lf206 lecture 7 - eukaryotic genomes, post transcriptional control II

RNA occurs in all 3 _____ (eukaryotic tRNA, rRNA, mRNA, miRNA, archaea, bacteria)

in ________ there is extensive RNA editing of some kinetoplast genes (what are these?)

in vertebrate RNA editing occurs in the _______

domains

trypanosomes, genes of Kinetoplastida (flagellated protists)

nucleus

the structure of DNA in Trypansoma brucei

mitochondrial DNA is kDNA (k stands for what?)

it is found in the kinetoplast, which is in the _______ mitochondrion of the protozoa

has a mixture of _______ (~~23kb, copy number ~50) and a heterogeneous set (what does this mean?) of minicircles (~1kb, copy number ~______-_____)

they are ______/interlocked to form a planar _____ that resembles chain mail

kinetoplast

singular

maxicircles

each minicircle is not identical

5,000 - 10,000

catenated

network

maxicircle kDNA encodes two rRNAs (_S and _S), one ribosomal protein (_____) and ___ protein-coding sequences

12 of the ORFs (what are they?) require RNA _____ in order to be converted into translatable ____

9S

12S

RPS12

17

open reading frame (stretches of DNA that could be translated to a protein - we’re unsure if the cell actually uses them)

editing

mRNA

what is RNA editing

editing RNA after it has been transcribed

some maxicircle mRNA is extensively edited as some the genes are ______ and their transcripts must be decrypted by RNA ______ prior to translation

RNA editing creates ____ _______ _____

encrypted

editing

open reading frames

base addition and deletion in _________ maxicircles:

1. ____ ___ (gRNA1) encoded by a ___circle binds the target RNA by base pairing at its 5’ anchor and 3’ ___ sequences

2. gRNA1 provides a ______ that can be copied into the final edited mRNA

3. _____ is encoded on a different minicircle and the so on…

trypanosomes

guide RNA

minicircle

tail

template

gRNA2

what is speculated about why mitochondria of trypanosomes and plants utilise such extensive RNA editing?

a primitive genetic system offering few options for other forms of transcriptional control

cytosine can be ________ to generate uracil.

can alter ______

deaminated

protein sequences and therefore alter protein function

an editosome is a __S multiprotein containing enzymes (e.g. APOBEC) that catalyse RNA ______cycles.

what is APOBEC?

for cytidine to _____ editing, APOBEC forms a complex with ACF (______ _________ ______).

this complex recognises sequences ______ the C to be edited

20S

editing

ApoB mRNA editing enzyme catalytic subunit

uridine

APOBEC Complementation Factor

flanking