Affiliation:
1. University of Cambridge
2. University of Perpignan
3. University of Glasgow
4. Wellcome Sanger Institute
Abstract
Abstract
Background
The genomic region that lies between the telomere and chromosome body, termed the subtelomere, is heterochromatic, repeat-rich, and frequently undergoes rearrangement. Within this region, large-scale structural changes enable gene diversification, and, as such, large multicopy gene families are often found at the subtelomere. In some parasites, genes associated with proliferation, invasion, and survival are often found in these regions, where they benefit from the subtelomere's highly plastic, rapidly changing nature. The increasing availability of complete (or near complete) parasite genomes provides an opportunity to investigate these typically poorly defined and overlooked genomic regions and potentially reveal relevant gene families necessary for the parasite’s lifestyle.
Results
Using the latest chromosome-scale genome assembly and hallmark repeat richness observed at chromosome termini, we have identified and characterised the subtelomeres of Schistosoma mansoni, a metazoan parasitic flatworm that infects over 250 million people worldwide. Approximately 10.5% of the S. mansoni genome is classified as subtelomeric, and, in line with other organisms, we find these regions to be gene-poor but rich in transposable elements. We find that S. mansoni subtelomeres have undergone extensive interchromosomal exchange and that these sites disproportionately contribute to the 2.3% of the genome derived from segmental duplications. This recombination has led to the expansion of subtelomeric gene clusters containing 103 genes, including the immunomodulatory annexins and other gene families with unknown roles. The largest of these is a 49-copy “plexin domain-containing protein” cluster, exclusively expressed in the tegument - the tissue located at the host-parasite physical interface - of intramolluscan life stages.
Conclusions
We propose that subtelomeric regions act as a genomic playground for trial-and-error of gene duplication and subsequent divergence. Owing to the importance of subtelomeric genes in other parasites, gene families implicated in this subtelomeric expansion within S. mansoni warrant further characterisation for a potential role in parasitism.
Publisher
Research Square Platform LLC
Reference105 articles.
1. Comprehensive analysis of human subtelomeres by whole genome mapping;Young E;PLoS Genet,2020
2. Subtelomeric Transcription and its Regulation;Kwapisz M;J Mol Biol,2020
3. Structural variation in the 3D genome;Spielmann M;Nat Rev Genet,2018
4. The telomere paradox: stable genome preservation with rapidly evolving proteins;Saint-Leandre B;Trends Genet,2020
5. Adam E, Islam T, Ranjan D, Riethman H. Nanopore Guided Assembly of Segmental Duplications near Telomeres. In: 2019 IEEE 19th International Conference on Bioinformatics and Bioengineering (BIBE). IEEE; 2019. p. 60–5.