Single-Molecule Analysis on the Folding Mechanism of Human Telomerase RNA Pseudoknot Structure
Date Issued
2014
Date
2014
Author(s)
Chen, Yu-Ting
Abstract
Human telomerase is composed of a 451 nt RNA (hTR) and several proteins, including a specialized reverse transcriptase (hTERT). The 5’ domain of hTR contains a RNA template for telomere synthesis and a highly conserved pseudoknot structure crucial for telomerase activity.
The highly conserved pseudoknot structure has two hairpin (stem-loop) structures. The interaction of two hairpin structures formed a major-groove and a minor-groove, as well as five triple-base pairs between them. Previous experiments have shown that the stability of the pseudokont derived from hTR (hTR DU177) was related to the base triples. However, the mechanism of pseudoknot folding is not well understood.
In this study, we used optical tweezers to measure the unfolding force of a series of hTR DU177-related structures and analyzed the relationship between the force and the extension. Instead of being completely unfolded in one step, we found that only one of the two hairpins within the pseudoknot was formed and unfolded during most of the recordings. Based on further experiments, we propose that the pseudoknot is formed by two alternative pathways: Formation of the two hairpin structures kinetically competes to each other. DU177 often tends to form the stable hairpin 1 rapidly, but proceeds to fold into the complete pseudoknot in a much slower fashion. On the other hand, the RNA occasionally folds into an intact pseudoknot structure quickly via the less preferred hairpin 2 pathway.
Subjects
偽結結構
髮夾結構
三重鹼基對
雷射光鉗
單分子
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-103-R01b43017-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):2cf93454847f4288ce96b90b3934b2be