Featured Research

from universities, journals, and other organizations

Stressed bacteria stop growing: Mechanism discovered

Date:
August 15, 2013
Source:
University of Massachusetts Amherst
Summary:
Man, a mouse or a microbe, stress is bad. Experiments in bacteria by molecular biologists have uncovered the mechanism that translates stress, such as exposure to extreme temperature, into temporarily blocked cell growth. Bacteria deal with stress by destroying proteins needed for replication.

Scientists have uncovered the mechanism that translates stress such as exposure to extreme temperature into blocked cell growth. Stressful conditions cause some proteins to be literally bent out of shape, or misfolded, and they stop working so the cell can shift priorities to protective functions. The enzyme, Lon, helps defend against stress by cutting up and destroying small amounts of misfolded proteins. But when that enzyme encounters too many misfolded proteins, it starts destroying another perfectly fine protein, DnaA, that normally starts DNA replication.
Credit: Peter Chien, UMass Amherst

Whether a man, a mouse or a microbe, stress is bad for you. Experiments in bacteria by molecular biologists in Peter Chien's lab at the University of Massachusetts Amherst, with others at MIT, have uncovered the mechanism that translates stress, such as exposure to extreme temperature, into blocked cell growth.

It turns out that stressful conditions cause some proteins to be literally bent out of shape, or misfolded, and they stop working, says Chien. "You might think of this as microbial temper tantrums. Bacteria deal with stress by destroying proteins. Specifically, we've shown that certain kinds of bacteria respond to high temperatures by destroying proteins needed for DNA replication. Therefore, they stop growing. The signal for this destruction turned out to be the buildup of proteins that were misfolded because of the stress."

Under favorable conditions, cells strive to grow, which means initiating DNA replication. But in stressful conditions, cells must prevent the initiation of replication and instead shift their priorities to protective functions.

As Chien explains, all cells including bacteria contain a huge variety of proteins, molecules that help cells do all the chemical reactions needed for life. Shape determines what kind of functions each protein can perform. Stressful conditions cause some proteins to be misfolded and stop working, stopping growth until the cell copes with the stress. Despite decades of study, until these experiments scientists did not fully understand the molecular mechanisms that cells use to transduce information about environmental conditions to their replication machinery.

In the current issue of Cell, Jing Liu, a graduate student researcher in the Chien lab at UMass Amherst working with the Laub lab at MIT, show that in the bacteria Caulobacter, a particular enzyme, Lon, can help defend against the effects of stress by cutting up and destroying small amounts of misfolded proteins. But when that enzyme encounters too many "bent out of shape" proteins, it starts destroying another perfectly fine protein, DnaA, that normally starts the growth process, that is, DNA replication.

When DnaA was destroyed, cells stop growing. When the stress has passed, the number of misfolded proteins drops, the enzyme Lon would stop destroying the normal protein, and cells would start growing again, the authors found.

Chien says, "In this way, bacteria can respond quickly to stressful conditions, but restart again quickly. Stress and protein misfolding are a universal part of life, so understanding how simple bacteria deal with this kind of stress will help us understand how our cells do as well."

This work was funded by the National Institutes of Health, the Howard Hughes Medical Institute and the University of Massachusetts Amherst.


Story Source:

The above story is based on materials provided by University of Massachusetts Amherst. Note: Materials may be edited for content and length.


Cite This Page:

University of Massachusetts Amherst. "Stressed bacteria stop growing: Mechanism discovered." ScienceDaily. ScienceDaily, 15 August 2013. <www.sciencedaily.com/releases/2013/08/130815172202.htm>.
University of Massachusetts Amherst. (2013, August 15). Stressed bacteria stop growing: Mechanism discovered. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2013/08/130815172202.htm
University of Massachusetts Amherst. "Stressed bacteria stop growing: Mechanism discovered." ScienceDaily. www.sciencedaily.com/releases/2013/08/130815172202.htm (accessed July 31, 2014).

Share This




More Plants & Animals News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Visitors Feel Part of the Pack at Wolf Preserve

Visitors Feel Part of the Pack at Wolf Preserve

AP (July 31, 2014) Seacrest Wolf Preserve on the northern Florida panhandle allows more than 10,000 visitors each year to get up close and personal with Arctic and British Columbian Wolves. (July 31) Video provided by AP
Powered by NewsLook.com
Raw: Thousands Flocking to German Crop Circle

Raw: Thousands Flocking to German Crop Circle

AP (July 30, 2014) Thousands of people are trekking to a Bavarian farmer's field to check out a mysterious set of crop circles. (July 30) Video provided by AP
Powered by NewsLook.com
Peace Corps Pulls Workers From W. Africa Over Ebola Fears

Peace Corps Pulls Workers From W. Africa Over Ebola Fears

Newsy (July 30, 2014) The Peace Corps is one of several U.S.-based organizations to pull workers out of West Africa because of the Ebola outbreak. Video provided by Newsy
Powered by NewsLook.com
Concern Grows Over Worsening Ebola Crisis

Concern Grows Over Worsening Ebola Crisis

AFP (July 30, 2014) Pan-African airline ASKY has suspended all flights to and from the capitals of Liberia and Sierra Leone amid the worsening Ebola health crisis, which has so far caused 672 deaths in Guinea, Liberia and Sierra Leone. Duration: 00:43 Video provided by AFP
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