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LMS Issue 2 | 2014
News | International & Local
Immune System Enzyme in 3D
A
group of scientists at Princeton
University have made a major
discovery, which could help in the
fight against infectious diseases. Alexei
Korennykh, leader on the study, and her
colleagues have successfully revealed
the three-dimensional (3D) structure
of an enzyme that plays a vital role in
the body’s innate immune response
system. Their paper was published in the
February edition of the journal Science.
Ribonulease L (RNase L) is an enzyme
that is an important component of the
body’s initial immune response to an
invasion by foreign particles. However,
up until now the exact structure of
this enzyme was unknown. Assistant
Professor of Molecular Biology, Korennykh and her fellow scientists have
made a breakthrough in this regard
by uncovering the 3D structure of this
enzyme. This finding could prove to
be extremely valuable in the future of
medical research, specifically cancer
research.
RNase L is responsible for destroying
the genetic material (RNA) of invading
viruses, as well as defending against
invading bacteria. Thus, understanding
the components of this molecule could
aid researchers in understanding the
effects of carcinogenic mutations in the
RNase L gene.
For instance, families with hereditary
prostate cancers often carry genetic
mutations in the locus that codes for
RNase L. Thus, the 3D structure of this
enzyme could reveal the positions of
these mutations and explain why some
of these mutations lead to cancer.
To discover the enzyme’s structure,
the researchers first created a crystal
of RNase L with the right combination
of chemical treatments that would
force the enzyme to crystallise without
destroying it.
Then these crystals were bombarded
with powerful X-rays that diffract when
they hit the atoms in the crystal and
form patterns indicative of the crystal’s
structure.
Thus, these patterns revealed the 3D
arrangement of the RNase L atom. These
same patterns were then found in the
human RNase L enzyme.
The scientists found that each RNase L
enzyme consists of two nearly identical
subunits called protomers. While the
one protomer finds and attaches to
the RNA, the other protomer snips it.
The initial protomer latches onto one of
the four ‘letters’ that make up the RNA
code, in particular, the ‘U’, which stands
for a component of RNA called uridine.
The other protomer ‘counts’ RNA letters
starting from the U, skips exactly one
letter and cuts the RNA.
This insightful discovery could have
a great impact on medical research in
the futu ɔ