Sneaky bacteria change
key protein’s shape to
Every once in a while in the United States,
bacterial meningitis seems to crop up out of
nowhere, claiming a young life. Part of the
disease’s danger is the ability of the bacteria
to evade the body’s immune system, but scientists are now figuring out how the pathogen hides in plain sight. Their findings, which
could help defeat these bacteria and others
like it, appear in the Journal of the American
Linda Columbus and colleagues explain that the bacteria
Neisseria meningitidis, one cause of meningitis, and its cousin
Neisseria gonorrhoeae, which is responsible for gonorrhea,
enter human cells through the receptor-mediated engulfment
triggered by Opa proteins. Gonorrhea can be cured, though one
type of the responsible bacteria has reached “superbug” status,
becoming resistant to known drugs. If meningitis is not treated
immediately with antibiotics, it can cause severe disability
and death. In a search for new ways to treat these diseases,
researchers are looking more closely at how the bacteria navigate the body undetected. When someone gets an infection,
antigens that stud the pathogen’s outer layer usually trigger
the immune system. But these two kinds of Neisseria
bacteria can elude the body’s defense cells, and Columbus’s team
wanted to know how.
They combined two approaches to figure out the architecture of one of the bacteria’s outer proteins that help it gain
entry into human cells. They found that the protein’s outer
loops interact with each other weakly, causing their structure to constantly change. This shape-shifting makes for a
kind of camouflage that hides them from the host’s immune
responses, at the same time preserving their ability to bind to
and enter a person’s cells. This deeper understanding could
help lead to new treatments for bacterial diseases.
Read more about the research: “Structure of the Neisserial
Outer Membrane Protein Opa60: Loop Flexibility Essential to
Receptor Recognition and Bacterial Engulfment,” J. Am. Chem.
Soc., May 9, 2014 (Web).
Key chocolate ingredients could
help prevent obesity, diabetes
Improved thinking. Decreased appetite. Lowered blood
pressure. The potential health benefits of dark chocolate
keep piling up, and researchers are now coming closer
to understanding what ingredients in chocolate might
help prevent obesity, as well as type 2 diabetes. They
found that one particular type of antioxidant in cocoa
prevented laboratory mice from gaining excess weight
and lowered their blood sugar levels. The report appears in
ACS’s Journal of Agricultural and Food Chemistry.
Andrew P. Neilson and colleagues explain that cocoa, the basic ingredient of
chocolate, is one of the most flavonol-rich foods around. That’s good for chocolate lovers because previous research has shown that flavonols in other foods
such as grapes and tea can help fight weight gain and type 2 diabetes. But
not all flavonols, which are a type of antioxidant, are created equal. Cocoa has
several different kinds of these compounds, so Neilson’s team decided to tease
them apart and test each individually for health benefits.
The researchers fed groups of mice different diets, including high-fat and
low-fat diets, and high-fat diets supplemented with different kinds of flavonols.
They found that adding one particular set of these compounds, known as oligomeric procyanidins (PCs), to the food made the biggest difference in keeping the
mice’s weight down if they were on high-fat diets. They also improved glucose
tolerance, which could potentially help prevent type 2 diabetes. “Oligomeric
PCs appear to possess the greatest antiobesity and antidiabetic bioactivities of
the flavonols in cocoa, particularly at the low doses employed for the present
study,” the researchers state.
Read more about the research: “Oligomeric Cocoa Procyanidins Possess
Enhanced Bioactivity Compared to Monomeric and Polymeric Cocoa Procyanidins for Preventing the Development of Obesity, Insulin Resistance, and
Impaired Glucose Tolerance during High-Fat Feeding,” J. Agric. Food Chem.,
2014, 62( 10), pp 2216–2227.
COMPILED BY JESSICA ROBERTS
Source: ACS Office of Public Affairs Weekly PressPac, www.acs.org/content/acs/en/pressroom.html