Rosa Rubicondior: Creationism Refuted - Horizontal Gene Transfer From A Giant Virus Into Our Complex-Celled Ancestor

Viruses as master builders of complex proteins – TU Darmstadt

Where do new genes and complex proteins come from? For intelligent design creationists, gaps in our knowledge are opportunities to invoke a supernatural designer. For scientists, they are opportunities to investigate. A discovery reported in PNAS illustrates the difference: researchers have identified a functional protein in a giant virus that offers clues to the evolutionary origins of a more elaborate family of cellular proteins.

The proteins concerned are tandem potassium channels, which allow potassium ions to cross cell membranes. In humans, members of this family help stabilise the electrical potential across membranes and regulate the excitability of nerve cells. Their distinctive architecture includes two linked pore-forming domains within each protein subunit. Although simpler precursors of other potassium-channel families are known from bacteria, the evolutionary origins of this tandem arrangement have remained uncertain.

The researchers found a gene encoding such a channel in Pyramimonas orientalis virus, which infects a single-celled marine alga. Its protein, named Kpov, contains just 178 amino acids, yet experiments in artificial membranes confirmed that it functions as an ion channel with a preference for potassium over sodium. Here, then, is a comparatively simple working version of a molecular structure associated with more elaborate cellular machinery.

The evolutionary analysis adds a particularly interesting twist. The results suggest that the virus did not simply acquire this gene recently from its host. Instead, the channel may have originated through the fusion of simpler viral pore-forming components. This supports the possibility that viruses have contributed both genetic material and molecular innovations to cellular evolution.

This is where horizontal gene transfer enters the picture. Genes need not travel exclusively from parents to offspring: they can also pass between different evolutionary lineages, with viruses participating in that exchange. The authors place their discovery in the context of evidence that eukaryotes — organisms whose cells contain nuclei — have acquired genes from DNA viruses. The present study does not establish that this particular viral channel was the ancestor of our own channels, but it identifies a plausible source of components for evolutionary innovation.

For creationism, the difficulty is not that scientists have answered every question about the origin of these proteins. It is that unanswered questions continue to produce testable hypotheses, functional experiments and new evidence, without requiring supernatural intervention. Combining existing components and transferring genetic material provide routes for evolution to explore. Invoking an invisible designer supplies neither a mechanism to investigate nor an explanation of why the molecular evidence takes the form it does.

Horizontal Gene Transfer — Evolution Beyond the Family Tree. We normally think of genes passing from parents to offspring. This is vertical inheritance, and it produces the branching pattern of descent familiar from evolutionary family trees. However, genetic material can also move between organisms outside reproduction. This is horizontal gene transfer (HGT), sometimes called lateral gene transfer. It can occur between members of the same species or across substantial evolutionary distances.

How can genes move sideways?

Bacteria can acquire DNA from their surroundings, exchange it through direct contact, or receive it through viruses that infect bacterial cells. Small DNA molecules called plasmids are particularly important vehicles for gene exchange. Viruses can also introduce genetic material into the genomes of animals, plants and other eukaryotes — organisms whose cells contain nuclei.

However, the arrival of foreign DNA is only the first step. For a transfer to have lasting evolutionary consequences, the genetic material must persist and be inherited. In animals, this generally requires its incorporation into the lineage of cells that produces eggs or sperm. A useful transferred gene may then spread through a population under natural selection.

Three examples

Antibiotic resistance in bacteria.
Resistance genes can pass between bacteria, including bacteria of different species. Plasmids can carry several such genes together, allowing a recipient to acquire resistance to multiple antibiotics. The transfer supplies an existing genetic capability; subsequent exposure to antibiotics can favour bacteria carrying it. Further information: US Centers for Disease Control and Prevention.

A plant gene in a plant-eating insect.
The whitefly Bemisia tabaci acquired a plant-derived gene, BtPMaT1, whose product helps neutralise defensive plant chemicals. Researchers tested its function by silencing the gene, which impaired the insects’ ability to deal with those toxins. This is an example of genetic material crossing the boundary between plants and animals and contributing to an ecological adaptation. Research paper: Xia and colleagues, 2021.

Viral genes recruited into mammalian reproduction.
Syncytins originated from retroviral envelope genes — genes associated with the membrane-fusing machinery of viruses. Following ancient incorporation into ancestral genomes, some were recruited for cell fusion during placental development. Different mammalian lineages independently acquired such genes. Their history illustrates both the acquisition of foreign DNA and co-option: an existing biological capability taking on a new role. Research on the evolutionary history of syncytins.

Does gene transfer create new genes?

A transferred gene can be new to its recipient without being newly evolved. Horizontal transfer explains how genetic material moves; its original evolution is a separate question. Once acquired, however, genes can undergo mutation, duplication, fusion and changes in regulation, potentially producing further innovations. Transfer and subsequent modification are complementary evolutionary processes.

