Exploring the structure and nucleic acid interactions of the Leishmania sp. telomerase reverse transcriptase N-terminal region

Author(s)

Paiva, Stephany C. ; Salvador, Guilherme Henrique Marchi ; Barbosa, Patrick S. ; de Oliveira, Hamine Cristina ; Fernandes, Carlos Alexandre H. ; Ramos, Carlos H. I. ; de M. Fontes, Marcos Roberto ; Cano, Maria Isabel N.

• Document type: Journal article
• Source: Archives of Biochemistry and Biophysics; v. 764, p. 15-pg., 2025-01-09.

Abstract

Leishmaniasis is a neglected tropical disease caused by protozoans of the Leishmania genus, against which no effective treatment or control is available. Like other eukaryotes, parasite telomeres are maintained by telomerase, a ribonucleoprotein complex vital for genome stability. Its protein component, TERT (telomerase reverse transcriptase), presents four structural and functional domains, with the TEN (Telomerase N-terminal) and TRBD (Telomerase RNA-binding) located at its N-terminal. The enzyme also contains an RNA component that carries the template copied by the TERT during telomere elongation. Here, we show that the tertiary structure of Leishmania major TERT (LmTERT) is conserved compared to other eukaryotes. However, the LmTERT N-terminal (LmTERT-NT) portion shows structural changes not detected in the entire protein, mainly in the TEN domain. Besides the disordered elements, the TEN gains two long beta-sheets but preserves the GQ motif and the residues in beta-sheet 5 that interact with the TRAP motif. In both structures, a linker flanks the TEN and TRBD. The TRBD is partially conserved in both structures and contains the canonical QFP and T motifs, invariant residues, and the putative CP and two trypanosomatid-specific motifs (TSM) besides genus-specific amino acid substitutions. Despite the structural changes, the recombinant LmTERT-NT preserves a hydrophobic cavity that binds specifically and in the picomolar range to the telomeric G-rich DNA and the TER 5 ' end region. Thus, LmTERT-NT shares the canonical structural domains and motifs and is biochemically active. We discuss the importance of the TERT N-terminal region in the parasite's telomerase catalysis. (AU)

• FAPESP's process: 19/05958-4 - Multi-User Equipment approved in grant 2013/24705-3: high pressure liquid chromatography system
• Grantee: Marcos Roberto de Mattos Fontes
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 18/04375-2 - Studies about the biogenesis and composition of the Leishmania spp. ribonucleoprotein complex and its regulation
• Grantee: Maria Isabel Nogueira Cano
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 19/05239-8 - Comparative study between different biophysical techniques for further understanding of the nuclear importation mechanism
• Grantee: Hamine Cristina de Oliveira
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)