Biology subjects

Fajkus, P.

Publications and source records attributed to Fajkus, P..

3 recordsLinked to original sources

bioRxiv2026

La protein binding to telomerase RNA supports an evolutionary relationship between plant and ciliate telomerase pathways

The Arabidopsis thaliana La1 (AtLa1) protein is a member of the genuine La family of RNA biogenesis proteins, which are structurally similar to the La-resembling protein 7 (LARP7) family. LARP7 proteins participate in the biogenesis of the telomerase ribonucleoprotein complex in model systems, but are absent in plants. We show that AtLa1 binds to telomerase RNA in a manner reminiscent of the Tetrahymena LARP7 protein p65. Classical in vitro methods and microscale thermophoresis (MST) were used to specify the molecular structures involved in this multi-surface interaction. AtLa1 also enhances the binding of TR to the telomerase reverse transcriptase RNA binding domain. We therefore propose that biogenesis of telomerase RNA in plants and ciliates is achieved by a similar pathway, differing in the employment of genuine La or LARP7-like proteins, respectively. We also report that the domain of unknown function (DUF3223, DeCL) found in the AtLa1 protein binding partner, Domino, is an RNA binding domain with modest TR-binding capacity. This domain is also found in plant and ciliate proteins, including plant polymerases IV/V and the Tetrahymena La protein Mlp1. Together, these suggest that RNA biogenesis pathways in plants and ciliates have a conserved evolutionary relationship, with parallels between their La proteins.

biophysics↗

bioRxiv2022

Hymenoptera (Insecta) telomerase RNAs switched to plant/ciliate-like biogenesis

In contrast to the catalytic subunit of telomerase, its RNA subunit (TR) is highly divergent in size, sequence and biogenesis pathways across eukaryotes. Current views on TR evolution assume a common origin of TRs transcribed with RNA polymerase II in Opisthokonta (the supergroup including Animalia and Fungi) and Trypanosomida on one hand, and TRs transcribed with RNA polymerase III under the control of type 3 promoter, found in TSAR and Archaeplastida supergroups (including e.g., ciliates and Viridiplantae taxa, respectively). Here we focus on unknown TRs in one of the largest Animalia order - Hymenoptera (Arthropoda) with more than 300 available representative genomes. Using a combination of bioinformatic and experimental approaches, we identify their TRs. In contrast to the presumed type of TRs (H/ACA box snoRNAs transcribed with RNA Polymerase II) corresponding to their phylogenetic position, we find here short TRs of the snRNA type, likely transcribed with RNA polymerase III under the control of the type 3 promoter. The newly described insect TRs thus question the hitherto assumed monophyletic origin of TRs across Animalia and point to an evolutionary switch in TR type and biogenesis that was associated with the divergence of Arthropods. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=134 SRC="FIGDIR/small/512496v1_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@7a691borg.highwire.dtl.DTLVardef@8a8aa2org.highwire.dtl.DTLVardef@193960forg.highwire.dtl.DTLVardef@60d364_HPS_FORMAT_FIGEXP M_FIG C_FIG

genomics↗

bioRxiv2020

Human-like telomeres in Zostera marina reveal a mode of transition from the plant to the human telomeric sequences

A previous study describing the genome of Zostera marina, the most widespread seagrass in the Northern hemisphere, revealed some genomic signatures of adaptation to the aquatic environment. Important features related to the back-to-the-sea reverse evolutionary pathway were found, such as the loss of stomatal genes, while other functions like an algal-like cell wall composition were acquired. Beyond these, the genome structure and organization were comparable to the majority of plant genomes sequenced, except for one striking feature that went unnoticed at that time: the presence of human-like instead of the expected plant-type telomeric sequences. By using different experimental approaches including FISH, NGS and Ba131 analysis, we have confirmed its telomeric location in the chromosomes of Z. marina. We have also identified its telomerase RNA subunit (TR), confirming the presence of the human-type telomeric sequence in the template region. Remarkably, this region was found to be very variable even in clades with a highly conserved telomeric sequence across their species. Based on this observation, we propose that alternative annealing preferences in the template borders can explain the transition between the plant and human telomeric sequences. The further identification of paralogues of TR in several plant genomes brought us to the hypothesis that plants may keep an increased ability to change their telomeric sequence. We discuss the implications of this occurrence in the evolution of telomeres while introducing a mechanistic model for the transition from the plant to the human telomeric sequences.

evolutionary biology↗