idw – Informationsdienst Wissenschaft

Nachrichten, Termine, Experten

Grafik: idw-Logo
Grafik: idw-Logo

idw - Informationsdienst
Wissenschaft

Science Video Project
idw-Abo

idw-News App:

AppStore

Google Play Store



Instance:
Share on: 
06/29/2023 20:00

Virus-like transposons wage war on the species barrier

Daniel F. Azar, PhD IMBA Communications
IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH

    Scientists have known for decades that genes can be transferred from one species to another, both in animals and plants. However, the mechanism of how such an unlikely event occurs remained unknown. Now, researchers from Alejandro Burga’s lab at the Institute of Molecular Biotechnology (IMBA) of the Austrian Academy of Sciences identify a vector of horizontal gene transfer (HGT) in worms. The findings, published on June 29 in Science, could lead to the discovery of further vectors of HGT in eukaryotes and might find applications in pathogen control.

    Fish living in the Arctic and Antarctic oceans have evolved ingenious strategies to prevent their blood and tissues from freezing in the inhospitable polar waters. One such adaptive strategy is the evolution of genes that produce antifreeze proteins. However, over a decade ago, scientists were astounded to discover that herrings and smelts—two completely different species—have the exact same antifreeze protein encoded in their genomes, indicating a gene transfer between them. Examples such as this raise the question: how can genes “jump” between completely different species? This rare phenomenon, known as horizontal gene transfer (HGT), has puzzled evolutionary biologists for a long time. And despite new instances of HGT being discovered across all branches of life over the years, the mechanisms responsible for these transfers have largely remained unknown.

    Now, scientists from Alejandro Burga’s group at IMBA not only catch an HGT event in the animal kingdom red-handed, but they also identify one of its long-sought vectors. By means of genetic detective work, Burga and his team showed an event of HGT between two reproductively isolated worm species that are genetically as different from each other as humans are from fish. More importantly, they could identify what caused it: a family of virus-like transposons called Mavericks.

    Nailing down a culprit: Mavericks as vectors of HGT

    “Mavericks were already known as a class of transposons, but our work links them to HGT for the first time,” says IMBA group leader Alejandro Burga, the study’s corresponding author. “We knew that HGT did take place between animal species, but we had no idea how. This is the first time that we could definitively nail down a culprit,” adds co-first author Sonya Widen, a postdoctoral fellow in the Burga lab.

    When Mavericks were discovered in the mid-2000s, they were initially thought to be large transposons, selfish genetic elements that jump and self-propagate in the genome at the expense of their host. Mavericks were quickly reported in most branches of eukaryotes, including humans, thus establishing that they originated a long time ago.

    Transposons and viruses, nature’s melting pot?

    Soon, evidence that Mavericks contained genes encoding viral elements, such as a capsid and a DNA polymerase, started to surface. “The evolution of transposons and viruses is tightly intertwined,” says Burga. However, the capsid and the DNA polymerase are not enough to allow a transposon to jump from its host’s genome and infect the cells of a completely different host. Now, the IMBA researchers found the missing link: Mavericks in worm genomes have acquired a so-called fusogen protein, a transmembrane protein that mediates membrane fusion between different cells. By acquiring a fusogen, the authors hypothesize that worm Mavericks became capable of forming virus-like particles that can fuse with another organism’s cell membranes and infect them. “To our knowledge, no fusogen has been reported in Mavericks before. Thus, we think that worm Mavericks might have picked up their sequence from a virus,” says Widen. “Transposons and viruses can be thought of as nature’s melting pot. Their union can have unpredictable repercussions and lead to genomic innovation,” says Burga.

    Demonstrating the significance of HGT in worms

    In the present study, the IMBA team led by Alejandro Burga and co-first authors Sonya Widen and Israel Campo Bes, a former master’s student in the Burga lab, came across HGT “totally by chance”, as Widen says. In fact, the team was studying the evolutionary origin of a selfish element in the nematode Caenorhabditis briggsae. Doing some detective work, they were able to trace the sequence of this selfish gene back to another nematode, C. plicata, which carried an almost identical copy. This finding is surprising because C. briggsae and C. plicata are two reproductively isolated species. “Their genomes are as divergent as those of humans and fish, and yet they both have an almost identical gene that clearly shows features of an evolutionarily recent HGT event,” says Campo Bes. “By carefully looking at the genome of C. plicata, we found that the ancestral sequence that gave rise to the selfish gene in C. briggsae was embedded inside a Maverick in C. plicata. The fact that this newly introduced gene subsequently evolved into a novel selfish gene in C. briggsae demonstrates the impact of HGT on genome evolution,” Widen explains. The IMBA team then went on to show that Mavericks are responsible for dozens of independent HGT transfer events between worm species belonging to different genera and found all around the globe.

