase.
PG  - 6801-6
AB  - O6-Alkylguanine-DNA alkyltransferase (AGT) repairs DNA by transferring the methyl 
      group from the 6-position of guanine to a cysteine residue on the protein. We 
      previously found that the Escherichia coli Ada protein makes critical 
      interactions with O6-methylguanine (O6mG) at the N1- and O6-positions. Human AGT 
      has a different specificity than the bacterial protein. We reacted hAGT with 
      double-stranded pentadecadeoxynucleotides containing analogues of O6mG. The 
      second-order rate constants were in the following order (x10(-)5 M-1 s-1): O6mG 
      (1.4), O6-methylhypoxanthine (1.6) > Se6-methyl-6-selenoguanine (0.1) > 
      S6-methyl-6-thioguanine (S6mG) (0.02) >> S6-methyl-6-thiohypoxanthine (S6mH), 
      O6-methyl-1-deazaguanine (O6m1DG), O6-methyl-3-deazaguanine (O6m3DG), and 
      O6-methyl-7-deazaguanine (O6m7DG) (all <0.0001). Electrophoretic mobility shift 
      assays were carried out to determine the binding affinity to hAGT. 
      Oligodeoxynucleotides containing O6mG, S6mG and O6m3DG bound to AGT in the 
      presence of competitor DNA with Kd values from 5 to 20 microM, while those 
      containing G, S6mH, O6m1DG, and O6m7DG did not (Kd > 200 microM). These results 
      indicate that the 1-, N2-, and 7- positions of O6mG are critical in binding to 
      hAGT, while the 3- and O6-positions are involved in methyl transfer. These 
      results suggest that the active site of ada AGT is more flexible than hAGT and 
      may be the reason ada AGT reacts with O4mT faster than hAGT.
FAU - Spratt, T E
AU  - Spratt TE
AD  - American Health Foundation, Division of Pathology and Toxicology, Valhalla, New 
      York 10595, USA.
FAU - Wu, J D
AU  - Wu JD
FAU - Levy, D E
AU  - Levy DE
FAU - Kanugula, S
AU  - Kanugula S
FAU - Pegg, A E
AU  - Pegg AE
LA  - eng
GR  - CA 18137/CA/NCI NIH HHS/United States
GR  - CA 75074/CA/NCI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (Nucleic Acid Heteroduplexes)
RN  - 0 (Oligodeoxyribonucleotides)
RN  - 5Z93L87A1R (Guanine)
RN  - 9B710FV2AE (O-(6)-methylguanine)
RN  - EC 2.1.1.63 (O(6)-Methylguanine-DNA Methyltransferase)
SB  - IM
MH  - Binding Sites/genetics
MH  - DNA Repair
MH  - Guanine/*analogs & derivatives/chemistry/metabolism
MH  - Humans
MH  - Kinetics
MH  - Mutagenesis
MH  - Nucleic Acid Heteroduplexes/chemistry/metabolism
MH  - O(6)-Methylguanine-DNA Methyltransferase/*chemistry/*genetics/metabolism
MH  - Oligodeoxyribonucleotides/*chemistry/metabolism
MH  - Protein Binding/genetics
MH  - Structure-Activity Relationship
MH  - Substrate Specificity/genetics
EDAT- 1999/05/29 00:00
MHDA- 1999/05/29 00:01
CRDT- 1999/05/29 00:00
PHST- 1999/05/29 00:00 [pubmed]
PHST- 1999/05/29 00:01 [medline]
PHST- 1999/05/29 00:00 [entrez]
AID - bi982908w [pii]
AID - 10.1021/bi982908w [doi]
PST - ppublish
SO  - Biochemistry. 1999 May 25;38(21):6801-6. doi: 10.1021/bi982908w.