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A model for RNA editing in kinetoplastid mitochondria: "guide" RNA molecules transcribed from maxicircle DNA provide

B Blum1, N Bakalara, L Simpson

  • 1Department of Biology, University of California, Los Angeles 90024.

Cell
|January 26, 1990
PubMed

Insights

Small RNA molecules, termed guide RNAs (gRNAs), in Leishmania tarentolae mitochondria may orchestrate RNA editing. These gRNAs guide precise mRNA modifications through hybrid formation and a proposed editing cycle.

Area of Science:

  • Molecular Biology
  • Genetics
  • Parasitology

Background:

  • Mitochondrial RNA editing is crucial for gene expression in some organisms.
  • Leishmania tarentolae exhibits extensive RNA editing in its mitochondrial transcripts.

Purpose of the Study:

  • To investigate the role of small RNA molecules in Leishmania tarentolae mitochondrial RNA editing.
  • To elucidate the mechanism by which these small RNAs facilitate mRNA maturation.

Main Methods:

  • Analysis of mitochondrial DNA sequences encoding small RNAs.
  • Comparison of small RNA sequences with pre-edited and mature mRNA sequences.
  • Modeling of RNA-RNA interactions and editing processes.

Main Results:

  • A class of small RNAs (guide RNAs) was identified in Leishmania tarentolae mitochondria.
  • gRNAs possess sequences complementary to edited regions of mature mRNAs.
  • gRNAs can form partial hybrids with pre-edited mRNAs upstream of the edited sites.

Conclusions:

  • gRNAs are likely involved in guiding mitochondrial RNA editing in Leishmania.
  • A model proposes gRNA-mRNA hybridization initiates a cycle of cleavage, uridylate addition/deletion, and religation for editing.
  • This mechanism explains the precise sequence complementarity between gRNAs and mature mRNAs.

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Transcription01:10

Transcription

Overview
Transcription is the process of synthesizing RNA from a DNA sequence by RNA polymerase. It is the first step in producing a protein from a gene sequence. Additionally, many other proteins and regulatory sequences are involved in the proper synthesis of messenger RNA (mRNA). Regulation of transcription is responsible for the differentiation of all the different types of cells and often for the proper cellular response to environmental signals.
Transcription Can Produce Different Kinds...
Types of RNA01:23

Types of RNA

Overview
Three main types of RNA are involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). These RNAs perform diverse functions and can be broadly classified as protein-coding or non-coding RNA. Non-coding RNAs play important roles in the regulation of gene expression in response to developmental and environmental changes. Non-coding RNAs in prokaryotes can be manipulated to develop more effective antibacterial drugs for human or animal use.
RNA...
RNA Editing02:23

RNA Editing

RNA editing is a post-transcriptional modification where a precursor mRNA (pre-mRNA) nucleotide sequence is changed by base insertion, deletion, or modification. The extent of RNA editing varies from a few hundred bases, in mitochondrial DNA of trypanosomes, to a just single base, in nuclear genes of mammals. Even a single base change in the pre-mRNA can convert a codon for one amino acid into the codon for another amino acid or a stop codon. This type of re-coding can significantly affect the...
Types of RNA01:20

Types of RNA

Three main types of RNA are involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). These RNAs perform diverse functions and can be broadly classified as protein-coding or non-coding RNA. Non-coding RNAs play important roles in regulating gene expression in response to developmental and environmental changes. Non-coding RNAs in prokaryotes can be manipulated to develop more effective antibacterial drugs for human or animal use.
RNA Performs Diverse...
Transcription01:17

Transcription

Transcription is the synthesis of RNA from a DNA sequence by RNA polymerase. It is the first step in producing a protein from a gene sequence. Additionally, many other proteins and regulatory sequences are involved in correctly synthesizing messenger RNA (mRNA). Transcriptional regulation is responsible for the differentiation of different types of cells and often for the proper cellular response to environmental signals.
Transcription Can Produce Different Kinds of RNA Molecules
In eukaryotes,...
Nucleic Acid Structure01:25

Nucleic Acid Structure

The pentose sugar in DNA is deoxyribose, while in RNA the pentose sugar is ribose. The difference between the sugars is the presence of the hydroxyl group on the ribose's second carbon and a hydrogen on the deoxyribose's second carbon. The phosphate residue attaches to the hydroxyl group of the 5′ carbon of one sugar and the hydroxyl group of the 3′ carbon of the sugar of the next nucleotide, which forms  a 5′ to 3′ phosphodiester linkage.
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DNA has a double-helix structure. The...