Featured Research

from universities, journals, and other organizations

Key To Virulence Protein Entry Into Host Cells Discovered

Date:
August 6, 2008
Source:
Virginia Tech
Summary:
Researchers from the Virginia Bioinformatics Institute at Virginia Tech have identified the region of a large family of virulence proteins in oomycete plant pathogens that enables the proteins to enter the cells of their hosts. The protein region has the ability to carry the virulence proteins across the membrane surrounding plant cells without any additional machinery from the pathogen. Once inside the plant cell, the proteins suppress the immune system of the plant allowing the infection to progress.

Researchers from the Virginia Bioinformatics Institute (VBI) at Virginia Tech have identified the region of a large family of virulence proteins in oomycete plant pathogens that enables the proteins to enter the cells of their hosts.

Related Articles


The protein region contains the amino acid sequence motifs RXLR and dEER and has the ability to carry the virulence proteins across the membrane surrounding plant cells without any additional machinery from the pathogen. Once inside the plant cell, the proteins suppress the immune system of the plant allowing the infection to progress. The work, which focused on the virulence protein Avr1b from the soybean plant pathogen Phytophthora sojae, is published in The Plant Cell.1

Oomycetes are fungal-like organisms related to marine algae that cause tens of billions of dollars of losses to agriculture, forestry and natural ecosystems every year. The oomycete Phytophthora infestans caused the Irish potato famine in the nineteenth century. Another Phytophthora species, P. ramorum, is causing Sudden Oak Death disease in California's coastal forests. P. sojae results in $200-300 million in annual losses for commercial soybean farmers in the United States and estimated annual soybean losses of $1-2 billion worldwide. All of these oomycete species contain hundreds of genes that encode for virulence proteins that have the RXLR-dEER region.2

The virulence proteins, including Avr1b, enter the soybean host where they are capable of suppressing an important process in plant immunity called programmed cell death.3 Programmed cell death is an in-built suicide mechanism that kills infected plant tissue, filling it with toxins so the pathogen can no longer feed on it. By preventing this protective mechanism in the host, the virulence proteins ensure that the pathogen can establish an unassailable foothold in the plant tissue from which the pathogen can pursue its destructive path.

Postdoctoral fellow Dr. Daolong Dou, the lead author of the article, commented: "We have suspected for a long time that these virulence proteins had some way of slipping inside plant cells to suppress immunity. Our findings finally nail down that mechanism and enable us to focus on how to block the entry mechanism."

The researchers also demonstrated that the RXLR and dEER motifs could be replaced by similar targeting sequences found in effector proteins produced by the malarial parasite Plasmodium. This hints that the targets of the effectors in the soybean and human hosts may be very ancient.

VBI Professor Brett Tyler remarked: "The finding that virulence proteins from oomycetes and the malaria parasite Plasmodium use the same entry mechanism means that we may be able to use the same or similar drugs to block infection by both groups of pathogens. This type of approach may also be relevant to other groups of pathogens, such as fungi, which we also suspect of slipping virulence proteins into host cells."

The breakthrough was enabled by an ingenious device for introducing DNA into living tissues invented by a Virginia Tech undergraduate, Shiv Kale. Kale, who has subsequently joined Dr. Tyler's research team as a graduate student, remarked: "The double-barreled Gene Gun enabled us to make much more accurate measurements of the Avr1b protein than were previously possible, which made it practicable to measure the action of the RXLR and dEER motifs." Kale was co-lead author of the article.

The research was supported by funding from the National Research Initiative of the United States Department of Agriculture's Cooperative State Research, Education and Extension Service, the National Science Foundation, the Netherlands Genomics Initiative, and the Virginia Bioinformatics Institute.


Story Source:

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


Journal References:

  1. Dou et al. RXLR-Mediated Entry of Phytophthora sojae Effector Avr1b into Soybean Cells Does Not Require Pathogen-Encoded Machinery. The Plant Cell, Online Aug 4, 2008; DOI: 10.1105/tpc.107.056093
  2. Jiang, RHY, Tripathy S, Govers F, Tyler BM. RXLR effector reservoir in two Phytophthora species is dominated by a single rapidly evolving super-family with more than 700 members. Proceedings of the National Academy of Sciences, 105(12): 4874-4879
  3. Dou et al. Conserved C-Terminal Motifs Required for Avirulence and Suppression of Cell Death by Phytophthora sojae effector Avr1b. The Plant Cell Online, 2008; 20 (4): 1118 DOI: 10.1105/tpc.107.057067

Cite This Page:

Virginia Tech. "Key To Virulence Protein Entry Into Host Cells Discovered." ScienceDaily. ScienceDaily, 6 August 2008. <www.sciencedaily.com/releases/2008/08/080804190707.htm>.
Virginia Tech. (2008, August 6). Key To Virulence Protein Entry Into Host Cells Discovered. ScienceDaily. Retrieved November 27, 2014 from www.sciencedaily.com/releases/2008/08/080804190707.htm
Virginia Tech. "Key To Virulence Protein Entry Into Host Cells Discovered." ScienceDaily. www.sciencedaily.com/releases/2008/08/080804190707.htm (accessed November 27, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Thursday, November 27, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Classic Hollywood Memorabilia Goes Under the Hammer

Classic Hollywood Memorabilia Goes Under the Hammer

Reuters - Entertainment Video Online (Nov. 26, 2014) The iconic piano from "Casablanca" and the Cowardly Lion suit from "The Wizard of Oz" fetch millions at auction. Sara Hemrajani reports. Video provided by Reuters
Powered by NewsLook.com
Pet Dogs to Be Used in Anti-Ageing Trial

Pet Dogs to Be Used in Anti-Ageing Trial

Reuters - Innovations Video Online (Nov. 26, 2014) Researchers in the United States are preparing to discover whether a drug commonly used in human organ transplants can extend the lifespan and health quality of pet dogs. Video provided by Reuters
Powered by NewsLook.com
From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

From Popcorn To Vending Snacks: FDA Ups Calorie Count Rules

Newsy (Nov. 25, 2014) The US FDA is announcing new calorie rules on Tuesday that will require everywhere from theaters to vending machines to include calorie counts. Video provided by Newsy
Powered by NewsLook.com
Feast Your Eyes: Lamb Chop Sent Into Space from UK

Feast Your Eyes: Lamb Chop Sent Into Space from UK

Reuters - Light News Video Online (Nov. 25, 2014) Take a stab at this -- stunt video shows a lamb chop's journey from an east London restaurant over 30 kilometers into space. Rough Cut (no reporter narration). 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