Degradation of host glycogen is an important factor in bacterial pathogenesis, according to the authors of a study in the January 2007 issue of Nature Structural and Molecular Biology. Alisdair Boraston and colleagues report structure-function studies of surface anchored carbohydrate binding modules -- CBMs -- from Streptococcus pneumoniae.
Humans are constantly exposed to microbes. The relationships can be mutually beneficial (symbiotic), to the benefit one partner without necessarily harming the other (commensal) or to the benefit of one partner at the expense of the other (pathogenic). Some of the factors that drive a particular host-microbial relationship in one direction or another are the kind of carbohydrates, including glycogens, expressed by the host.
S. pneumoniae is an invasive pathogen that penetrates lung cells and goes deeper into the tissue by passing from cell to cell without killing all of the cells in its path. The authors used x-ray crystallography to study the mechanism by which pathogenic streptococci target the lungs. They found that tandem CBMs from a Streptococcal enzyme may act to specifically target intracellular lung glycogen, leading to its degradation. These findings may suggest potential new therapeutic strategies that target the disruption of glycogen interaction and/or degradation as a way to treat streptococcal lung infections.
Alisdair Boraston (University of Victoria, British Columbia, Canada)
Abstract available online.
(C) Nature Structural and Molecular Biology press release.
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