Featured Research

from universities, journals, and other organizations

Bioinformatics Sheds Light On Evolutionary Origin Of Rickettsia Virulence Genes

Date:
March 19, 2009
Source:
Virginia Tech
Summary:
Scientists have revealed that genes for a specific type of molecular secretion system in Rickettsia, a structure that is linked in many cases to virulence, have been conserved over many years of evolution.

Scientists from the Virginia Bioinformatics Institute (VBI) at Virginia Tech, the University of Maryland School of Medicine, and the University of Louisville have revealed that genes for a specific type of molecular secretion system in Rickettsia, a structure that is linked in many cases to virulence, have been conserved over many years of evolution.

Related Articles


The scientists compared the gene sequences of 13 Rickettsia species to detect a highly conserved type IV secretion system. Type IV secretion systems are membrane-spanning transporters that can act as syringes that inject virulence factors into the cells of their hosts (eukaryotes). Once introduced, these virulence factors compromise the host and may result in harmful disease, for example Legionnaires' disease (Legionella pneumophila) and Q fever (Coxiella burnetii). However, these secretion systems have not been implicated in human diseases caused by Rickettsia, including epidemic typhus (R. prowazekii) and Rocky Mountain spotted fever (R. rickettsii). Type IV secretion systems are unique in their ability to transport nucleic acids and proteins into plant and animal cells. A possible role of the transporter that is not directly associated with virulence, such as DNA transfer, has been overlooked in Rickettsia.

Dr. Joseph Gillespie, a bioinformatician at the Virginia Bioinformatics Institute and leader of the study, remarked: "We have used the Rickettsia genomic information steadily accumulated over the past 10 years as a starting point to look in detail at the origin and function of Rickettsia virulence-like genes. The study reveals a highly conserved type IV secretion system across the 13 genomes investigated, some of which are, intriguingly, not known to cause disease in their invertebrate and vertebrate hosts."

In addition to the evolutionarily conserved nature of the Rickettsia type IV secretion system, informatics analysis revealed some unexpected properties, including gene duplication of nearly half of its components. Gene duplication is very rare in Rickettsia genomes. By digging a little further, the team also identified three additional genes that likely contribute to the secretion system. Gillespie noted: "Because Rickettsia live inside their hosts at all stages of their life cycle, we are very limited in how we can characterize their genes. Researchers often have little choice but to apply related information from other bacteria that are easier to study." This often entails labor-intensive manual work that cannot currently be substituted by automated gene prediction methods. "Sometimes, the brain beats the algorithm," Gillespie added.

One of the major revelations of the sequence comparison is that the ancestor organism of the Rickettsia most likely acquired a virulence-like genetic locus from distantly related bacteria. The team speculates that this may have taken place while the ancestor was residing in a protozoan host.

Principal Investigator Bruno Sobral remarked: "Virulent species of Rickettsia are of great interest both as emerging agents of infectious disease and potential bioterror agents. However, a lot of intense laboratory work has failed to provide information that characterizes their virulence factors. Our comparative genomics approach sheds light on the evolution of Rickettsia virulence and provides a solid foundation for the future laboratory assessment of the function of the Rickettsia type IV secretion system."

Dr. Gillespie concluded: "Additional experimental evidence from recent studies suggests that some of the components of the Rickettsia type IV secretion system are indeed expressed, regulated and secreted. It is too early yet to know with certainty the precise mechanism of how the system operates but we now have a solid foundation for future work."


Story Source:

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


Journal Reference:

  1. Joseph J. Gillespie, Nicole C. Ammerman, Sheila M. Dreher-Lesnick, M. Sayeedur Rahman, Micah J. Worley, João C. Setubal, Bruno S. Sobral, Abdu F. Azad. An anomalous type IV secretion system in Rickettsia is evolutionarily conserved. PLoS One, March 12, 2009 DOI: 10.1371/journal.pone.0004833

Cite This Page:

Virginia Tech. "Bioinformatics Sheds Light On Evolutionary Origin Of Rickettsia Virulence Genes." ScienceDaily. ScienceDaily, 19 March 2009. <www.sciencedaily.com/releases/2009/03/090311223432.htm>.
Virginia Tech. (2009, March 19). Bioinformatics Sheds Light On Evolutionary Origin Of Rickettsia Virulence Genes. ScienceDaily. Retrieved March 31, 2015 from www.sciencedaily.com/releases/2009/03/090311223432.htm
Virginia Tech. "Bioinformatics Sheds Light On Evolutionary Origin Of Rickettsia Virulence Genes." ScienceDaily. www.sciencedaily.com/releases/2009/03/090311223432.htm (accessed March 31, 2015).

Share This


More From ScienceDaily



More Plants & Animals News

Tuesday, March 31, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Gorilla Falls Into Zoo Moat

Gorilla Falls Into Zoo Moat

Reuters - Light News Video Online (Mar. 31, 2015) — A gorilla comes to the rescue of her sister who fell into a moat in Israel&apos;s Safari zoo. Rough cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Giant Amphibian Fossils Found in Portugal

Giant Amphibian Fossils Found in Portugal

Reuters - Light News Video Online (Mar. 31, 2015) — Scientists discover a new species of giant amphibian that was one of the largest predators on earth about 220 million year ago. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Rhino Goes on Deadly Rampage in Nepal

Rhino Goes on Deadly Rampage in Nepal

Reuters - News Video Online (Mar. 31, 2015) — A rhino runs rampant down a bustling city street, killing one woman and injuring several others, before security personnel chase it back into the forest. Vanessa Johnston reports. Video provided by Reuters
Powered by NewsLook.com
Bionic Ants Could Be Tomorrow's Factory Workers

Bionic Ants Could Be Tomorrow's Factory Workers

Reuters - Innovations Video Online (Mar. 30, 2015) — Industrious 3D printed bionic ants working together could toil in the factories of the future, says German technology company Festo. The robotic insects cooperate and coordinate their actions and movements to achieve a common aim. Amy Pollock reports. Video provided by Reuters
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:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

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