# TSEN34 ## Overview TSEN34 is a gene that encodes the tRNA splicing endonuclease subunit 34, a crucial component of the human tRNA splicing endonuclease complex. This protein is integral to the maturation of transfer RNA (tRNA) molecules, facilitating the precise excision of introns from precursor tRNA (pre-tRNA) to produce functional tRNA necessary for protein synthesis. Structurally, TSEN34 is characterized by distinct domains, including a nuclease fold that is essential for its endonuclease activity. It interacts with other subunits within the TSEN complex, such as TSEN15 and TSEN54, to form a stable and functional assembly. The catalytic activity of TSEN34 is mediated by a conserved triad of residues, which are critical for the cleavage of the 3′ splice site in pre-tRNA. Mutations in the TSEN34 gene have been linked to pontocerebellar hypoplasia, highlighting its importance in normal neuronal development and function (Hayne2022Recent; Sekulovski2022Structural; Yuan2023Recognition). ## Structure The TSEN34 protein is a subunit of the human tRNA splicing endonuclease complex, which is crucial for processing precursor tRNA molecules. TSEN34 is composed of 310 amino acids and features distinct structural domains. The N-terminal domain (NTD) of TSEN34 forms a barrel-like, 5-stranded β-sheet structure stabilized by a short α-helix, while the C-terminal domain contains a characteristic nuclease fold, consisting of a central, twisted, 5-stranded β-sheet sandwiched by two α-helices (Hayne2022Recent; Sekulovski2022Structural). TSEN34 interacts extensively with other subunits within the TSEN complex, particularly forming a heterodimer with TSEN15 through a hydrophobic interface mediated by the final C-terminal β-strand of each subunit (Hayne2022Recent). It also engages in intricate interactions with TSEN54, involving hydrogen bonds, salt bridges, and hydrophobic interactions, with a contact surface area of 2287.2 Ų (Sekulovski2022Structural). The protein contains a catalytic triad of residues Y247, H255, and K286, which are essential for its endonuclease activity, facilitating the cleavage of the 3′ splice site in pre-tRNA (Sekulovski2022Structural; Yuan2023Recognition). The structure of TSEN34, along with its interactions within the TSEN complex, highlights its role in the precise recognition and processing of pre-tRNA substrates. ## Function TSEN34 is a critical subunit of the human tRNA splicing endonuclease complex, which plays a vital role in the maturation of transfer RNA (tRNA) molecules. This complex is responsible for the precise excision of introns from precursor tRNA (pre-tRNA), a crucial step in tRNA processing that ensures the production of functional tRNA necessary for protein synthesis. TSEN34, along with TSEN2, forms a catalytic interface that recognizes and cleaves the 3′ splice site of the intron, contributing to the broader substrate specificity of the TSEN complex (Hayne2023Structural; Yuan2023Recognition). The catalytic activity of TSEN34 is facilitated by a conserved triad of residues—tyrosine (Y247), histidine (H255), and lysine (K286)—which are essential for the cleavage reaction. These residues are involved in stabilizing the conformation of the 3′ splice-site bulge, a key feature for effective splicing (Yuan2023Recognition). TSEN34 is active in the nucleus, where it ensures the accurate and efficient processing of tRNA, which is essential for cellular function and protein synthesis (Hayne2022Recent). The structural integrity and proper function of TSEN34 are crucial for maintaining the overall activity of the TSEN complex, impacting organismal outcomes such as brain development and function (Sekulovski2022Structural). ## Clinical Significance Mutations in the TSEN34 gene have been implicated in pontocerebellar hypoplasia, a severe neurodegenerative disorder. This condition is characterized by developmental delay, microcephaly, and cerebellar atrophy. The TSEN34 gene encodes a subunit of the tRNA splicing endonuclease complex, which is essential for proper tRNA processing. Alterations in TSEN34 can disrupt normal RNA processing, leading to cellular dysfunction and contributing to the pathogenesis of pontocerebellar hypoplasia. The disruption of tRNA processing due to TSEN34 mutations results in impaired protein synthesis, which is critical for normal neuronal development and function. This impairment is believed to underlie the neurodevelopmental defects observed in affected individuals. Understanding the role of TSEN34 in RNA processing and its impact on cellular function is crucial for developing potential therapeutic strategies for conditions associated with its mutations. ## Interactions TSEN34 is a critical component of the human tRNA splicing endonuclease complex, which includes TSEN2, TSEN15, and TSEN54. This complex is essential for the processing of pre-tRNA molecules. TSEN34 interacts extensively with TSEN54, forming a 'three-claw-clamp' conformation that stabilizes the complex. The interaction between TSEN34 and TSEN54 involves a significant buried surface area, facilitating the recognition and processing of pre-tRNA (Yuan2023Recognition). TSEN34 also forms an interface with TSEN15 through their C-terminal β-strands, contributing to the structural integrity of the complex (Hayne2023Structural). The TSEN34-TSEN54 interaction is characterized by hydrogen bonds, salt bridges, and hydrophobic interactions, which are crucial for the positioning of the mature domain of pre-tRNAs (Sekulovski2022Structural). In terms of nucleic acid interactions, TSEN34 plays a significant role in recognizing and binding to the pre-tRNA substrate. It interacts with the D-arm, elbow region, and 3′ bulge of the tRNA molecule, with specific residues such as R31 and K239 contributing to the recognition of the ribose-phosphate backbone (Yuan2023Recognition). The catalytic triad of TSEN34, consisting of Y247, H255, and K286, is essential for the cleavage mechanism at the 3′ splice site (Yuan2023Recognition). ## References [1. (Hayne2022Recent) Cassandra K. Hayne, Tanae A. Lewis, and Robin E. Stanley. Recent insights into the structure, function, and regulation of the eukaryotic transfer rna splicing endonuclease complex. WIREs RNA, February 2022. URL: http://dx.doi.org/10.1002/wrna.1717, doi:10.1002/wrna.1717. This article has 13 citations.](https://doi.org/10.1002/wrna.1717) [2. (Hayne2023Structural) Cassandra K. Hayne, Kevin John U. Butay, Zachary D. Stewart, Juno M. Krahn, Lalith Perera, Jason G. Williams, Robert M. Petrovitch, Leesa J. Deterding, A. Gregory Matera, Mario J. Borgnia, and Robin E. Stanley. Structural basis for pre-trna recognition and processing by the human trna splicing endonuclease complex. Nature Structural & Molecular Biology, 30(6):824–833, May 2023. URL: http://dx.doi.org/10.1038/s41594-023-00991-z, doi:10.1038/s41594-023-00991-z. This article has 17 citations.](https://doi.org/10.1038/s41594-023-00991-z) 3. (Sekulovski2022Structural) Structural basis of substrate recognition by human tRNA splicing endonuclease TSEN. This article has 2 citations. [4. (Yuan2023Recognition) Ling Yuan, Yaoyao Han, Jiazheng Zhao, Yixiao Zhang, and Yadong Sun. Recognition and cleavage mechanism of intron-containing pre-trna by human tsen endonuclease complex. Nature Communications, September 2023. URL: http://dx.doi.org/10.1038/s41467-023-41845-y, doi:10.1038/s41467-023-41845-y. This article has 5 citations and is from a highest quality peer-reviewed journal.](https://doi.org/10.1038/s41467-023-41845-y)