Nonstandard RNA/RNA interactions likely enhance folding and stability of segmented ribosomes

The ribosome is the molecular factory that catalyzes all coded protein synthesis in extant organisms. Eukaryotic ribosomes are typically assembled out of four rRNAs; namely, 5S, 5.8S, 18S, and 28S. However, the 28S rRNA of some trypanosomatid organisms has been found to be segmented into six indepen...

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Bibliographic Details
Published in:RNA (Cambridge) 2022-03, Vol.28 (3), p.340-352
Main Authors: Rivas, Mario, Fox, George E
Format: Article
Language:English
Subjects:
Hydrogen bonding
Leishmania donovani - genetics
Leishmania donovani - metabolism
Nucleotide sequence
Protein biosynthesis
Protozoa
Replicase
Ribosomes
Ribosomes - chemistry
Ribosomes - metabolism
RNA Folding
RNA Stability
RNA, Ribosomal - chemistry
RNA, Ribosomal - metabolism
RNA-directed RNA polymerase
rRNA 28S
Trypanosoma brucei brucei - genetics
Trypanosoma brucei brucei - metabolism
Trypanosoma cruzi - genetics
Trypanosoma cruzi - metabolism
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Summary:The ribosome is the molecular factory that catalyzes all coded protein synthesis in extant organisms. Eukaryotic ribosomes are typically assembled out of four rRNAs; namely, 5S, 5.8S, 18S, and 28S. However, the 28S rRNA of some trypanosomatid organisms has been found to be segmented into six independent rRNAs of different sizes. The two largest segments have multiple sites where they jointly form stems comprised of standard base pairs that can hold them together. However, such regions of interaction are not observed among the four smaller RNAs. Early reports suggested that trypanosomatid segmented ribosome assembly was essentially achieved thanks to their association with rProteins. However, examination of cryo-EM ribosomal structures from , , and reveals several long-range nonstandard RNA/RNA interactions. Most of these interactions are clusters of individual hydrogen bonds and so are not readily predictable. However, taken as a whole, they represent significant stabilizing energy that likely facilitates rRNA assembly and the overall stability of the segmented ribosomes. In the context of origin of life studies, the current results provide a better understanding of the true nature of RNA sequence space and what might be possible without an RNA replicase.
ISSN:1355-8382
1469-9001
DOI:10.1261/rna.079006.121