Within
harsh environments like hot springs, volcanic craters and deep-sea hydrothermal
vents -- uninhabitable by most life forms -- microscopic organisms are
thriving. How? It's all in how they wrap themselves.
Stanford
University researchers
have identified a protein that helps these organisms form a protective,
lipid-linked cellular membrane -- a key to withstanding extremely highly acidic
habitats.
Scientists
had known that this group of microbes -- called archaea -- were surrounded by a
membrane made of different chemical components than those of bacteria, plants
or animals. They had long hypothesized that it could be what provides
protection in extreme habitats. The team directly proved this idea by
identifying the protein that creates the unusual membrane structure in the
species Sulfolobus acidocaldarius.
The
structures of some organisms' membranes are retained in the fossil record and
can serve as molecular fossils or biomarkers, leaving hints of what lived in
the environment long ago. Finding preserved membrane lipids, for example, could
suggest when an organism evolved and how that may have been the circumstance of
its environment. Being able to show how this protective membrane is created
could help researchers understand other molecular fossils in the future,
offering new evidence about the evolution of life on Earth.
Archaea
are sometimes called the "third domain of life," with one domain
being bacteria and the other being a group that includes plants and animals --
collectively known as eukaryotes. Archaea includes some of the oldest, most abundant
lifeforms on the planet, without which the ecosystem would collapse. Archaea
are particularly anomalous microbes, confused with bacteria one day and likened
to plants or animals the next because of their unique molecular structures.
The
research is particularly interesting because the classification for archaea is
still debated by taxonomists. They were only separated from the bacteria and
eukaryote domains in the past two decades, following the development of genetic
sequencing in the 1970s.
See:
Posted by Dr. Tim Sandle, Pharmaceutical Microbiology
