Did viruses precede other life?
Structural studies on ancient virus reveal clues about the evolution of life
on Earth
By Cathy Holding

Viruses share a common ancestor that existed over 3 billion years ago and
may even have preceded cellular forms of life, according to a report in the
May 3 PNAS by George Rice and colleagues at Montana State University.

Based on a comparison of known virus types and an icosahedral virus isolated
from a hot spring in Yellowstone National Park, the team found that coat
proteins in all viral types that inhabit the three domains of life-Eukarya,
Bacteria, and Archaea-have conformational similarities even though the
genetics underlying them is quite different.

Nearly all of the Yellowstone virus' 36 predicted open reading frame
products showed no significant similarity to proteins in public databases,
and so basic structural and assembly principles in this virus were compared
instead, revealing an "astounding" similarity with all virus types,
according to the authors.

"This suggests that this type of coat protein arrangement preceded the split
of the three domains of life over 3 billion years ago," Mark A. Young, the
team's leader and coauthor of the paper, told The Scientist.

Read the rest at The Scientist.com
http://www.biomedcentral.com/news/20040506/01

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