Where does the giant-virus discovery fit?

Pyramimonas orientalis virus is a large DNA virus that infects a single-celled marine alga. Researchers found that it encodes a small but functional tandem potassium channel. Their analysis suggests that this channel may have arisen through the fusion of simpler viral components, supporting the possibility that viruses supplied components for the evolution of cellular channels. The study does not demonstrate a specific transfer from this virus into an ancestor of humans or other organisms. Research paper: Rauh and colleagues, 2026.

The evolutionary lesson: genomes are historical products of inheritance, modification and, sometimes, acquisition from other lineages. Horizontal gene transfer adds connections between branches of the evolutionary tree; it does not overturn common descent or require a supernatural source of genetic information.

The publication of the paper in PNAS was announced by a news item from Technische Universität Darmstadt:

Viruses as master builders of complex proteins

PNAS study on the origin of tandem potassium channels

Researchers from TU Darmstadt and Bonn-Rhein-Sieg University of Applied Sciences, working with international partners, have discovered a gene for a tandem potassium channel in an algal virus. The finding supports the view that giant viruses may have contributed significantly to the evolution of complex proteins. The results have been published in the journal Proceedings of the National Academy of Sciences (PNAS).

Dr Oliver Rauh (Bonn-Rhein-Sieg University of Applied Sciences) carrying out electrophysiological measurements. The scientist is collaborating with researchers from Technical University of Darmstadt as part of the ‘CytoTransport’ research cluster.

Picture: Eric Lichtenscheidt/H-BRS

So-called tandem potassium channels perform important functions in human physiology. Because they can conduct potassium ions (K⁺) across the cell membrane, they help, among other things, to stabilise the membrane potential and thereby regulate the electrical excitability of nerve cells. Structurally, they differ from all other potassium channels in that two of their four pore-forming subunits are directly linked to each other. It is this tandem-like linkage of the subunits that gives them their name.

No precursor in bacteria

A subunit of the newly discovered tandem potassium channel, in which two pore-forming protein domains are directly linked to one another. Two of these subunits form the functional ion channel.
Picture: Oliver Rauh

Unlike every other type of potassium channel, precursors of tandem potassium channels have no be found in bacteria, which has in the past raised questions about their evolutionary origin. In a new article in PNAS, an international team including researchers from the Department of Biology at TU Darmstadt and the Department of Natural Sciences at Bonn-Rhein-Sieg University of Applied Sciences (H-BRS) now reports on a DNA virus that infects marine algae and whose genome contains a gene for a tandem potassium channel. ‘Our experiments show that this gene encodes a protein with the functional properties of a potassium channel,’ says Dr Oliver Rauh, a scientist in the DFG research network ‘CytoTransport’ at H-BRS.

The authors of the study also examined the evolutionary relationships between the newly discovered viral channel and known tandem potassium channels, and made a striking discovery: contrary to what is assumed for most viral genes, the newly discovered potassium channel gene did not end up in the viral genome by being stolen from the host’s genetic material. Rather, the gene appears to be of viral origin. ‘This finding further reinforces a new perspective according to which the giant mimiviruses, to which this virus belongs, have played a central role in the evolution of proteins in higher organisms,’ emphasises Professor Gerhard Thiel of the Department of Biology at TU Darmstadt. The results of the study also underline that these viruses are rich sources of highly interesting proteins. Other researchers have already discovered a light-controlled ion channel in the same virus, which is used in optogenetics, a field recently recognised with the Nobel Prize.

Publication:
O. Rauh,S. Mach,O. Clarke,J. Toews,J.L. Van Etten,M. Althaus,A. Moroni, & G. Thiel
A functional two-pore-domain K⁺ channel from a large DNA virus. Proc. Natl. Acad. Sci. U.S.A. 123(43) e2626158123, https://doi.org/10.1073/pnas.2626158123 (2026).

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Significance
While the evolutionary history of the pore and its sensor domains in modern K⁺ channels can be traced back to prokaryotes, the origin of a tandem architecture remains unknown; such structures do not occur in bacteria. Here, we highlight a possible contribution by giant dsDNA viruses to K⁺ channel evolution. A member of the giant Mimiviruses, which infects a single-celled marine alga, contains a gene for a tandem K⁺ channel with structural hallmarks of K⁺ channel pores. This channel is functional and exhibits a 10-fold selectivity for K⁺ over Na⁺. As eukaryotic cells have acquired genes from DNA viruses during evolution, these viruses may have acted as mediators of horizontal gene transfer or as primary source of K⁺ channel genes.

