Effects of diaminopurine and inosine substitutions on A-tract induced DNA curvature. Importance of the 3'-A-tract junction

TY - JOUR

T1 - Effects of diaminopurine and inosine substitutions on A-tract induced DNA curvature. Importance of the 3'-A-tract junction

AU - Mollegaard, N E

AU - Bailly, C

AU - Waring, M J

AU - Nielsen, Peter E.

PY - 1997/9/1

Y1 - 1997/9/1

N2 - Gel migration and uranyl photoprobing have been used to study the effects of inosine and 2,6-diaminopurine (2,6-DAP) substitution on adenine-tract (A-tract) induced DNA curvature. Using a 10mer repeated sequence including five inosines we show by uranyl photoprobing that a narrow minor groove varying in phase with the helix repeat is not the cause of DNA curvature. Further, we have systematically studied by gel migration the effects on A-tract induced curvature of either single or full substitution with inosine and/or 2,6-DAP in a 5'-AAAAAGCCGC-3'sequence. DNA curvature is shown to increase when inosines are substituted for the guanosines in the sequence between the A-tracts. By comparing the effects of each monosubstitution it can be seen that when the G closest to the 3'-end of the A-tract is substituted the effect on DNA curvature is much stronger than when substitution is made at any other position. By contrast, curvature is abolished when 2,6-DAP residues are substituted for all adenines, and monosubstitution reveals that the effect of substituting a single adenine is strongest at the 3'-end of the A-tract. These results favor a model in which the curvature induced by an A-tract in DNA molecules is primarily located at the junction with the 3'-end of the A-tract, and this peculiar junction is created because the A-tract has a preference to form a non-B-DNA structure which builds up from the 5'-end.

AB - Gel migration and uranyl photoprobing have been used to study the effects of inosine and 2,6-diaminopurine (2,6-DAP) substitution on adenine-tract (A-tract) induced DNA curvature. Using a 10mer repeated sequence including five inosines we show by uranyl photoprobing that a narrow minor groove varying in phase with the helix repeat is not the cause of DNA curvature. Further, we have systematically studied by gel migration the effects on A-tract induced curvature of either single or full substitution with inosine and/or 2,6-DAP in a 5'-AAAAAGCCGC-3'sequence. DNA curvature is shown to increase when inosines are substituted for the guanosines in the sequence between the A-tracts. By comparing the effects of each monosubstitution it can be seen that when the G closest to the 3'-end of the A-tract is substituted the effect on DNA curvature is much stronger than when substitution is made at any other position. By contrast, curvature is abolished when 2,6-DAP residues are substituted for all adenines, and monosubstitution reveals that the effect of substituting a single adenine is strongest at the 3'-end of the A-tract. These results favor a model in which the curvature induced by an A-tract in DNA molecules is primarily located at the junction with the 3'-end of the A-tract, and this peculiar junction is created because the A-tract has a preference to form a non-B-DNA structure which builds up from the 5'-end.

KW - 2-Aminopurine/analogs & derivatives

KW - Adenine/chemistry

KW - Base Sequence

KW - DNA/chemistry

KW - Deoxyribonuclease EcoRI

KW - Deoxyribonucleases, Type II Site-Specific

KW - Electrophoresis, Polyacrylamide Gel

KW - Inosine/chemistry

KW - Nucleic Acid Conformation

KW - Photochemistry

KW - Polymerase Chain Reaction

KW - Repetitive Sequences, Nucleic Acid

KW - Structure-Activity Relationship

KW - Uranyl Nitrate

M3 - Journal article

C2 - 9254710

SN - 0305-1048

VL - 25

SP - 3497

EP - 3502

JO - Nucleic Acids Research

JF - Nucleic Acids Research

IS - 17

ER -