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Santos da Silva, M.

Publications and source records attributed to Santos da Silva, M..

2 recordsLinked to original sources

Functional characterization of N-acetyltransferase 10 (NAT10) in Leishmania mexicana

Leishmania presents a complex life cycle that involves both invertebrate and vertebrate hosts. By regulating gene expression, protein synthesis, and metabolism, the parasite can adapt to various environmental conditions. This regulation occurs mainly at the post-transcriptional level and may involve epitranscriptomic modifications of RNAs. Recent studies have shown that mRNAs in humans undergo a modification known as N4-acetylcytidine (ac4C) catalyzed by the enzyme N-acetyltransferase (NAT10), impacting mRNAs stability and translation. Here, we characterized the NAT10 homologue of L. mexicana, finding that the enzyme exhibits all the conserved acetyltransferase domains and although failed to functionally complement the Kre33 mutant in Saccharomyces cerevisiae, has in vitro acetyltransferase activity. We also discovered that LmexNAT10 is nuclear, and seems essential, as evidenced by unsuccessful attempts to obtain null mutant parasites. Phenotypic characterization of single-knockout parasites revealed that LmexNAT10 affects the multiplication of procyclic forms and the promastigote-amastigote differentiation. Additionally, in vivo infection studies using the invertebrate vector Lutzomyia longipalpis showed a delay in the parasite differentiation into metacyclics. Finally, we observed changes in the cell cycle progression and protein synthesis in the mutant parasites. Together, these results suggest that LmexNAT10 might be important for parasite differentiation, potentially by regulating ac4C levels.

microbiology↗

Comprehensive Analysis of Nascent Transcriptome Reveals Diverse Transcriptional Profiles Across the Trypanosoma cruzi Genome Underlining the Regulatory Role of Genome Organization, Chromatin Status, and Cis-Acting Elements

Trypanosomatids are eukaryotic parasites exhibiting polycistronic transcription and trans-splicing. Post-transcriptional mechanisms are acknowledged as pivotal in gene expression regulation of their protein-coding genes. To comprehensively investigate the impact of transcription on gene expression in Trypanosoma cruzi and the association with the epigenetic landscape, we conducted a genome-wide nascent transcriptomic analysis. Our findings reveal significant asymmetrical transcriptional abundance across the genome, notably between polycistronic transcription units (PTUs) enriched in conserved genes (core PTUs) and those containing virulence genes (disruptive PTUs). We found that trypanosomes exploit linear genome organization to regulate transcription abundance by embedding virulence genes into highly transcribed core-enriched PTUs, by positioning PTUs near non-coding regions of small non-coding RNAs (e.g., tRNAs, snoRNAs), and by placing core CDSs in PTUs of various sizes. Additionally, we found correlations between open chromatin status and nascent transcript levels, both globally and particularly at transcription starting regions (divergent strand switch regions - dSSRs), indicating a crucial role for chromatin architecture in transcriptional regulation. While both core and disruptive dSSRs exhibit similar levels of some epigenetic marks (H2B.V deposition and 5mC), disruptive dSSRs display significantly higher 5hmC content and nucleosome occupancy compared to core dSSRs. Furthermore, we identified distinct conserved motifs within dSSRs of core and disruptive PTUs. These findings challenge the notion of constitutive and uniform transcription in T. cruzi, underscoring the paramount importance of linear genome organization, cis-acting motifs, and chromatin landscape in transcriptional regulation.

molecular biology↗