当前位置： SCI文献检索 > BIOCHEMISTRY期刊下所有文献 > Small Molecule Rescue and Glycosidic Conformational Analysis of the Twister Ribozyme.

Small Molecule Rescue and Glycosidic Conformational Analysis of the Twister Ribozyme.

Abstract：

:The number of self-cleaving ribozymes has increased sharply in recent years, giving rise to elaborations of the four known ribozyme catalytic strategies, α, β, γ, and δ. One such extension is utilized by the twister ribozyme, which is hypothesized to conduct δ, or general acid catalysis, via N3 of the syn adenine +1 nucleobase indirectly via buffer catalysis at biological pH and directly at lower pH. Herein, we test the δ catalysis role of A1 via chemical rescue and the catalytic relevance of the syn orientation of the nucleobase by conformational analysis. Using inhibited twister ribozyme variants with A1(N3) deaza or A1 abasic modifications, we observe >100-fold chemical rescue effects in the presence of protonatable biological small molecules such as imidazole and histidine, similar to observed rescue values previously reported for C75U/C76Δ in the HDV ribozyme. Brønsted plots for the twister variants support a model in which small molecules rescue catalytic activity via a proton transfer mechanism, suggesting that A1 in the wild type is involved in proton transfer, most likely general acid catalysis. Additionally, through glycosidic conformational analysis in an appropriate background that accommodates the bromine atom, we observe that an 8BrA1-modified twister ribozyme is up to 10-fold faster than a nonmodified A1 ribozyme, supporting crystallographic data that show that A1 is syn when conducting proton transfer. Overall, this study provides functional evidence that the nucleotide immediately downstream of the cleavage site participates directly or indirectly in general acid-base catalysis in the twister ribozyme while occupying the syn conformation.

journal_name

Biochemistry

journal_title

Biochemistry

authors

Messina KJ,Kierzek R,Tracey MA,Bevilacqua PC

doi

10.1021/acs.biochem.9b00742

subject

Has Abstract

pub_date

2019-12-03 00:00:00

pages

4857-4868

issue

48

eissn

0006-2960

issn

1520-4995

journal_volume

58

pub_type

杂志文章

相关文献

BIOCHEMISTRY文献大全