Related Experiment Video

Updated: May 14, 2026

Sample Preparation for Mass Spectrometry-based Identification of RNA-binding Regions
10:52

Sample Preparation for Mass Spectrometry-based Identification of RNA-binding Regions

Published on: September 28, 2017

Structure of the Cmr2-Cmr3 subcomplex of the Cmr RNA silencing complex

Yaming Shao1, Alexis I Cocozaki, Nancy F Ramia

  • 1Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA.

Structure (London, England : 1993)
|February 12, 2013
PubMed

Insights

Researchers elucidated the crystal structure of a CRISPR-associated (Cas) Cmr subcomplex, revealing key interactions between Cmr2 and Cmr3 subunits. This structural insight aids understanding of prokaryotic RNA-guided immunity mechanisms.

Area of Science:

  • Molecular Biology
  • Structural Biology
  • Microbiology

Background:

  • The CRISPR-Cas system provides adaptive immunity in prokaryotes by targeting and cleaving foreign nucleic acids.
  • The Cmr complex is a key RNA-guided effector complex within the CRISPR-Cas system, responsible for degrading invading RNA.
  • Understanding the structural basis of Cmr complex function is crucial for elucidating prokaryotic defense mechanisms.

Purpose of the Study:

  • To determine the crystal structure of a Cmr subcomplex composed of Cmr2 (Cas10) and Cmr3 subunits.
  • To investigate the molecular interactions between Cmr2 and Cmr3 subunits.
  • To identify regions within Cmr3 involved in Cmr complex assembly and RNA cleavage activity.

Main Methods:

  • X-ray crystallography was employed to obtain the 2.8 Å resolution structure of the Cmr2-Cmr3 subcomplex.
  • Site-directed mutagenesis was used to probe the function of specific Cmr3 domains and loops.
  • Analysis of RNA cleavage activity was performed to assess the functional impact of mutations.

Main Results:

  • The crystal structure revealed a dual ferredoxin fold and glycine-rich loops in Cmr3, alongside two unique insertion elements mediating Cmr2 interaction.
  • Mutations in Cmr3 insertion elements weakened the Cmr2-Cmr3 interaction but had differential effects on RNA cleavage, suggesting roles for other subunits.
  • Mutational analysis of conserved glycine-rich loops in Cmr3 identified a region potentially involved in Cmr complex assembly or RNA cleavage.

Conclusions:

  • The structure provides a detailed molecular basis for Cmr2-Cmr3 interactions within the Cmr complex.
  • The findings highlight the complex interplay of subunits in regulating Cmr complex function and RNA cleavage.
  • This study identifies novel functional regions in Cmr3, advancing our understanding of CRISPR-Cas RNA-guided immunity.

More Related Videos

MS2-Affinity Purification Coupled with RNA Sequencing in Gram-Positive Bacteria08:34

MS2-Affinity Purification Coupled with RNA Sequencing in Gram-Positive Bacteria

Published on: February 23, 2021

RNA-Associated Chromatin DNA-DNA Interaction Method11:01

RNA-Associated Chromatin DNA-DNA Interaction Method

Published on: April 30, 2026

Related Concept Videos

siRNA - Small Interfering RNAs02:30

siRNA - Small Interfering RNAs

Small interfering RNAs, or siRNAs, are short regulatory RNA molecules that can silence genes post-transcriptionally, as well as the transcriptional level in some cases. siRNAs are important for protecting cells against viral infections and silencing transposable genetic elements.
In the cytoplasm, siRNA is processed from a double-stranded RNA, which comes from either endogenous DNA transcription or exogenous sources like a virus. This double-stranded RNA is then cleaved by the ATP-dependent...
Cis-regulatory Sequences02:02

Cis-regulatory Sequences

Cis-regulatory sequences are short fragments of non-coding DNA that are present on the same chromosomes as the genes that they regulate. These fragments serve as binding sites for transcriptional regulators, proteins that are responsible for controlling gene transcription and differential gene expression across cell types in eukaryotes. Cis-regulatory sequences can be close to the gene of interest or thousands of bases away in the DNA sequence; however, those sequences that are further away are...
Cis-regulatory Sequences02:02

Cis-regulatory Sequences

Cis-regulatory sequences are short fragments of non-coding DNA that are present on the same chromosomes as the genes that they regulate. These fragments serve as binding sites for transcriptional regulators, proteins that are responsible for controlling gene transcription and differential gene expression across cell types in eukaryotes. Cis-regulatory sequences can be close to the gene of interest or thousands of bases away in the DNA sequence; however, those sequences that are further away are...
Experimental RNAi02:15

Experimental RNAi

RNA interference (RNAi) is a cellular mechanism that inhibits gene expression by suppressing its transcription or activating the RNA degradation process. The mechanism was discovered by Andrew Fire and Craig Mello in 1998 in plants. Today, it is observed in almost all eukaryotes, including protozoa, flies, nematodes, insects, parasites, and mammals. This precise cellular mechanism of gene silencing has been developed into a technique that provides an efficient way to identify and determine the...
Cooperative Binding of Transcription Regulators02:13

Cooperative Binding of Transcription Regulators

Transcriptional regulators bind to specific cis-regulatory sequences in the DNA to regulate gene transcription. These cis-regulatory sequences are very short, usually less than ten nucleotide pairs in length. The short length means that there is a high probability of the exact same sequence randomly occurring throughout the genome.  Since regulators can also bind to groups of similar sequences, this further increases the chances of random binding. Transcriptional regulators form dimers that...
RNA Interference01:23

RNA Interference

RNA interference (RNAi) is a process in which a small non-coding RNA molecule blocks the post-transcriptional expression of a gene by binding to its messenger RNA (mRNA) and preventing the protein from being translated.
This process occurs naturally in cells, often through the activity of genomically-encoded microRNAs. Researchers can take advantage of this mechanism by introducing synthetic RNAs to deactivate specific genes for research or therapeutic purposes. For example, RNAi could be used...