April 18, 2005
Biologist Melissa Jurica earns prestigious
grant from Searle Scholars Program
By Tim Stephens
The Searle Scholars Program has awarded Melissa Jurica, assistant
professor of molecular, cell, and developmental biology, a three-year,
$240,000 grant to support her research. Jurica, who studies
the complex system by which human cells process genetic information,
is one of just 15 young scientists awarded the prestigious grants
Melissa Jurica's research focuses
on a tiny molecular machine known as the spliceosome.
The Searle Scholars Program makes grants to selected universities
and research centers to support the independent research of
exceptional young faculty in the biomedical sciences.
This is the first year that UCSC has been invited to participate
in the program. Jurica, who joined the UCSC faculty in 2003,
is the campus's first Searle Scholar.
Jurica's research focuses on a tiny molecular machine known
as the spliceosome, which edits the genetic code before the
code gets translated into the protein molecules that carry out
a vast range of biological functions.
"It's like when you shoot a movie and you don't need
all the footage, you cut some parts out and splice together
the parts you want. That's what the spliceosome does with gene
sequences," Jurica said.
Most people are familiar with the idea of genes as DNA sequences
in the chromosomes. The genetic information in a gene is encoded
in the sequence of chemical building blocks (As, Cs, Gs, and
Ts) in the linear DNA molecule. When a gene is active, its DNA
sequence gets copied into an RNA messenger, but the information
there isn't actually ready to be used--it needs to be edited
before it can direct the synthesis of proteins.
"RNA splicing is absolutely necessary for gene expression,
and there are cancers and other diseases associated with problems
in splicing," Jurica said.
In some cases, the same gene sequence can be edited in different
ways, so that one gene can produce a variety of different protein
molecules. This phenomenon, known as "alternative splicing,"
is especially common in humans. It is the primary explanation
for the surprisingly small number of genes scientists have been
able to identify in the complete human genome sequence.
The spliceosome is the key to understanding how the body's
cells control the process of alternative splicing to ensure
that the right protein gets made at the right place and time.
But the spliceosome is extraordinarily complex and difficult
to study. It is composed of more than 100 different proteins
and several different RNA molecules that come together to form
a highly dynamic and complicated structure.
The assembled spliceosome is about one millionth of an inch
in diameter. Jurica is using several techniques to study the
structure of the spliceosome, including electron microscopy
and x-ray crystallography. She is also using biochemical techniques
to investigate how the spliceosome is assembled from smaller
components and how it carries out its functions.
Jurica is affiliated with UCSC's Center for Molecular Biology
of RNA, where she is able to consult and collaborate with scientists
involved in similar research. For example, Manuel Ares, professor
of molecular, cell, and developmental biology, studies RNA splicing
in yeast, focusing in part on the effects of mutations and environmental
changes on the regulation of alternative splicing. Harry Noller,
Sinsheimer Professor of Molecular Biology and director of the
RNA Center, has used x-ray crystallography to determine the
structure of the ribosome, another complex molecular machine,
which carries out protein synthesis.
"The collaborative environment of the RNA Center makes
it a good place to do structural biology on the spliceosome.
There are great structural biologists and splicing experts here,"
The Searle Scholars Program was established at the Chicago
Community Trust in 1980. It is funded from the estates of Mr.
and Mrs. John G. Searle. Mr. Searle was the grandson of the
founder of the pharmaceutical company G. D. Searle & Company.
It was Mr. Searle's wish that certain funds be used to support
research in medicine, chemistry, and biology. To achieve this
goal, grants are made to selected academic institutions to support
the independent research of outstanding individuals who are
in the first or second year of their first appointment at the
assistant professor level, and whose current appointment is
a tenure-track position.
Email this story
Return to Front Page