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:3/1/2017)... , March 1, 2017  Aware, Inc. (NASDAQ: ... announced that Richard P. Moberg has resigned, ... co-President and Chief Financial Officer and Treasurer of Aware ... to serve as a member of the Board of ... , Aware,s co-Chief Executive Officer and co-President, General Counsel ...
(Date:2/26/2017)... , Feb. 25, 2017  Securus Technologies, ... technology solutions for public safety, investigation, corrections and ... Recidivism and Reentry. "Too often, too ... prisons and county jails are trying to tackle ... inmates and friends and family members. While significant steps ...
(Date:2/16/2017)...  Genos, a community for personal genetic discovery ... Laboratory Accreditation from the College of American Pathologists ... that meet stringent requirements around quality, accuracy and ... "Genos is committed to maintaining the highest ... to be receiving CAP accreditation," said Jill ...
Breaking Biology News(10 mins):
(Date:3/23/2017)... 23, 2017  GlobeImmune, Inc. today announced it has ... of 12,835,490 shares of its common stock to NantCell, ... connection with the sale of its common stock, NantCell ... issue to GlobeImmune 200,000 shares, an estimated $2.0 million ... "We are pleased to enter into this strategic agreement ...
(Date:3/23/2017)... ... March 23, 2017 , ... Ellen Matloff, ... Connecticut Technology Council (CTC) as a 2017 Women of Innovation® finalist. Matloff will ... Innovation Awards Dinner. , The dinner recognizes women accomplished in science, technology, engineering ...
(Date:3/23/2017)... NetworkNewsWire Editorial Coverage  ... Cancer remains one of ... health care systems, in terms of costs and resources. However, ... the development of innovative and efficient therapies that demonstrate higher ... types of cancer treatments, a growing number of patients receiving ...
(Date:3/23/2017)... Colo. , March 23, 2017  Agriculture technology ... Series A financing and note conversion to commercialize its ... Planet is focused on developing products that are simultaneously ... $30 million in the last 18 months. This latest ... North Bridge Venture Partners. The company,s ...
Breaking Biology Technology: