|COOK GREGORY M - CORNELL UNIVERSITY
|SAIER MILTON H - UNIV. OF CA, SAN DIEGO
Submitted to: Journal of Bacteriology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/1995
Publication Date: N/A
Interpretive Summary: Streptococcus bovis is a predominant bacterium in the rumen of ruminant farm animals (cattle, sheep, goats). It is an opportunistic bacterium that outgrows other bacteria in the rumen and the colon when there is an abundance of carbohydrate. This overgrowth causes acute indigestion, ruminal acidosis, and even the death of cattle. In humans, S. bovis has been implicated in the etiology of colon cancer. We undertook research to study the regulation of carbohydrate uptake by S. bovis and found that it had a regulatory mechanism called "inducer expulsion". S. bovis has a preference for the sugar, glucose, and glucose addition causes the expulsion of another sugar, lactose, from the cell. In S. bovis, inducer expulsion seems to be regulated by the binding of a specific enzyme, a sugar phosphate phosphatase, to the cell membrane. Information on the regulation of carbohydrate utilization may provide ways of inhibiting S. bovis, alleviating ruminal acidosis, improving the efficiency of animal production and decreasing colon cancer.
Technical Abstract: Streptococcus bovis has a sugar phosphate phosphatase that hydrolyzes methyl-B-D-thigalactopyranoside-6-phosphate (TMG-6-phosphate), thereby initiating TMG expulsion. Synthesis of the phosphatase is induced by lactose, and the enzyme is sequestered in an inactive form by interaction with a component of the cell membrane. Because membranes of glucose-grown cells did not bind or inhibit the phosphatase, binding may be a key regulatory element of inducer expulsion.