Abstract
The effect of the central non-Pur·Pyr sequences in oligo(dG·dC) inserts on determining the type of intramolecular DNA triplex isomers formed in negatively supercoiled plasmids was investigated. Different triplex types (H- r3, H-r5, and H-y3), revealed by a combination of chemical probing and Maxam- Gilbert sequencing reactions, were adopted by the oligo(dG·dC) tracts depending on the length and composition of the central non-Pur·Pyr sequences (0, 3, or 5 base pairs) and the kind of metal ions. The H-r3 triplex conformer, one isomer of a Pur·Pur·Pyr structure, was formed in the (C)20 and (C)10GCG(C)10 inserts in plasmids in the presence of certain metal ions. Interestingly, H-r5, the other isomer of the Pur·Pur·Pyr triplex which had not been detected previously, was formed in a (C)9GAATT(C)9 insert in the presence of either Mg2+ or Ca2+. Alternatively, H-y3, one isomer of a Pyr·Pur·Pyr triplex, was formed in the (C)9GAATT(C)9 insert in the absence of metal ions. Thus, central non-Pur·Pyr sequences and metal ions play a role as determinants of the types of intramolecular triplexes formed; they also reduce the requirement of longer Pur·Pyr repeat sequences to form intramolecular triplexes. Furthermore, the effects of MgCl2 concentration and pH on the formation of triplex isomers were examined. The Pur·Pur·Pyr conformations (H-r3 and H-r5) may be the favored conformations in the cellular milieu, since they are stable at physiological pH and metal ion concentration.
| Original language | English |
|---|---|
| Pages (from-to) | 20887-20891 |
| Number of pages | 5 |
| Journal | Journal of Biological Chemistry |
| Volume | 267 |
| Issue number | 29 |
| Publication status | Published - 1992 Jan 1 |
| Externally published | Yes |
Fingerprint
ASJC Scopus subject areas
- Biochemistry
Cite this
Central non-Pur·Pyr sequences in oligo(dG·dC) tracts and metal ions influence the formation of intramolecular DNA triplex isomers. / Kang, Seong Man; Wells, R. D.
In: Journal of Biological Chemistry, Vol. 267, No. 29, 01.01.1992, p. 20887-20891.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Central non-Pur·Pyr sequences in oligo(dG·dC) tracts and metal ions influence the formation of intramolecular DNA triplex isomers
AU - Kang, Seong Man
AU - Wells, R. D.
PY - 1992/1/1
Y1 - 1992/1/1
N2 - The effect of the central non-Pur·Pyr sequences in oligo(dG·dC) inserts on determining the type of intramolecular DNA triplex isomers formed in negatively supercoiled plasmids was investigated. Different triplex types (H- r3, H-r5, and H-y3), revealed by a combination of chemical probing and Maxam- Gilbert sequencing reactions, were adopted by the oligo(dG·dC) tracts depending on the length and composition of the central non-Pur·Pyr sequences (0, 3, or 5 base pairs) and the kind of metal ions. The H-r3 triplex conformer, one isomer of a Pur·Pur·Pyr structure, was formed in the (C)20 and (C)10GCG(C)10 inserts in plasmids in the presence of certain metal ions. Interestingly, H-r5, the other isomer of the Pur·Pur·Pyr triplex which had not been detected previously, was formed in a (C)9GAATT(C)9 insert in the presence of either Mg2+ or Ca2+. Alternatively, H-y3, one isomer of a Pyr·Pur·Pyr triplex, was formed in the (C)9GAATT(C)9 insert in the absence of metal ions. Thus, central non-Pur·Pyr sequences and metal ions play a role as determinants of the types of intramolecular triplexes formed; they also reduce the requirement of longer Pur·Pyr repeat sequences to form intramolecular triplexes. Furthermore, the effects of MgCl2 concentration and pH on the formation of triplex isomers were examined. The Pur·Pur·Pyr conformations (H-r3 and H-r5) may be the favored conformations in the cellular milieu, since they are stable at physiological pH and metal ion concentration.
AB - The effect of the central non-Pur·Pyr sequences in oligo(dG·dC) inserts on determining the type of intramolecular DNA triplex isomers formed in negatively supercoiled plasmids was investigated. Different triplex types (H- r3, H-r5, and H-y3), revealed by a combination of chemical probing and Maxam- Gilbert sequencing reactions, were adopted by the oligo(dG·dC) tracts depending on the length and composition of the central non-Pur·Pyr sequences (0, 3, or 5 base pairs) and the kind of metal ions. The H-r3 triplex conformer, one isomer of a Pur·Pur·Pyr structure, was formed in the (C)20 and (C)10GCG(C)10 inserts in plasmids in the presence of certain metal ions. Interestingly, H-r5, the other isomer of the Pur·Pur·Pyr triplex which had not been detected previously, was formed in a (C)9GAATT(C)9 insert in the presence of either Mg2+ or Ca2+. Alternatively, H-y3, one isomer of a Pyr·Pur·Pyr triplex, was formed in the (C)9GAATT(C)9 insert in the absence of metal ions. Thus, central non-Pur·Pyr sequences and metal ions play a role as determinants of the types of intramolecular triplexes formed; they also reduce the requirement of longer Pur·Pyr repeat sequences to form intramolecular triplexes. Furthermore, the effects of MgCl2 concentration and pH on the formation of triplex isomers were examined. The Pur·Pur·Pyr conformations (H-r3 and H-r5) may be the favored conformations in the cellular milieu, since they are stable at physiological pH and metal ion concentration.
UR - http://www.scopus.com/inward/record.url?scp=0026757199&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0026757199&partnerID=8YFLogxK
M3 - Article
VL - 267
SP - 20887
EP - 20891
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 29
ER -