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Bacterium digests complex sugar with new enzyme
Issue date: 11/1/07
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Complex carbohydrates are as important to living cells as are proteins and fats, but they are frequently given short shrift by biologists. Long chains of sugars, called polysaccharides, form an integral part of the external shell of bacterial cells and fungi, help cells recognize each other and participate in the attachment of cells to other surfaces.
New research from the laboratory of Saul Roseman, a professor in the Hopkins biology department who is recognized as a founder of the field of glycobiology, provides new insights into one common polysaccharide, chitin.
Chitin is the second most abundant polysaccharide in nature after cellulose, which makes up the bulk of most plants. Chitin is found in fungal cell walls and the shells of many animals, including insects and crustaceans.
It is especially abundant in marine environments. When many marine animals die, their remains must be processed or the chitin will eventually build up in quantities great enough to disrupt the marine ecosystem.
This is where bacteria such as Vibrio cholerae step in. V. cholerae causes the dreaded disease cholera in humans, but it forms an essential part of the normal marine ecosystem. The genome of V. cholerae contains a gene called cod that allows the cells to process chitin by breaking down the original moleculer chain into simpler sugars and smaller organic products.
To study exactly how V. cholerae breaks down chitin, scientists modified the cod gene to cause an over-expression of the enzyme chitinase. The team found that chitinase is only produced in the presence of chitin and other polysaccharides. They also found that the enzyme is actively secreted by the V. cholerae cells into the surrounding environment, meaning that much of the enzyme's activity actually takes place outside of the cell.
This research is important because the breakdown of chitin is an essential component of the self-regulation of marine ecosystems. The process might also form part of a communication pathway between bacteria and plant cells in the marine environment, a suggestion that comes from the study of a similar chitin metabolizing pathway. The pathways involved in chitin degradation might also influence the infectivity of V. cholerae in humans, which continues to be a worldwide medical problem.
The discoveries regarding the enzymatic properties of chitinase could have real-world applications as well. Chitin is a much more versatile molecule than many people suspect. It is useful in flocculation, the process of binding dissolved compounds to pellets that can aggregate and be filtered out.
Chitin is also used as a strengthening agent in paper-making, a delivery vehicle for pharmaceuticals, a binder for adhesives and dyes, a natural plant fertilizer and an enhancer for wound healing.
Basic research, even into the ecology of a simple bacterium, often moves in surprising directions. By better understanding the function of the chitinase pathway, scientists might be able to manipulate chitin, allowing them to use it in a variety of industrial and biomedical applications.
New research from the laboratory of Saul Roseman, a professor in the Hopkins biology department who is recognized as a founder of the field of glycobiology, provides new insights into one common polysaccharide, chitin.
Chitin is the second most abundant polysaccharide in nature after cellulose, which makes up the bulk of most plants. Chitin is found in fungal cell walls and the shells of many animals, including insects and crustaceans.
It is especially abundant in marine environments. When many marine animals die, their remains must be processed or the chitin will eventually build up in quantities great enough to disrupt the marine ecosystem.
This is where bacteria such as Vibrio cholerae step in. V. cholerae causes the dreaded disease cholera in humans, but it forms an essential part of the normal marine ecosystem. The genome of V. cholerae contains a gene called cod that allows the cells to process chitin by breaking down the original moleculer chain into simpler sugars and smaller organic products.
To study exactly how V. cholerae breaks down chitin, scientists modified the cod gene to cause an over-expression of the enzyme chitinase. The team found that chitinase is only produced in the presence of chitin and other polysaccharides. They also found that the enzyme is actively secreted by the V. cholerae cells into the surrounding environment, meaning that much of the enzyme's activity actually takes place outside of the cell.
This research is important because the breakdown of chitin is an essential component of the self-regulation of marine ecosystems. The process might also form part of a communication pathway between bacteria and plant cells in the marine environment, a suggestion that comes from the study of a similar chitin metabolizing pathway. The pathways involved in chitin degradation might also influence the infectivity of V. cholerae in humans, which continues to be a worldwide medical problem.
The discoveries regarding the enzymatic properties of chitinase could have real-world applications as well. Chitin is a much more versatile molecule than many people suspect. It is useful in flocculation, the process of binding dissolved compounds to pellets that can aggregate and be filtered out.
Chitin is also used as a strengthening agent in paper-making, a delivery vehicle for pharmaceuticals, a binder for adhesives and dyes, a natural plant fertilizer and an enhancer for wound healing.
Basic research, even into the ecology of a simple bacterium, often moves in surprising directions. By better understanding the function of the chitinase pathway, scientists might be able to manipulate chitin, allowing them to use it in a variety of industrial and biomedical applications.
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