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Ignatochkina A, Iguchi J, Kore A, Ho C. Trypanosome mRNA recapping is triggered by hypermethylation originating from cap 4. Nucleic Acids Res 2024; 52:10645-10653. [PMID: 39011881 PMCID: PMC11417388 DOI: 10.1093/nar/gkae614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 06/01/2024] [Accepted: 07/12/2024] [Indexed: 07/17/2024] Open
Abstract
RNA methylation adjacent to the 5' cap plays a critical role in controlling mRNA stability and protein synthesis. In trypanosomes the 5'-terminus of mRNA is protected by hypermethylated cap 4. Trypanosomes encode a cytoplasmic recapping enzyme TbCe1 which possesses an RNA kinase and guanylyltransferase activities that can convert decapped 5'-monophosphate-terminated pRNA into GpppRNA. Here, we demonstrated that the RNA kinase activity is stimulated by two orders of magnitude on a hypermethylated pRNA derived from cap 4. The N6, N6-2'-O trimethyladenosine modification on the first nucleotide was primarily accountable for enhancing both the RNA kinase and the guanylyltransferase activity of TbCe1. In contrast, N6 methyladenosine severely inhibits the guanylyltransferase activity of the mammalian capping enzyme. Furthermore, we showed that TbCmt1 cap (guanine N7) methyltransferase was localized in the cytoplasm, and its activity was also stimulated by hypermethylation at 2'-O ribose, suggesting that TbCe1 and TbCmt1 act together as a recapping enzyme to regenerate translatable mRNA from decapped mRNA. Our result establishes the functional role of cap 4 hypermethylation in recruitment and activation of mRNA recapping pathway. Methylation status at the 5'-end of transcripts could serve as a chemical landmark to selectively regulate the level of functional mRNA by recapping enzymes.
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Affiliation(s)
- Anna V Ignatochkina
- Department of Infection Biology, Graduate School of Comprehensive Human Sciences, Institute of Medicine, University of Tsukuba, Ibaraki 305-8575, Japan
| | - Jesavel A Iguchi
- Department of Infection Biology, Graduate School of Comprehensive Human Sciences, Institute of Medicine, University of Tsukuba, Ibaraki 305-8575, Japan
| | - Anilkumar R Kore
- Life Sciences Solutions Group, Thermo Fisher Scientific, 2130 Woodward Street, Austin, TX 78744-1832, USA
| | - C Kiong Ho
- Department of Infection Biology, Graduate School of Comprehensive Human Sciences, Institute of Medicine, University of Tsukuba, Ibaraki 305-8575, Japan
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Bhattacharya A, Sharma M, Pakkinathan C, Rosen BP, Leprohon P, Ouellette M. Genomewide Analysis of Mode of Action of the S-Adenosylmethionine Analogue Sinefungin in Leishmania infantum. mSystems 2019; 4:e00416-19. [PMID: 31615876 PMCID: PMC6794121 DOI: 10.1128/msystems.00416-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 09/30/2019] [Indexed: 11/20/2022] Open
Abstract
To further our understanding of one-carbon metabolism in the protozoan parasite Leishmania, we conducted genomic screens to study how the parasite responded to sinefungin (SNF) selection. SNF is a structural analogue of S-adenosylmethionine (AdoMet), a key methyl group donor to a number of biomolecules. One screen consisted of sequencing SNF-resistant mutants generated by stepwise selection with gradually increasing drug concentrations. These studies demonstrated deletion of the AdoMet transporter (AdoMetT1) by intergenic recombination as a crucial loss-of-function marker for SNF resistance. The second screen consisted of Cos-seq, a gain-of-function cosmid-based genomewide functional screen with increasing SNF concentration coupled to next-generation sequencing. Cosmids enriched in that screen and sequenced led to the identification of (i) the AdoMet synthetase (METK) as the major SNF target, (ii) an mRNA [(guanine-N7)-methyltransferase (CMT1)], (iii) a leucine carboxyl methyltransferase (LCMT), (iv) two tryparedoxin genes, and (v) two protein phosphatase regulatory genes. Further functional exploration indicated that LCMT interacts with one phosphatase catalytic subunit (PP2AC) and that mutation of the C-terminal leucine residue of PP2AC affects sinefungin susceptibility. These holistic screens led to the identification of transporters, biosynthetic genes, RNA and protein methyltransferases, as well as phosphatases linked to AdoMet-mediated functions in Leishmania IMPORTANCE The two main cellular metabolic one-carbon donors are reduced folates and S-adenosylmethionine, whose biosynthetic pathways have proven highly effective in chemotherapeutic interventions in various cell types. Sinefungin, a nucleoside analogue of S-adenosylmethionine, was shown to have potent activity against the protozoan parasite Leishmania Here, we studied resistance to sinefungin using whole-genome approaches as a way to further our understanding of the role of S-adenosylmethionine in this parasite and to reveal novel potential drug targets. These approaches allowed the characterization of novel features related to S-adenosylmethionine function in Leishmania which could further help in the development of sinefungin-like compounds against this pathogenic parasite.
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Affiliation(s)
- Arijit Bhattacharya
- Division of Infectious Disease and Immunity, CHU de Quebec Research Center, Quebec, Quebec, Canada
- Department of Microbiology, Infectious Disease and Immunology, University Laval, Quebec, Quebec, Canada
| | - Mansi Sharma
- Division of Infectious Disease and Immunity, CHU de Quebec Research Center, Quebec, Quebec, Canada
- Department of Microbiology, Infectious Disease and Immunology, University Laval, Quebec, Quebec, Canada
| | - Charles Pakkinathan
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, USA
| | - Barry P Rosen
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, USA
| | - Philippe Leprohon
- Division of Infectious Disease and Immunity, CHU de Quebec Research Center, Quebec, Quebec, Canada
- Department of Microbiology, Infectious Disease and Immunology, University Laval, Quebec, Quebec, Canada
| | - Marc Ouellette
- Division of Infectious Disease and Immunity, CHU de Quebec Research Center, Quebec, Quebec, Canada
- Department of Microbiology, Infectious Disease and Immunology, University Laval, Quebec, Quebec, Canada
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Galloway A, Cowling VH. mRNA cap regulation in mammalian cell function and fate. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2019; 1862:270-279. [PMID: 30312682 PMCID: PMC6414751 DOI: 10.1016/j.bbagrm.2018.09.011] [Citation(s) in RCA: 123] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 09/13/2018] [Accepted: 09/30/2018] [Indexed: 12/17/2022]
Abstract
In this review we explore the regulation of mRNA cap formation and its impact on mammalian cells. The mRNA cap is a highly methylated modification of the 5' end of RNA pol II-transcribed RNA. It protects RNA from degradation, recruits complexes involved in RNA processing, export and translation initiation, and marks cellular mRNA as "self" to avoid recognition by the innate immune system. The mRNA cap can be viewed as a unique mark which selects RNA pol II transcripts for specific processing and translation. Over recent years, examples of regulation of mRNA cap formation have emerged, induced by oncogenes, developmental pathways and during the cell cycle. These signalling pathways regulate the rate and extent of mRNA cap formation, resulting in changes in gene expression, cell physiology and cell function.
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Affiliation(s)
- Alison Galloway
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Victoria H Cowling
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK.
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