The human gene encoding tryptophanyl-tRNA synthetase: interferon-response elements and exon-intron organization

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Human tryptophanyl-tRNA synthetase (hWRS) is a housekeeping enzyme.
• hWRS is notably induced by interferons (IFN) gamma and alpha.
• The regulatory mechanisms governing hWRS gene expression, particularly its induction by IFNs, were previously unknown due to the absence of its genomic structure.

Purpose of the Study:

• To elucidate the exon-intron organization of the human tryptophanyl-tRNA synthetase (hWRS) gene.
• To identify potential regulatory elements involved in interferon-mediated induction of hWRS.
• To investigate the evolutionary conservation of hWRS structure.

Main Methods:

• Gene sequencing and analysis of exon-intron organization.
• Identification of regulatory sequences, including interferon-stimulating response elements (ISRE).
• Comparative amino acid sequence alignment with bacterial WRS.

Main Results:

• The hWRS gene comprises at least 12 exons spanning over 35 kb.
• Two alternative noncoding exons precede ten coding exons.
• Interferon-stimulating response elements (ISRE) were identified upstream of the first exon and within an intron, suggesting transcriptional regulation.
• Exons V-XI encode regions homologous to bacterial WRS, while the N-terminal portion (exons II-IV) shows no bacterial homology.

Conclusions:

• The interferon-stimulated synthesis of hWRS is likely mediated by gene activation at the transcriptional level.
• The identified ISRE sequences provide a molecular basis for IFN-induced hWRS expression.
• The structural divergence in the N-terminal region suggests unique functional roles for human WRS compared to its bacterial counterparts.