Navigation Links
Study of giant viruses shakes up tree of life
Date:9/13/2012

CHAMPAIGN, Ill. A new study of giant viruses supports the idea that viruses are ancient living organisms and not inanimate molecular remnants run amok, as some scientists have argued. The study reshapes the universal family tree, adding a fourth major branch to the three that most scientists agree represent the fundamental domains of life.

The new findings appear in the journal BMC Evolutionary Biology.

The researchers used a relatively new method to peer into the distant past. Rather than comparing genetic sequences, which are unstable and change rapidly over time, they looked for evidence of past events in the three-dimensional, structural domains of proteins. These structural motifs, called folds, are relatively stable molecular fossils that like the fossils of human or animal bones offer clues to ancient evolutionary events, said University of Illinois crop sciences and Institute for Genomic Biology professor Gustavo Caetano-Anolls, who led the analysis.

"Just like paleontologists, we look at the parts of the system and how they change over time," Caetano-Anolls said. Some protein folds appear only in one group or in a subset of organisms, he said, while others are common to all organisms studied so far.

"We make a very basic assumption that structures that appear more often and in more groups are the most ancient structures," he said.

Most efforts to document the relatedness of all living things have left viruses out of the equation, Caetano-Anolls said.

"We've always been looking at the Last Universal Common Ancestor by comparing cells," he said. "We never added viruses. So we put viruses in the mix to see where these viruses came from."

The researchers conducted a census of all the protein folds occurring in more than 1,000 organisms representing bacteria, viruses, the microbes known as archaea, and all other living things. The researchers included giant viruses because these viruses are large and complex, with genomes that rival and in some cases exceed the genetic endowments of the simplest bacteria, Caetano-Anolls said.

"The giant viruses have incredible machinery that seems to be very similar to the machinery that you have in a cell," he said. "They have complexity and we have to explain why."

Part of that complexity includes enzymes involved in translating the genetic code into proteins, he said. Scientists were startled to find these enzymes in viruses, since viruses lack all other known protein-building machinery and must commandeer host proteins to do the work for them.

In the new study, the researchers mapped evolutionary relationships between the protein endowments of hundreds of organisms and used the information to build a new universal tree of life that included viruses. The resulting tree had four clearly differentiated branches, each representing a distinct "supergroup." The giant viruses formed the fourth branch of the tree, distinct from bacteria, archaea and eukarya (plants, animals and all other organisms with nucleated cells).

The researchers discovered that many of the most ancient protein folds those found in most cellular organisms were also present in the giant viruses. This suggests that these viruses appeared quite early in evolution, near the root of the tree of life, Caetano-Anolls said.

The new analysis adds to the evidence that giant viruses were originally much more complex than they are today and experienced a dramatic reduction in their genomes over time, Caetano-Anolls said. This reduction likely explains their eventual adoption of a parasitic lifestyle, he said. He and his colleagues suggest that giant viruses are more like their original ancestors than smaller viruses with pared down genomes.

The researchers also found more evidence that viruses are key "spreaders of information," Caetano-Anolls said.

"The protein structures that other organisms share with viruses have a particular quality, they are (more widely) distributed than other structures," he said. "Each and every one of these structures is an incredible discovery in evolution. And viruses are distributing this novelty," he said.

Most studies of giant viruses are "pointing in the same direction," Caetano-Anolls said. "And this study offers more evidence that viruses are embedded in the fabric of life."


'/>"/>
Contact: Diana Yates
diya@illinois.edu
217-333-5802
University of Illinois at Urbana-Champaign
Source:Eurekalert  

Related biology news :

1. Study implicates marijuana use in pregnancy problems
2. University of Tennessee, ORNL lead national team to study nuclear fusion reactors
3. Study provides first-time analysis of 3 distinct contributions of forage fish worldwide
4. Mushroom-derived compound lengthens survival in dogs with cancer, Penn Vet study finds
5. Swim training plus healthy diet factor in cancer fight: New study
6. Turf study to monitor runoff, establish fertilizer management practices
7. UC Santa Cruz study shows how sea otters can reduce CO2 in the atmosphere
8. Study finds how BPA affects gene expression, anxiety; Soy mitigates effects
9. Studying sex differences in autism focus of $15 million NIH award to Yale center
10. UF Guantanamo Bay Lepidoptera study sets baseline for future research
11. Rice University researchers optimize photoluminescent probes to study DNA and more
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Study of giant viruses shakes up tree of life
(Date:6/2/2016)... -- The Department of Transport Management (DOTM) of ... US Dollar project, for the , Supply and ... and IT Infrastructure , to Decatur ... of Identity Management Solutions. Numerous renowned international vendors participated in ... was selected for the most compliant and innovative solution. ...
(Date:6/2/2016)... 2016 Perimeter Surveillance & Detection ... Physical Infrastructure, Support & Other Service  The ... offers comprehensive analysis of the global Border Security ... revenues of $17.98 billion in 2016. Now: ... leader in software and hardware technologies for advanced video ...
(Date:5/24/2016)... , May 24, 2016 Ampronix facilitates superior patient care by providing ...  3D medical LCD display is the latest premium product recently added to the range ... ... ... Sony 3d Imaging- LCD Medical Display- Ampronix News ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... 23, 2016 /PRNewswire/ - FACIT has announced the ... biotechnology company, Propellon Therapeutics Inc. ("Propellon" or ... of a portfolio of first-in-class WDR5 inhibitors for ... as WDR5 represent an exciting class of therapies, ... medicine for cancer patients. Substantial advances have been ...
(Date:6/23/2016)... MA (PRWEB) , ... June 23, 2016 , ... ... Peel Plate® YM (Yeast and Mold) microbial test has received AOAC Research Institute ... platform of microbial tests introduced last year,” stated Bob Salter, Vice President of ...
(Date:6/23/2016)... 23, 2016   EpiBiome , a precision microbiome ... in debt financing from Silicon Valley Bank (SVB). The ... to advance its drug development efforts, as well as ... "SVB has been an incredible strategic partner to ... traditional bank would provide," said Dr. Aeron Tynes ...
(Date:6/23/2016)... ... 23, 2016 , ... In a new case report published today in STEM ... who developed lymphedema after being treated for breast cancer benefitted from an injection of ... dealing with this debilitating, frequent side effect of cancer treatment. , Lymphedema ...
Breaking Biology Technology: