PDBsum entry 2mnc

RNA

PDB id: 2mnc

Contents

DNA/RNA

PDB id:

2mnc

Name:

RNA

Title:

Oligonucleotide model of mir-21 pre-element

Structure:

RNA (5'- r( Gp Gp Gp Up Up Gp Ap Cp Cp Gp Up Up Gp Ap Ap Up Cp Up Cp Ap Cp Gp Gp Cp Ap Ap Cp Cp C)-3'). Chain: a. Engineered: yes. Other_details: mir-21_pre-element

Source:

Synthetic: yes

NMR struc:

14 models

Authors:

S.Chirayil,Q.Wu,C.Amezcua,K.Luebke

Key ref:

S.Chirayil et al. (2014). NMR characterization of an oligonucleotide model of the miR-21 pre-element. Plos One, 9, e108231. PubMed id: 25250627 DOI: 10.1371/journal.pone.0108231

Date:

02-Apr-14 Release date: 01-Oct-14

DNA/RNA chain

C-C-G-U-U-G-A-A-U-C-U-C-A-C-G-G 16 bases

DOI no: 10.1371/journal.pone.0108231

Plos One 9:e108231 (2014)

PubMed id: 25250627

NMR characterization of an oligonucleotide model of the miR-21 pre-element.

S.Chirayil, Q.Wu, C.Amezcua, K.J.Luebke.

ABSTRACT

We have used NMR spectroscopy to characterize an oligonucleotide stem loop structure based on the pre-element of an oncogenic microRNA, miR-21. This predicted stem-loop structure is cleaved from the precursor of miR-21 (pre-miR-21) by the nuclease Dicer. It is also a critical feature recognized by the protein complex that converts the primary transcript (pri-miR-21) into the pre-miRNA. The secondary structure of the native sequence is poorly defined by NMR due to rapid exchange of imino protons with solvent; however, replacement of two adjacent putative G•U base pairs with G•C base pairs retains the conformation of the hairpin observed by chemical probing and stabilizes it sufficiently to observe most of the imino proton resonances of the molecule. The observed resonances are consistent with the predicted secondary structure. In addition, a peak due to a loop uridine suggests an interaction between it and a bulged uridine in the stem. Assignment of non-exchangeable proton resonances and characterization of NOEs and coupling constants allows inference of the following features of the structure: extrahelicity of a bulged adenosine, deviation from A-form geometry in a base-paired stem, and consecutive stacking of the adenosines in the 5' side of the loop, the guanosine of the closing base pair, and a cross-strand adenosine. Modeling of the structure by restrained molecular dynamics suggests a basis for the interaction between the loop uridine, the bulged uridine in the stem, and an A•U base pair in the stem.