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Comparison of solution conformations and stabilities of modified helix 69 rRNA analogs from bacteria and human
Author(s) -
Sumita Minako,
Jiang Jun,
SantaLucia John,
Chow Christine S.
Publication year - 2012
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.21706
Subject(s) - ribosomal rna , rna , pseudouridine , circular dichroism , nucleotide , ribosome , chemistry , protein secondary structure , nucleic acid structure , biochemistry , 5.8s ribosomal rna , uridine , crystallography , gene
The helix 69 (H69) region of the large subunit (28S) ribosomal RNA (rRNA) of Homo sapiens contains five pseudouridine (Ψ) residues out of 19 total nucleotides, three of which are highly conserved. In this study, the effects of this abundant modified nucleotide on the structure and stability of H69 were compared with those of uridine in double‐stranded (stem) regions. These results were compared with previous hairpin (stem plus single‐stranded loop) studies to understand the contributions of the loop sequences to H69 structure and stability. The role of a loop nucleotide substitution from an A in bacteria (position 1918 in Escherichia coli 23S rRNA) to a G in eukaryotes (position 3734 in H. sapiens 28S rRNA) was examined. Thermodynamic parameters for the duplex RNAs were obtained through UV melting studies, and differences in the modified and unmodified RNA structures were examined by circular dichroism spectroscopy. The overall folded structure of human H69 appears to be similar to the bacterial RNA, consistent with the idea that ribosome structure and function are highly conserved; however, our results reveal subtle differences in structure and stability between the bacterial and human H69 RNAs in both the stem and loop regions. These findings may be significant with respect to H69 as a potential drug target site. © 2011 Wiley Periodicals, Inc. Biopolymers 97: 94–106, 2012.