Question

There are several eukaryotic species (for example, Tetrahymena thermophila) known to contain introns that are capable of splicing themselves out of an RNA transcript without the assistance of any proteins. How would you go about proving that no proteins are required for these self-splicing introns to function correctly?

Answer 1

Tetrahymena thermophila is a unicellular, ciliated protozoa which is used as a model organism for molecular research.

RNA transcribed from eukaryotic genes undergoes processing to produce mature mRNA , needed for protein synthesis. This maturation involves splicing out of the introns as one of the steps such that the final mRNA comprises of the exons.

Splicing is catalyzed by small nuclear ribonucleoproteins. However, some RNAs, for instance in Tetrahymena, are able to undergo self-splicing.
They are examples of ribozymes as they have catalytic potential- just like the proteinaceous enzymes. The ability of RNA to show catalytic property is also suggestive of an RNA world- a hypothetical evolutionary stage in which self-replicating RNA originated before DNA and proteins.

According to me, if splicing is observed even after the incubation of the experimental system in the presence of proteases- enzymes that cleave and degrade proteins, it can be proven that proteins are not involved in the reaction of self-splicing.