Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New discovery blurs distinction between human cells and those of bacteria

10.08.2005


UCLA biochemists reveal the first structural details of a family of mysterious objects called microcompartments that seem to be present in a variety of bacteria. The discovery was published Aug. 5 in the journal Science.



"This is the first look at how microcompartments are built, and what the pieces look like," said Todd O. Yeates, UCLA professor of chemistry and biochemistry, and a member of the UCLA-DOE Institute of Genomics and Proteomics. "These microcompartments appear to be highly evolved machines, and we are just now learning how they are put together and how they might work. We can see the particular amino acids and atoms."

A key distinction separating the cells of primitive organisms like bacteria, known as prokaryotes, from the cells of complex organisms like humans is that complex cells -- eukaryotic cells -- have a much higher level of subcellular organization; eukaryotic cells contain membrane-bound organelles, such as mitochondria, the tiny power generators in cells. Cells of prokaryotes have been viewed as very primitive, although some contain unusual enclosures known as microcompartments, which appear to serve as primitive organelles inside bacterial cells, carrying out special reactions in their interior.


"Students who take a biology class learn in the first three days that cells of prokaryotes are uniform and without organization, while cells of eukaryotes have a complex organization," Yeates said. "That contrast is becoming less stark; we are learning there is more of a continuum than a sharp divide. These microcompartments, which resemble viruses because they are built from thousands of protein subunits assembled into a shell-like architecture, are an important component of bacteria. I expect there will be a much greater focus on them now."

Yeates’ Science paper reveals the first structures of the proteins that make up these shells, and the first high-resolution insights into how they function.

"Those microcompartments have remained shrouded in mystery, largely because of an absence of a detailed understanding of their architecture, of what the structures look like," said Yeates, who also is a member of the California NanoSystems Institute and UCLA’s Molecular Biology Institute. "The complete three-dimensional structure is still unknown, but in this paper we have provided the first three-dimensional structure of the building blocks of the carboxysome, a protein shell which is the best-studied microcompartment."

The UCLA biochemists also report 199 related proteins that presumably do similar things in 50 other bacteria, Yeates said.

"Our findings blur the distinction between eukaryotic cells and those of prokaryotes by arguing that bacterial cells are more complex than one would imagine, and that many of them have evolved sophisticated mechanisms," Yeates said.

While microcompartments have been directly observed in only a few organisms, "surely there will be many more," Yeates said. "The capacity to create subcellular compartments is very widespread across diverse microbes. We believe that many prokaryotes have the capacity to create subcellular compartments to organize their metabolic activities."

Yeates’ research team includes research scientist and lead author Cheryl Kerfeld; Michael Sawaya, a research scientist with UCLA and the Howard Hughes Medical Institute; Shiho Tanaka, a former UCLA undergraduate who is starting graduate work at UCLA this fall in biochemistry; and UCLA chemistry and biochemistry graduate student Morgan Beeby.

The structure of the carboxysome shows a repeating pattern of six protein molecules packed closely together.

"We didn’t know six would be the magic number," Yeates said. "What surprises me is how nearly these six protein molecules fill the space between them. If you take six pennies and place them in the shape of a ring, that leaves a large space in the middle. Yet the shape of this protein molecule is such that when six proteins come together, they nearly fill the space; what struck me is how tightly packed they are. That tells us the shell plays an important role in controlling what comes in and goes out. When we saw how the many hexagons come together, we saw that they filled the space tightly as well."

The UCLA biochemists determined the structures from their analysis of small crystals, using X-ray crystallography. How microcompartments fold into their functional shapes remains a mystery.

Yeates’ laboratory will continue to study the structures of microcompartments from other organisms.

If microcompartments can be engineered, biotechnology applications potentially could arise from this research, Yeates said.

Stuart Wolpert | EurekAlert!
Further information:
http://www.college.ucla.edu

More articles from Life Sciences:

nachricht Too much of a good thing: overactive immune cells trigger inflammation
16.09.2019 | Universität Basel

nachricht The sleep neuron in threadworms is also a stop neuron
16.09.2019 | Goethe-Universität Frankfurt am Main

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Tomorrow´s coolants of choice

Scientists assess the potential of magnetic-cooling materials

Later during this century, around 2060, a paradigm shift in global energy consumption is expected: we will spend more energy for cooling than for heating....

Im Focus: The working of a molecular string phone

Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Potsdam (both in Germany) and the University of Toronto (Canada) have pieced together a detailed time-lapse movie revealing all the major steps during the catalytic cycle of an enzyme. Surprisingly, the communication between the protein units is accomplished via a water-network akin to a string telephone. This communication is aligned with a ‘breathing’ motion, that is the expansion and contraction of the protein.

This time-lapse sequence of structures reveals dynamic motions as a fundamental element in the molecular foundations of biology.

Im Focus: Milestones on the Way to the Nuclear Clock

Two research teams have succeeded simultaneously in measuring the long-sought Thorium nuclear transition, which enables extremely precise nuclear clocks. TU Wien (Vienna) is part of both teams.

If you want to build the most accurate clock in the world, you need something that "ticks" very fast and extremely precise. In an atomic clock, electrons are...

Im Focus: Graphene sets the stage for the next generation of THz astronomy detectors

Researchers from Chalmers University of Technology have demonstrated a detector made from graphene that could revolutionize the sensors used in next-generation space telescopes. The findings were recently published in the scientific journal Nature Astronomy.

Beyond superconductors, there are few materials that can fulfill the requirements needed for making ultra-sensitive and fast terahertz (THz) detectors for...

Im Focus: Physicists from Stuttgart prove the existence of a supersolid state of matte

A supersolid is a state of matter that can be described in simplified terms as being solid and liquid at the same time. In recent years, extensive efforts have been devoted to the detection of this exotic quantum matter. A research team led by Tilman Pfau and Tim Langen at the 5th Institute of Physics of the University of Stuttgart has succeeded in proving experimentally that the long-sought supersolid state of matter exists. The researchers report their results in Nature magazine.

In our everyday lives, we are familiar with matter existing in three different states: solid, liquid, or gas. However, if matter is cooled down to extremely...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Society 5.0: putting humans at the heart of digitalisation

10.09.2019 | Event News

Interspeech 2019 conference: Alexa and Siri in Graz

04.09.2019 | Event News

AI for Laser Technology Conference: optimizing the use of lasers with artificial intelligence

29.08.2019 | Event News

 
Latest News

Too much of a good thing: overactive immune cells trigger inflammation

16.09.2019 | Life Sciences

Scientists create a nanomaterial that is both twisted and untwisted at the same time

16.09.2019 | Materials Sciences

Researchers have identified areas of the retina that change in mild Alzheimer's disease

16.09.2019 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>