One of the most prevalent types of RNA in a cell is the transfer gene( tRNA ), which is essential for the production of proteins in all known organisms. They play a crucial role in” translation” by figuring out how the sequence of nucleic acids, which contains the genetic data, is transformed into the series of amino acids that make up proteins.
Pre-tRNAs, which are converted in a number of steps to become the mature, three-dimensionally arranged mRNA, are the source of transfer RNA. This includes a stage in some tRNAs where an intron, or specific section, is removed. The tRNA splicing endonuclease( TSEN ) in humans carries out this function.
The correct conversion of tRNAs is also ensured by the enzyme RNA kinase CLP1, which binds directly to TSEN. It appears that tRNAs can no longer form correctly if TSEN and CLP1 are unable to interact with one another due to a genetic mutation. This has a common impact on the emergence of neurodegenerative disorders. Pontocerebellar hypoplasia, which causes severe disabilities and early death in childhood, is one of these. The cerebellum and the pons, two parts of the brain stem, develop abnormally as a result of this extremely rare progressive disorder.
Although TSEN activity is necessary for survival, it is currently largely unknown how the enzyme binds pre-tRNAs and how introns are eliminated. It was also challenging to evaluate the changes brought on by particular pathogenic mutations due to the enzyme’s lack of a three-dimensional structure. Researchers led by Dr. Simon Trowitzsch from the Institute of Biochemistry at Goethe University have now been successful in shedding light on the three-dimensional structure of a TSEN / pre-tRNA complex by using cryo-electron microscopy ( cryo – EM ) performed at the facilities of the Julius-Maximulans University of WĆ¼rzburg and the institute of biochemistry in Frankfurt.
The research team was able to demonstrate for the first time how TSEN interacts with the L-shaped pre-tRNA using their cryo-EM reconstructions. TSEN then removes the intron from the L’s long arm.
TSEN first lands in the L’s corner, where it can then identify the short and long arms as well as the angle between them.
Dr. Simon Trowitzsch, Goethe University’s Institute of Biochemistry
The TSEN subunit 54 ( TSEN54 ) is crucial for pre-tRNA recognition, as the researchers have now been able to demonstrate. By using the subunit as a” molecular ruler” to measure the distance between the long and short arms of the L, TSEN can determine when the pre-tRNA needs to be cleaved in order to remove the intron.
It was surprising to learn new information about the interaction between the RNA kinase CLP1 and the TSEN subunit, which is known to bind to an unstructured and thereby highly flexible region of CSEN54. An amino acid that is most frequently mutated in patients with pontocerebellar hypoplasia is found in this area. According to Samoil Sekulovski, the study’s first author, this is a crucial sign that drug development in the future should focus on maintaining the interaction of TSEN and CLP1.
Now, the researchers are hoping that the structural information will enable them to create models that can be used to look for potential active substances. Trowitzsch sums up by saying,” While a promising therapy is still far away, our structure does lay the groundwork for an improved understanding of how TSEN functions and the disease patterns of its mutants.”