TY - JOUR
T1 - The structure of an RNA/DNA hybrid
T2 - A substrate of the ribonuclease activity of HIV-1 reverse transcriptase
AU - Horton, Nancy C.
AU - Finzel, Barry C.
PY - 1996/12/6
Y1 - 1996/12/6
N2 - The structure of a complementary hybrid duplex of RNA and DNA has been determined by X-ray crystallography. A ten residue DNA oligonucleotide of sequence 5'-G-G-C-G-C-C-C-G-A-A-3' was annealed to complementary RNA (5'-u-u-c-g-g-g-c-g-c-c-3') and crystallized, producing tetragonal crystals that diffract to 2.3 Å resolution. The hybrid adopts a geometry that is neither strictly A nor B-form, rather the helix possesses qualities of both, reminiscent of spectroscopic descriptions of a hybrid conformation, or H-form. All of the ribonucleotides maintain the C3'-endo conformation seen in A-form, while both CS'-endo and C2'-endo conformations are found in the deoxyribonucleotides. The minor groove width (8.5 to 10.5 Å) is intermediate between standard values for A (11 Å) and B-form (7.4 Å) DNA. The global parameters rise and base-pairs tilt (or inclination) are like that of A-DNA, however the slide and x: displacement (Dx) are more like that of A-RNA, thus giving the hybrid a unique conformation. In addition, the 10-mer crystallizes in a manner that allows the formation of dimers that stack end-to-end, thereby providing a glimpse of how an extended (20 base-pair) helix of RNA-DNA hybrid might appear. This duplex sequence was selected for study because it is specifically recognized by the ribonuclease H function of HIV reverse transcriptase. A structure of a substrate of this enzyme is of potential value in understanding requirements for the selectivity of this important drug target. The minor groove of the hybrid duplex, lined with the 2-OH of the ribose rings, is the single distinguishing characteristic of the RNA/DNA hybrid, undoubtedly an important structural feature conferring selectivity.
AB - The structure of a complementary hybrid duplex of RNA and DNA has been determined by X-ray crystallography. A ten residue DNA oligonucleotide of sequence 5'-G-G-C-G-C-C-C-G-A-A-3' was annealed to complementary RNA (5'-u-u-c-g-g-g-c-g-c-c-3') and crystallized, producing tetragonal crystals that diffract to 2.3 Å resolution. The hybrid adopts a geometry that is neither strictly A nor B-form, rather the helix possesses qualities of both, reminiscent of spectroscopic descriptions of a hybrid conformation, or H-form. All of the ribonucleotides maintain the C3'-endo conformation seen in A-form, while both CS'-endo and C2'-endo conformations are found in the deoxyribonucleotides. The minor groove width (8.5 to 10.5 Å) is intermediate between standard values for A (11 Å) and B-form (7.4 Å) DNA. The global parameters rise and base-pairs tilt (or inclination) are like that of A-DNA, however the slide and x: displacement (Dx) are more like that of A-RNA, thus giving the hybrid a unique conformation. In addition, the 10-mer crystallizes in a manner that allows the formation of dimers that stack end-to-end, thereby providing a glimpse of how an extended (20 base-pair) helix of RNA-DNA hybrid might appear. This duplex sequence was selected for study because it is specifically recognized by the ribonuclease H function of HIV reverse transcriptase. A structure of a substrate of this enzyme is of potential value in understanding requirements for the selectivity of this important drug target. The minor groove of the hybrid duplex, lined with the 2-OH of the ribose rings, is the single distinguishing characteristic of the RNA/DNA hybrid, undoubtedly an important structural feature conferring selectivity.
KW - Drug target
KW - HIV reverse transcriptase
KW - RNA/DNA hybrid
KW - RNase H
KW - X-ray structure
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U2 - 10.1006/jmbi.1996.0658
DO - 10.1006/jmbi.1996.0658
M3 - Article
C2 - 8969302
AN - SCOPUS:0030572981
SN - 0022-2836
VL - 264
SP - 521
EP - 533
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 3
ER -