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| | {{STRUCTURE_1mk6| PDB=1mk6 | SCENE= }} | | {{STRUCTURE_1mk6| PDB=1mk6 | SCENE= }} |
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| - | '''SOLUTION STRUCTURE OF THE 8,9-DIHYDRO-8-(N7-GUANYL)-9-HYDROXY-AFLATOXIN B1 ADDUCT MISPAIRED WITH DEOXYADENOSINE'''
| + | ===SOLUTION STRUCTURE OF THE 8,9-DIHYDRO-8-(N7-GUANYL)-9-HYDROXY-AFLATOXIN B1 ADDUCT MISPAIRED WITH DEOXYADENOSINE=== |
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| - | ==Overview==
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| - | The G --> T transversion is the dominant mutation induced by the cationic trans-8,9-dihydro-8-(N7-guanyl)-9-hydroxy-aflatoxin B(1) adduct. The structure of d(ACATC(AFB)GATCT).d(AGATAGATGT), in which the cationic adduct was mismatched with deoxyadenosine, was refined using molecular dynamics calculations restrained by NOE data and dihedral restraints obtained from NMR spectroscopy. Restrained molecular dynamics calculations refined structures with pairwise rmsd <1 A and a sixth root R1x factor between the refined structure and NOE data of 10.5 x 10-2. The mismatched duplex existed in a single conformation at neutral pH. The aflatoxin moiety intercalated above the 5' face of the modified (AFB)G. The mismatched dA was in the anti conformation about the glycosyl bond. It extruded toward the major groove and did not participate in hydrogen bonding with (AFB)G. The structure was compared with that of d(ACATCGATCT).d(AGATAGATGT) containing the corresponding unmodified G.A mismatch and with d(ACATC(AFB)GATCT).d(AGATCGATGT) containing the aflatoxin lesion in the correctly paired (AFB)G.C context. The correctly paired oligodeoxynucleotide exhibited Watson-Crick-type geometry at the (AFB)G.C pair. It melted at higher temperature than the mismatched (AFB)G.A duplex. The unmodified mismatched G.A duplex exhibited spectral line broadening at neutral pH, suggesting a mixture of conformations. It exhibited a lower melting temperature than did the mismatched (AFB)G.A duplex. These differences correlated with replication bypass experiments performed in vitro utilizing DNA polymerase I exo- [Johnston, D. S., and Stone, M. P. (2000) Chem. Res. Toxicol. 13, 1158-1164]. Those experiments showed that correct insertion of dC opposite (AFB)G blocked replication by the enzyme, whereas incorrect insertion of dA opposite (AFB)G allowed full-length replication of the adducted template strand.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_11969407}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 11969407 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_11969407}} |
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| | ==About this Structure== | | ==About this Structure== |
| - | Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1MK6 OCA]. | + | Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1MK6 OCA]. |
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| | ==Reference== | | ==Reference== |
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| | [[Category: Aflatoxin b1- guanine adduct opposite an adenine]] | | [[Category: Aflatoxin b1- guanine adduct opposite an adenine]] |
| | [[Category: Mimicking ga transition]] | | [[Category: Mimicking ga transition]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 01:15:48 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Jul 3 00:09:45 2008'' |
Revision as of 21:09, 2 July 2008
Template:STRUCTURE 1mk6
SOLUTION STRUCTURE OF THE 8,9-DIHYDRO-8-(N7-GUANYL)-9-HYDROXY-AFLATOXIN B1 ADDUCT MISPAIRED WITH DEOXYADENOSINE
Template:ABSTRACT PUBMED 11969407
About this Structure
Full experimental information is available from OCA.
Reference
Mispairing of the 8,9-dihydro-8-(N7-guanyl)-9-hydroxy-aflatoxin B1 adduct with deoxyadenosine results in extrusion of the mismatched dA toward the major groove., Giri I, Johnston DS, Stone MP, Biochemistry. 2002 Apr 30;41(17):5462-72. PMID:11969407
Page seeded by OCA on Thu Jul 3 00:09:45 2008
