1C95

Solution structure of the aminoacyl-capped oligodeoxyribonucleotide duplex TRP-D(TGCGCAC)2

1C95 の概要

• エントリーDOI: 10.2210/pdb1c95/pdb
• 分子名称: 5'-D((5AT)TP*GP*CP*GP*CP*AP*C)-3', TRYPTOPHAN (2 entities in total)
• 機能のキーワード: double helix, aminoacyl-capped dna, dna
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 4443.32

構造登録者

Ho, W.C.,Steinbeck, C.,Richert, C. (登録日: 1999-07-31, 公開日: 1999-10-08, 最終更新日: 2024-05-22)

主引用文献

Ho, W.C.,Steinbeck, C.,Richert, C.
Solution structure of the aminoacyl-capped oligodeoxyribonucleotide duplex (W-TGCGCAC)(2).
Biochemistry, 38:12597-12606, 1999

PubMed Abstract: Reported here is the solution structure of the aminoacyl-DNA duplex (W-TGCGCAC)(2). This duplex forms a continuously pi-stacked helix consisting of both nucleobases and amino acid side chains. According to NMR and UV analyses, the duplex melts in a cooperative transition and with 1.3-1.8% greater hyperchromicity than the control duplex (TGCGCAC)(2). A van't Hoff analysis of UV melting points at different concentrations shows that the two tryptophan residues contribute 4.8 kcal/mol to the DeltaH degrees of complex formation at 10 mM salt concentration and less than 1 kcal/mol at 150 mM salt. The entropic cost for duplex association in the presence of the amino acid residues is 13 cal/molK greater than that for the control at 10 mM salt concentration, and 3 cal/molK lower than that of the control at 0.15 ionic strength. The conformation of W-TGCGCAC in duplex form, determined via restrained torsion angle molecular dynamics, shows an undisturbed B-form DNA duplex with dangling 3'-termini. The tryptophanyl residue at the 5'-terminus packs tightly against T2 and the proximal part of adenine, without engaging in hydrogen bonding. While not providing strong enthalpic net stabilization of the duplex, the tryptophan "cap" on the duplex does seem to reduce the fraying at the termini, indicating a subtle balance of entropic and enthalpic factors contributing to the molecular dynamics. The structure also shows that, at least in the present sequence context, stacking on the terminal base pair is more favorable than intercalation, probably because the enthalpic cost associated with breaking up the stacking between DNA base pairs cannot be paid for by favorable pi-stacking interactions with the indole ring of tryptophan. These results are of importance for understanding stacking interactions in protein-DNA complexes, particularly those in enzyme-substrate complexes involving exposed nucleobases.

PubMed: 10504228
DOI: 10.1021/bi991169w

実験手法

SOLUTION NMR