RNA Editing Flashcards
RNA editing targets ___ and ____ RNA
Coding, non-coding
RNA editing changes primary sequence of some RNA post __________
Transcriptionally
Purpose of RNA editing?
Regulating gene expression, increases proteome complexity, protects genome against some viruses
Two main types of RNA editing mechanisms:
1) Substitution editing 2) Insertion/deletion editing
Substitution editing examples:
1) Cytidine -> Uridine (C-U) 2) Adenosine -> Inosine (A-U) 3) Deamination 4) Base modifications that change chemistry of nucleotides
Insertion/deletion editing examples:
Cytidine, uridine, adenine nucleotides
Insertion/deletion editing organisms?
Slime mold (C), vertebrate (A), trypanosome (U)
Substitution editing organisms?
Animals (A-I), mammals (C-U), plant organelles (C-U)
Amino group removed from adenosine (deamination) happens in _____
A-I substitution editing
ADAR
Adenine deaminase in A-I editing
How does ADAR act?
Binds and modified dsRNA, interacts with minor shallow groove, low seq specificity
Biological function of A-I editing?
Controls activity of human Alu-elements, modifies ORFs of transcribed mRNAs, changes intron splicing signals, nuclear retention of some mRNAs (infection response)
______ are main targets of A-I editing in humans
Alu-elements (90% of human A-I editing)
Alu editing reduces dsRNA ___________
Structure regions
A-I editing mouse brain
Glutamine receptor GluR2 subunit, neurotransmitter, no editing leads to learning and memory defects
Why are squids and octopuses smart?
Extensive A-I editing, 57,000 editing sites in brain mRNAs
A-I editing tRNA (transfer)
More widespread than mRNA mods, enables it to read more than one codon, ADAT
What is C-U editing?
Amino acid removed from cytosine (in mammals only in intestine)
C-U editing ApoB protein
ApoB important role in transport of cholesterol and lipids, intestinal edited form lacks C-domain
ApoBec and ADAR evolutionary linked?
No, but similar
ApoBec and ADAR depend on ________ as guide for editing
Hairpin structure
C-U editing plant organelles (some U-C)
ctDNA and mtDNA, post-transcriptional, deamination but unknown mechanism
A-insertion editing in ________
Vertebrate mitochondria mRNAs
mRNA/rRNA/tRNA C-insertion editing in _______
Mitochondria of molds
U-insertions in _______
Trypanosome mitochondria
guide RNA-based editing in _______
Trypanosome mitochondria
gRNA-based editing
3’ to 5’ direction, post-transcriptional, catalyzed by editosome (enzyme complex), HEAVILY edits genes
U insertion/deletion editing is RNA _______
Repair mechanism
