An Evolutionary View of Trypanosoma Cruzi Telomeres.

Jose Luis Ramirez

doi:10.3389/fcimb.2019.00439

Abstract

Like in most eukaryotes, the linear chromosomes of Trypanosoma cruzi end in a nucleoprotein structure called the telomere, which is preceded by regions of variable length called subtelomeres. Together telomeres and subtelomeres are dynamic sites where DNA sequence rearrangements can occur without compromising essential interstitial genes or chromosomal synteny. Good examples of subtelomeres involvement are the expansion of human olfactory receptors genes, variant surface antigens in Trypanosoma brucei, and Saccharomyces cerevisiae mating types. T. cruzi telomeres are made of long stretches of the hexameric repeat 5′-TTAGGG-OH-3′, and its subtelomeres are enriched in genes and pseudogenes from the large gene families RHS, TS and DGF1, DEAD/H-RNA helicase and N-acetyltransferase, intermingled with sequences of retrotransposons elements. In particular, members of the Trans-sialidase type II family appear to have played a role in shaping the current T. cruzi telomere structure. Although the structure and function of T. cruzi telomeric and subtelomeric regions have been documented, recent experiments are providing new insights into T. cruzi's telomere-subtelomere dynamics. In this review, I discuss the co-evolution of telomere, subtelomeres and the TS gene family, and the role that these regions may have played in shaping T. cruzi's genome.

Highlights

Trypanosome cruzi causes Chagas disease a debilitating and often lethal malaise affecting millions of people in Latin American countries
Vestiges of these events are the salad of sequences derived from retrotransposon elements and Retrotransposons Hot Spot (RHS) genes scattered through the genome, and in T. cruzi subtelomeres (Figure 1)
Based on these observations and in the composition of T. cruzi telomeres and subtelomeres, we proposed that subtelomeres were places where the variability of some of these multigene families was generated, and in later events, the gene variants were mobilized to different locations in the genome (Kim et al, 2005)

Summary

Jose Luis Ramirez*

Fundación Instituto de Estudios Avanzados and United Nations University UNU-BIOLAC, Caracas, Venezuela. The linear chromosomes of Trypanosoma cruzi end in a nucleoprotein structure called the telomere, which is preceded by regions of variable length called subtelomeres. Together telomeres and subtelomeres are dynamic sites where DNA sequence rearrangements can occur without compromising essential interstitial genes or chromosomal synteny. Members of the Trans-sialidase type II family appear to have played a role in shaping the current T. cruzi telomere structure. The structure and function of T. cruzi telomeric and subtelomeric regions have been documented, recent experiments are providing new insights into T. cruzi’s telomere-subtelomere dynamics. I discuss the co-evolution of telomere, subtelomeres and the TS gene family, and the role that these regions may have played in shaping T. cruzi’s genome

INTRODUCTION

GENE FAMILY IN SHAPING ITS GENOME

GENE FAMILIES AND SUBTELOMERES

HYPOTHETICAL MECHANISMS TO GENERATE GENE VARIABILITY

Findings

CONCLUSIONS