TY - JOUR
T1 - Secondary structure in polyuridylic acid. Non-classical hydrogen bonding and the function of the ribose 2′-hydroxyl group
AU - Young, Peter R.
AU - Kallenbach, Neville R.
N1 - Funding Information:
One of us (P.R.Y.) acknowledges support as a National Research Service Award prc-doctoral trainee (PHS 5 T32 GM0 7229-03) during the later stages of this work. Nuclear magnetic resonance spectra were obtained at the Middle Atlantic NMR Facility, which 1s supported by National Institutes of Health grant RR542 at the University of Pennsylvania.
Funding Information:
We thank Dr Helen Berman and Dr S. W. Englander for many informative and Rong-Ine Ma for expert technical assistance. This work was support,ed Cancer Society grant NP187A.
PY - 1978/12/15
Y1 - 1978/12/15
N2 - The role of non-classical hydrogen bonding in RNA structure has been investigated using polyuridylic acid, which has a labile ordered structure at temperatures near 0 °C, as a model system. By comparing the proton nuclear magnetic resonance spectrum of poly(U) in the transition region with that of uridine and the dimer UpU we find evidence that both the imino N(3)-H and the ribosyl 2′-OH protons are hydrogen bonded. The characteristics of the former are consistent with participation in N(3)-HOC bonding primarily between residues in the same strand. As yet we cannot unambiguously assign the acceptor for the 2′-OH in ordered poly(U): because of its apparent stability and the acceptable stereochemistry, we presently favor a bond between ribose 2′-OH and O(1′) connecting adjacent nucleotides of the same strand. This arrangement could contribute to the co-operativity of the poly(U) helix formation. The recently proposed 2′-OHO(1′) interactions in crystalline yeast transfer RNAPhe suggest similar interactions might play a role in the conformational stability of natural RNAs. A second conformational transition below the major transition in the ultraviolet can be detected in poly(U) by monitoring the H(6) proton of uracil.
AB - The role of non-classical hydrogen bonding in RNA structure has been investigated using polyuridylic acid, which has a labile ordered structure at temperatures near 0 °C, as a model system. By comparing the proton nuclear magnetic resonance spectrum of poly(U) in the transition region with that of uridine and the dimer UpU we find evidence that both the imino N(3)-H and the ribosyl 2′-OH protons are hydrogen bonded. The characteristics of the former are consistent with participation in N(3)-HOC bonding primarily between residues in the same strand. As yet we cannot unambiguously assign the acceptor for the 2′-OH in ordered poly(U): because of its apparent stability and the acceptable stereochemistry, we presently favor a bond between ribose 2′-OH and O(1′) connecting adjacent nucleotides of the same strand. This arrangement could contribute to the co-operativity of the poly(U) helix formation. The recently proposed 2′-OHO(1′) interactions in crystalline yeast transfer RNAPhe suggest similar interactions might play a role in the conformational stability of natural RNAs. A second conformational transition below the major transition in the ultraviolet can be detected in poly(U) by monitoring the H(6) proton of uracil.
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U2 - 10.1016/0022-2836(78)90053-0
DO - 10.1016/0022-2836(78)90053-0
M3 - Article
C2 - 745237
AN - SCOPUS:0018270081
SN - 0022-2836
VL - 126
SP - 467
EP - 479
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 3
ER -