    Agricultural and medical relevance

    The IMBA scientists argue that the union between transposons and viruses is a key factor in mediating HGT. While still finding it hard to believe their success, they recognize the impact that their findings could have on lifting the mysteries of HGT. “I was convinced that we were looking at a case of HGT when we first saw these results in the lab, but I was also sure that we would never find out how it happened. Yet, the stars aligned,” says Burga, who also predicts that Mavericks and similar virus-like transposable elements could mediate HGT in vertebrates and other eukaryotes. Finally, the team foresees possible applications both in the lab and as pest control measures against parasitic worm species: “If Maverick-mediated HGT is shown to be broadly applicable to any nematode species, it has the potential to become an invaluable resource. Beyond strict lab and research applications such as the genetic manipulation of non-model nematodes, such a resource could allow us, in the future, to genetically modify parasitic nematode species that might be of agricultural or medical relevance,” concludes Burga.

    Sonya A. Widen is a postdoctoral fellow in the Burga lab at IMBA and a member of the Vienna International Postdoctoral (VIP2) Fellowship Program at the Vienna BioCenter. Israel Campo Bes, a former master’s student in the Burga lab, is currently pursuing a PhD at the Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Barcelona, Spain.

    Original publication:
    Sonya A. Widen*, Israel Campo Bes*, Alevtina Koreshova, Pinelopi Pliota, Daniel Krogull, and Alejandro Burga, Virus-like transposons cross the species barrier and drive the evolution of genetic incompatibilities. Science (2023). DOI: 10.1126/science.ade0705
    https://doi.org/10.1126/science.ade0705
    *Co-first authors

    About IMBA:
    The Institute of Molecular Biotechnology (IMBA) of the Austrian Academy of Sciences (ÖAW) is one of Europe’s leading biomedical research institutes. IMBA is located at the Vienna BioCenter, Austria's vibrant cluster of universities, research institutes, and biotech companies. IMBA research topics include chromosome biology, RNA biology, selfish elements and silencing mechanisms, functional genomics, cell and developmental biology, stem cell biology, molecular medicine, neuroscience, organoid research, and disease models.


    Original publication:

    Sonya A. Widen*, Israel Campo Bes*, Alevtina Koreshova, Pinelopi Pliota, Daniel Krogull, and Alejandro Burga, Virus-like transposons cross the species barrier and drive the evolution of genetic incompatibilities. Science (2023). DOI: 10.1126/science.ade0705
    https://doi.org/10.1126/science.ade0705
    *Co-first authors


    More information:

    https://bit.ly/MavericksHGT


    Images

    A Maverick virus-like particle as a vector of horizontal gene transfer (HGT). ©IMBA-IMP Graphics
    A Maverick virus-like particle as a vector of horizontal gene transfer (HGT). ©IMBA-IMP Graphics
    IMBA-IMP Graphics
    ©IMBA-IMP Graphics

    Sonya Widen, co-first author of the study and postdoctoral fellow in the Burga research group at IMBA. ©IMBA/Cooper
    Sonya Widen, co-first author of the study and postdoctoral fellow in the Burga research group at IMB ...
    IMBA/Cooper
    ©IMBA/Cooper


    Attachment
    attachment icon Israel Campo Bes, co-first author of the study and former master’s student in the Burga research group at IMBA. ©Private

    Criteria of this press release:
    Journalists, Scientists and scholars, Students, all interested persons
    Biology, Chemistry, Environment / ecology, Medicine
    transregional, national
    Scientific Publications
    English


     

    Help

    Search / advanced search of the idw archives
    Combination of search terms

    You can combine search terms with and, or and/or not, e.g. Philo not logy.

    Brackets

    You can use brackets to separate combinations from each other, e.g. (Philo not logy) or (Psycho and logy).

    Phrases

    Coherent groups of words will be located as complete phrases if you put them into quotation marks, e.g. “Federal Republic of Germany”.

    Selection criteria

    You can also use the advanced search without entering search terms. It will then follow the criteria you have selected (e.g. country or subject area).

    If you have not selected any criteria in a given category, the entire category will be searched (e.g. all subject areas or all countries).