Abstract
The evolutionary history of proteins helps to understand their structure/function correlates and suggests on how functional complexity evolved from primitive precursors. In the superfamily of K⁺ channels, functional features of complex eukaryotic inward rectifier (Kir) channels and voltage-dependent (Kv) channels could be understood in terms of an increase in structural complexity of their prokaryotic precursors. K2P channels, which are made from tandem repeats of two pore domains, are not found in prokaryotes and their evolutionary origin is still unknown. In searching for primitive K2P channel precursors, we screened the genomes of nucleocytoplasmic large DNA viruses (NCLDVs) for genes coding for K2P channels. This was motivated by two reasons: NCLDVs are already known for coding primitive Kir type channels, and they play important roles in the evolution of eukaryotes. Here, we report that the NCLDV Pyramimonas orientalis virus codes for K2P-like K⁺ channels. With only 178 amino acids and no cytosolic domains, this Kpov protein is much smaller than any eukaryotic K2P channel, but still functional as K⁺ selective channel in lipid bilayers. Phylogenetic analysis suggests that Kpov is not the product of molecular piracy from the host but may result from fusion of primitive viral K⁺ channel pore domains.

Fig. 1.

Modular evolution of K⁺ channels and architecture of viral K2P-like channel Kpov. (A) K⁺ channels presumably evolved from basic pore-forming monomers with a conserved P-loop domain which contains the selectivity filter and connects two transmembrane domains TMD1 and TMD2. During evolution the pore module acquired additional building blocks with sensor function as cytosolic domains (green) and/or as additional TMDs (yellow). This led to distinct K⁺ channel families with diverse structural and functional features such as inward rectifiers (Kir) and voltage gated channels (Kv). A specific case is Two-Pore channels (K2P) where the functional K2P channel is a dimer of two subunits (gray and pink), each subunit containing two pore domains and four pore domains forming the functional pore. Top row: Kir and Kv subunits assemble in a functional channel as a tetramer where the pore module forms the central unit. In K2P channels the functional protein is made of dimers of monomers with two pore domains. A structural peculiarity of animal K2P channels is an extended loop in the first pore domain (red), which forms the typical helical cap at the entrance to these channels. K⁺ channels with a Kir and Kv type architecture were discovered in prokaryotes underpinning that they already occurred early in evolution. K2P type channels have not been discovered in prokaryotes. The dotted line indicates one possible hypothesis according to which these channels may have first occurred in early extinct eukaryotes. (B) Primary sequence of Kpov. Position of transmembrane helices (TMD) 1 to 4, pore helices (P-loop), and selectivity filter domains (SF) are underlined; critical amino acids of the K⁺ channel signature sequence of the two SFs are indicated in color: the GYG motif in blue, and the position of a canonical threonine upstream (red) and anionic amino acid downstream of GYG (green). (C) Simplified phylogeny of Nucleocytoviricota according to (9) including prototype viral K⁺ channels and viruses in which the respective genes were detected. The Kpov channel originates from PoV, in the family of Allomimiviridae. (D) Side view and (E) top view of Kpov channel structure as predicted by AlphaFold2 based on the amino acid sequence shown in B. The two pore domains (PD1 and PD2) are colored in gray and pink, respectively, and the position of the individual pore domains in the tandem organization are indicated. (F and G) Side-view orientation with two opposing monomers of PD1 (F) and PD2 (G) with indication of structural details and corresponding selectivity filter sequences in which the consensus motif is color-coded as in B. The dashed circles in B, F, and G mark the position of the ion pathway with location of K⁺ binding sites S1–S₄.

O. Rauh,S. Mach,O. Clarke,J. Toews,J.L. Van Etten,M. Althaus,A. Moroni, & G. Thiel
A functional two-pore-domain K⁺ channel from a large DNA virus. Proc. Natl. Acad. Sci. U.S.A. 123(43) e2626158123, https://doi.org/10.1073/pnas.2626158123 (2026).

Copyright: © 2026 The authors.
Published by National Academy of Science of the USA. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

What makes this discovery significant is not that it settles every question about the evolution of potassium channels, but that it supplies another piece of evidence with which to investigate their origins. A small, functional viral channel, together with evidence consistent with the fusion of simpler components, offers a plausible route towards greater molecular complexity. The possible contribution of viruses to cellular channels remains a hypothesis to investigate, rather than a conclusion to assume.

This is precisely how evolutionary biology advances. Researchers compare sequences, examine structures, test functions and use the results to distinguish between competing explanations. Horizontal gene transfer adds another dimension to that history: useful genetic material need not originate within the lineage that eventually employs it. Evolution can modify inherited components, combine them and recruit material acquired from elsewhere, without foresight or a predetermined goal.

For intelligent design creationism, an unexplained origin is too often treated as evidence that natural processes could not have produced the structure concerned. But a gap in knowledge establishes no such impossibility. Nor does inserting a supernatural designer into that gap explain the molecular relationships, identify a mechanism or provide an independently testable account of what happened.

The contrast is therefore between a scientific explanation that becomes more detailed as evidence accumulates and a claim of design that adds nothing to the investigation. Here, another apparent mystery has yielded a working protein and clues to its evolutionary history. The remaining questions are invitations to further research, not evidence of supernatural intervention.

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