[Homestead] Tooth loss due to P Gingivalis
tvoivozhd
tvoivozd at infionline.net
Wed Feb 9 08:49:18 EST 2005
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/Source:/ *University Of Florida Health Science Center*
/Date:/ 2005-02-09
/URL:/ http://www.sciencedaily.com/releases/2005/02/050205123823.htm
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UF Researchers Map Bacterial Proteins That Cause Tooth Loss
The human mouth teems with millions of enamel-eroding, gum-inflaming
microbes.
One of these, Porphyromonas gingivalis, is a bacterial homesteader that
stakes a claim deep within the spaces between teeth and gums. It’s also
the leading cause of tooth loss — secreting proteins that destroy the
soft tissues and bone that support teeth to cause periodontal disease.
Now scientists have identified the thousands of proteins the bacterium
produces, shedding light on how it interacts with healthy cells in order
to thrive, according to dental researchers from the University of
Florida and the University of Washington. They describe their findings
in the current issue of the journal Proteomics.
“Determining which proteins are expressed in greater levels in the mouth
has allowed us to gain clues as to how P. gingivalis might be causing
disease, and what we might be able to do with drugs or vaccines to
prevent it,” said Richard Lamont, Ph.D., a professor of oral biology at
UF’s College of Dentistry and study investigator.
The National Institute of Dental and Craniofacial Research estimates 80
percent of adult Americans have some form of periodontal disease, their
symptoms ranging from mild gum irritation to complete tooth loss.
People with periodontal disease also are at increased risk of stroke and
heart attack, and the disease makes it difficult to control blood sugar
levels in people with diabetes. If that’s not bad enough, pregnant women
with periodontal disease are seven times more likely to deliver
low-birth-weight, preterm babies. Proteins are important to study
because they are the foundation of the cellular structure of every
living organism, Lamont said. They carry on the day-to-day biology of
life, going about their business as enzymes and antibodies. They can
also cause disease.
“The genes themselves are only important in that they encode the
proteins,” Lamont said. “It’s the proteins that are most responsible for
disease, and in most cases it’s proteins that are vaccine and drug targets.”
The scientists have been trying to understand how P. gingivalis
interacts with healthy oral tissues to cause such devastation. In this
study, they used cutting-edge molecular research techniques to map all
the proteins — known as the proteome — produced by P. gingivalis.
Ultimately, the researchers were able to fill hundreds of gaps in the
organism’s sequence of roughly 2,000 proteins.
“The approach used in this study is very exciting,” said Hansel
Fletcher, Ph.D., an associate professor of microbiology and molecular
genetics at Loma Linda University in Loma Linda, Calif. “For the first
time, we are able to see that the more than 200 so-called ‘hypothetical’
proteins in P. gingivalis are expressed and have specific functions.”
Until now, scientists had identified less than 2 percent of the
pathogen’s proteins and had to guess at what other proteins might be
present in the proteome based on similarities to other known proteins,
said Fletcher.
“This study has done two things to advance that,” Lamont said. “We’ve
identified the complete protein complement of the organism, and we’ve
looked at how those proteins are expressed when the organism is in an
environment that closely mimics an oral situation.”
To do this, Lamont and his colleagues compared the proteins secreted by
P. gingivalis when grown in a medium containing human gum cell proteins
with the proteins produced by the bacteria when grown in a neutral
medium. Bacterial proteins from the two conditions were separated using
a new technique called Multidimensional Protein Identification
Technology, or MudPIT.
Once separated, mass spectrometry was used to measure each protein’s
mass and charge, identifiers as unique to proteins as the whorls of
fingerprints are to people.
The spectrometry measurements were fed into a computer database to
create a computational model of the P. gingivalis proteome, resulting in
a surprising find.
“Some of the proteins we previously thought were important when they
were expressed in the lab proved not to be when the organism is in an
environment that mimics the oral cavity,” Lamont said.
To put it simply, the behavior, or protein expression, of the organism
when it’s at work in the human mouth is very different from its behavior
when it’s vacationing in a Petri dish.
“An organism growing in a lab isn’t causing disease,” Lamont said. “It’s
an organism that’s in your gums, your lungs, your heart valves, your
arteries causing disease.”
The next step will be to expose P. gingivalis to other oral pathogens to
determine what interactions may exist that contribute to infection, he said.
“This study is important in that we now have an understanding of the
protein expression on a global scale for this pathogen,” Lamont said.
“Now we need to see how it adapts to various situations present in the
mouth to cause disease.”
*Editor's Note:* The original news release can be found here
<http://news.health.ufl.edu/stories/2005/Feb/Gingivalis.shtml>.
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/This story has been adapted from a news release issued by University Of
Florida Health Science Center./
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