Remember learning that ribosomes are made of 1 large subunit RNA + 1 small subunit RNA? Well, some cells defy this rule, and the most extreme case is Toxoplasma which makes its mitoribosome from >50 RNA pieces! Wanna know how? Read below - ThreadSky

sheinerlab.bsky.social • 39 days ago

Remember learning that ribosomes are made of 1 large subunit RNA + 1 small subunit RNA?
Well, some cells defy this rule, and the most extreme case is Toxoplasma which makes its mitoribosome from >50 RNA pieces!
Wanna know how? Read below

Comments

painterlab.bsky.social•38 days ago

Beautiful work! Congratulations!

apicolipid.bsky.social•39 days ago

Congrats, superb work and paper!!

sheinerlab.bsky.social•39 days ago

In conclusion, the #Toxoplasma #mitoribosome provides an extreme example for the evolutionary malleability of #rRNA and ribosomes and reveals novel insights in RNA and #ribosome biology.

https://www.nature.com/articles/s41467-025-56057-9

All data files can find here for mining: https://doi.org/10.6084/m9.figshare.26299624

joana-santos.bsky.social•39 days ago

Wow!! Congratulations!

sheinerlab.bsky.social•39 days ago

Another interesting observation for the #Toxoplasma aficionados. The #mitochondrial #genome is made of repeating blocks of sequences. We found rRNAs that are translated only from adjacent blocks. Namely the ribosome might “dictate” block order.

sheinerlab.bsky.social•39 days ago

One of the apiAP2 members, mL161 in our structure, was repurposed to “fill in” for a reduced helix h44 critical for subunit interface. Here mL161 extends an N-terminal domain embedded in the LSU, and a C-terminal extension that penetrates the SSU.

sheinerlab.bsky.social•39 days ago

Proteins with transcription factor folds were recruited to replace reduced mitoribosome domains. Particularly interesting for apicomplexan research is the repurposing of four apiAP2 family members to support the mitoribosome function. As recently reported here too:
https://www.nature.com/articles/s41467-024-55033-z

sheinerlab.bsky.social•39 days ago

Our observations include insights that have been reported for ribosome in the past, such as the involvement of RNA binding proteins in supporting stability, and the repurposing of proteins with known functional domain as ribosomal proteins. Some examples in the next comments.

sheinerlab.bsky.social•39 days ago

The addition of PolyA “handles” and the re-use of rRNA sequences provide new examples of how mitochondrial genomes can become reduced while mitoribosomes can remain functional.

sheinerlab.bsky.social•39 days ago

3. In all ribosomes studied till now rRNA sequences making up the ribosome are unique. Here, the same RNA sequences are “re-used” – they appear twice in the ribosome, each time taking a different fold.

sheinerlab.bsky.social•39 days ago

2. Poly adenine (polyA) tails are known as stabilisers of messenger RNAs. But here polyA tails are added to ribosomal RNAs where they serve as “handles” that mediate ribosome piecing together (red in the movie above and pic here).

sheinerlab.bsky.social•39 days ago

1. While ribosomes with several RNA pieces were seen before, typically each RNA molecule is long enough to self-fold into its functional form. But here RNAs as short as 7nt cannot self-fold thus are fully dependent on proteins to become functional – not really an “RNA machine” anymore.

sheinerlab.bsky.social•39 days ago

Three features that are new to ribosome biology were found in the unusually fragmented Toxoplasma mitoribosome:

sheinerlab.bsky.social•39 days ago

Our structure-function analysis of the Toxoplasma mitoribosome reveals a novel role for poly A tails and repurposed protein domains in mending tens of rRNA pieces into a functioning ribosome

https://www.nature.com/articles/s41467-025-56057-9
@shikhas.bsky.social @uofgmvls.bsky.social

abhinay.bsky.social•38 days ago

Lots of spaghetti to dig in.. congrats @shikhas.bsky.social @sheinerlab.bsky.social et al!

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