Featured Research

from universities, journals, and other organizations

Discoveries Made About Cellular Reaction Processes From Ancient Life

Date:
August 5, 2003
Source:
Virginia Tech
Summary:
Researchers in Robert H. White's group at Virginia Tech are tracing the family tree of life on earth by tracing the biochemical mechanisms within the cell -- specifically those that are used in the formation of peptide bonds.

Blacksburg, Va. (Aug. 4, 2003) -- How did life begin? What chemical combination launched the first organism with self-contained metabolism? And then what happened? Researchers in Robert H. White's group at Virginia Tech are tracing the family tree of life on earth by tracing the biochemical mechanisms within the cell -- specifically those that are used in the formation of peptide bonds. The building blocks of enzymatic and functional structures in living organisms are proteins created by linking amino acids into peptides (sub units of proteins). The mechanisms for creating peptides in proteins and some coenzymes are the clues that White and colleagues are following. "Enzymes that mechanistically do the same thing are included into a family, and we believe that there is an ancestral enzyme for this family," says David Graham, who was an NSF postdoctoral fellow in microbial biology at Virginia Tech.

In their attempt to reconstruct biochemical history, White's group has discovered two enzymes in Methanococcus jannaschii that may predate the cell's use of ribosome to build proteins. Their research will be reported in the Proceedings of the National Academy of Science (PNAS) by Hong Li, a post doc at Virginia Tech; Huimin Xu, a Virginia Tech technician, Graham, now at the University of Texas at Austin, and White, professor of biochemistry. The article (#3391), "Glutathione synthetase homologs encode a-L-glutamate ligases for methanogenic coenzyme F420 and tetrahydrosarcinapterin biosyntheses," will be published in the PNAS online Early Edition during the week of Monday, Aug. 4 – Friday, Aug. 8, 2003.

"We found two enzymes, MptN and CofF, which are descendants of the ATP-grasp superfamily," says White.

The ATP superfamily is a group of enzymes that use ATP -- the nucleotide energy source for the cell. "ATP-grasp" refers to a shared nucleotide-binding method. Every self-sustaining, living organism has ATP superfamily enzymes. "We are interested in determining the functions of genes and how coenzymes are made," says Graham.

The two newly discovered genes share a common ancestor with the ribosomal protein S6:glutamate ligase and a putative a-aminoadipate ligase, defining the first group of ATP-grasp enzymes with a shared amino acid substrate specificity.

"Most people learn in high school biology about ribosomes' role in making protein, but there is a whole other world without ribosomes - interesting predecessors to how peptides were formed before ribosomes," says Graham.

White's group studies archaea, one of the earliest forms of life -- from when the earth was hot and soupy. Archaea are now found in such places as ocean vents and camel guts. "We are looking at present metabolism to extrapolate to ancient life," says White.

"MptN and CofF both produce alpha glutamate bonds (the same as in proteins), so we infer that an ancestor protein was also making alpha glutamate bonds," says Graham. "The mechanism is the same, but the substrate that the glutamate is attaching to is really different."

The compounds range from a protein to a small molecule, says White.

"We have defined a family that shares the same ability to add alpha glutamate," says Graham. "But we don't know why, yet."

Li also discovered another enzyme, CofE, which may predate ribosome. It makes gamma-linked glutamate bonds. Her article, "CofE catalyzes the addition of two glutamates to F420-0 in F420 coenzyme biosynthesis in Methanococcus jannaschii" is forthcoming in the journal Biochemistry.

"Our initial interest in how F420 is made led to discovery of one new enzyme in sarcinpterin and two enzymes in F420 that are mechanistically related. They all have glutamate in their chemical structure and share a common reaction method for adding this amino acid," says White. "This work has shown how changes in members of a superfamily of enzymes can lead to a wider diversity in their function - in this case the biosynthesis of coenzymes."

After millions of years, the genealogy of life is more like a spider web, White says. "You never know where you will end up, which makes it exciting. We are working on one spoke of the spider web and want to go back to the center.

"In the meantime, we have expanded our knowledge of gene function, which is a central goal of our work."

The reviewers of the PNAS article commented that the research increased the understanding of the ATP superfamily and appreciated the elucidation of the relationships between two members in terms of coenzyme biosynthesis.

Li received her Ph.D. in biochemistry from Virginia Tech in May 2002 and plans to continue her research.


Story Source:

The above story is based on materials provided by Virginia Tech. Note: Materials may be edited for content and length.


Cite This Page:

Virginia Tech. "Discoveries Made About Cellular Reaction Processes From Ancient Life." ScienceDaily. ScienceDaily, 5 August 2003. <www.sciencedaily.com/releases/2003/08/030805072417.htm>.
Virginia Tech. (2003, August 5). Discoveries Made About Cellular Reaction Processes From Ancient Life. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2003/08/030805072417.htm
Virginia Tech. "Discoveries Made About Cellular Reaction Processes From Ancient Life." ScienceDaily. www.sciencedaily.com/releases/2003/08/030805072417.htm (accessed September 2, 2014).

Share This




More Plants & Animals News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

We've Got Mites Living In Our Faces And So Do You

We've Got Mites Living In Our Faces And So Do You

Newsy (Aug. 30, 2014) A new study suggests 100 percent of adult humans (those over 18 years of age) have Demodex mites living in their faces. Video provided by Newsy
Powered by NewsLook.com
Washington Wildlife Center Goes Nuts Over Baby Squirrels

Washington Wildlife Center Goes Nuts Over Baby Squirrels

Reuters - US Online Video (Aug. 30, 2014) An animal rescue in Washington state receives an influx of orphaned squirrels, keeping workers busy as they nurse them back to health. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Experimental Ebola Drug ZMapp Cures Lab Monkeys Of Disease

Experimental Ebola Drug ZMapp Cures Lab Monkeys Of Disease

Newsy (Aug. 29, 2014) In a new study, a promising experimental treatment for Ebola managed to cure a group of infected macaque monkeys. Video provided by Newsy
Powered by NewsLook.com
Killer Amoeba Found in Louisiana Water System

Killer Amoeba Found in Louisiana Water System

AP (Aug. 28, 2014) State health officials say testing has confirmed the presence of a killer amoeba in a water system serving three St. John the Baptist Parish towns. (Aug. 28) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins