The lipid A in plant cells is evidently not toxic. The human intestine contains billions of Gram-negative bacteria, but lipid A does not become a problem unless bacteria invade the bloodstream.
"We've no idea what it's doing, but it must be something important because it's been retained for a billion years of evolution of plant chloroplasts," said Peter Armstrong, professor of molecular and cellular biology at UC Davis and senior author on the paper.
Endotoxin is better known to bacteriologists and physicians as part of the outer coat of Gram-negative bacteria such as E. coli. The lipid A core of bacterial endotoxin activates the immune system and can cause septic shock, a major cause of death from infection. It is distinct from the toxin found in E. coli strain 0157, responsible for the recent outbreak of food poisoning tied to spinach.
Bacteria were thought to be the only source of lipid A. However, R.L. Pardy, professor at the University of Nebraska-Lincoln, recently found a similar molecule in Chlorella, a single-celled relative of more advanced plants. Armstrong's lab at UC Davis developed methods to visualize lipid A in cells, using a protein from the immune system of the horseshoe crab, and the researchers began collaborating.
"It was one of those celebratory moments, when I looked in the microscope and saw these gloriously stained algal cells," Armstrong said, describing their first experiment. The group has now found lipid A in chloroplasts of garden pea plants as well as green algae, and Armstrong suspects that it is present in all higher plants with chloroplasts.
That idea is supported by genetics. Sequencing of the Arabidopsis genome -- the first higher plant to have its entire DNA sequence read -- revealed that the common lab plant has all the biochemical machinery to make lipid A, an observation that had gone largely unnoticed until now. Chloroplasts themselves are thought to have evolved from cyanobacteria, independent photosynthetic bacteria that took up residence in ancestral plant cells.
Other authors on the paper, in addition to Armstrong and Pardy, are postgraduate researcher Margaret Armstrong; Steven Theg, professor of plant biology, and graduate student Nikolai Braun at UC Davis; and Norman Wainwright at the Woods Hole Marine Biology Laboratory. The work was funded by the National Science Foundation and is published in the October 2006 issue of the FASEB Journal.
Andy Fell | EurekAlert!
Seeing on the Quick: New Insights into Active Vision in the Brain
15.08.2018 | Eberhard Karls Universität Tübingen
New Approach to Treating Chronic Itch
15.08.2018 | Universität Zürich
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur
What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...
08.08.2018 | Event News
27.07.2018 | Event News
25.07.2018 | Event News
15.08.2018 | Physics and Astronomy
15.08.2018 | Earth Sciences
15.08.2018 | Physics and Astronomy