www.czu.cz ; www.usab-tm.ro ; www.raupp.info

In a recent study published in the Journal of Biological Chemistry,
scientists report on the discovery of a new molecule that is essential for
degradation of the biopolymer chitin. This new molecule could eventually aid
in the engineering of fungi-resistant plants and could also lead to the
discovery of similar molecules that can be used in cellulose-based biofuel
production, August 2005.

The research appears as the "Paper of the Week" in the August 2005 issue
of the Journal of Biological Chemistry, an American Society for Biochemistry
and Molecular Biology journal.

"Chitin is an insoluble molecule that consists of tightly packed chains of
polymerized sugars," explains study author Dr. Vincent G. H. Eijsink of the
Norwegian University of Life Sciences. "It is synthesized by different
crustaceans, mollusks, algae, insects, fungi and yeasts and is a major
structural component of these organisms. For example, chitin gives strength
and stiffness to the shells/cuticles of shrimps and insects and to the cell
walls of fungi. Because chitin is an abundant resource and, most
importantly, because it occurs in several types of plague organisms and
parasites, chitin degradation is of great interest to humanity. For example,
insects might be combated by interfering with their chitin metabolism.
Insect viruses need to degrade insect chitin for infection. Fungi may also
be combated by degrading the chitin in their cell walls."

More than one billion tons of chitin are produced by insects, fungi, and
marine organisms every year. Despite this abundant production, chitin does
not accumulate in most ecosystems, indicating that the molecule is somehow
degraded. Many aquatic and terrestrial microorganisms produce enzymes called
chitinases which are responsible for breaking down chitin. Because chitin is
a very tough molecule, chitinases have quite a challenge. In order to break
the bonds between the sugar units, they must gain access to the bonds by
somehow disrupting the packing of the sugar chains in the chitin molecule.
How exactly chitinases overcome these challenges has been unclear until now.

Interested in learning more about how the breakdown of chitin occurs, Dr.
Eijsink and his colleagues investigated chitin degradation by the soil
bacterium Serratia marcescens. They discovered that in addition to producing
chitinases, the bacterium also make a protein called CBP21 which binds to
and disrupts the chitin polymer making it more accessible to degradation by
chitinases. They showed that adding CBP21 dramatically speeds up the
degradation of chitin by chitinases. CBP21 works by binding to chitin
through highly specific interactions that disrupt the chitin structure
making the individual sugar chains in the chitin polymer more amenable to
enzymatic degradation.

The discovery of this new protein that participates in chitin degradation
has many potential applications. For example, transgenic plants that
expresses both chitinases and CBP21 would be able to combat fungi by
degrading chitin in their cell walls. And, a better understanding of natural
chitin turnover increases our ability to interfere with chitin metabolism in
insects and other plague organisms.

CBP21 also has the potential to aid in the production of biofuel. "In
principle, large quantities of chitin are available for exploration,
primarily due to fishing and farming of crustaceans such as shrimps," says
Dr. Eijsink. "However, a current lack of technology limits the exploitation
of these waste streams. CBP21-like proteins may become an important tool for
effective, enzymatic processing of this valuable resource. More in general,
one might say that our discovery may lead to discovery of proteins with
similar functions in cellulose processing. This may be of major important
for the cellulose field and production of biofuel."

[www.rednova.com]

------------------------------------------
Posted to Phorum via PhorumMail