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Regulation of carbon and electron flow in Propionispira arboris: Relationship of catabolic enzyme levels to carbon substrates fermented during propionate formation via the methylmalony coenzyme a pathway

Journal Article · · Journal of Bacteriology; (USA)
OSTI ID:7165151
 [1];  [2]
  1. Univ. of Wisconsin, Madison (USA)
  2. Michigan State Univ., East Lansing (USA)

A detailed study of the glucose fermentation pathway and the modulation of catabolic oxidoreductase activities by energy sources (i.e., glucose versus lactate of fumarate) in Propionispira arboris was performed. {sup 14}C radiotracer data show the CO{sub 2} produced from pyruvate oxidation comes exclusively from the C-3 and C-4 positions of glucose. Significant specific activities of glyceraldehyde-3-phosphate dehydrogenase and fructose-1,6-bisphosphate aldolase were detected, which substantiates the utilization of the Embden-Meyerhoff-Parnas path for glucose metabolism. The methylmalonyl coenzyme A pathway for pyruvate reduction to propionate was established by detection of significant activities of methylmalonyl coenzyme A transcarboxylase, malate dehydrogenase, and fumarate reductase in cell-free extracts and by {sup 13}C nuclear magnetic resonance spectroscpic demonstation of randomization of label from (2-{sup 13}C)pyruvate into positions 2 and 3 of propionate. The specific activity of pyruvate-ferredoxin oxidoreductase, malate dehydrogenase, fumarate reductase, and transcarboxylase varied significantly in cells grown on different energy sources. D-Lactate dehydrogenase (non-NADH linked) was present in cells of P. arboris grown on lactate but not in cells grown on glucose or fumarate. These results indicate that growth substrates regulate synthesis of enzymes specific for the methylmalonyl coenzyme A path initial substrate transformation.

DOE Contract Number:
FG02-85ER13376
OSTI ID:
7165151
Journal Information:
Journal of Bacteriology; (USA), Journal Name: Journal of Bacteriology; (USA) Vol. 170:9; ISSN JOBAA; ISSN 0021-9193
Country of Publication:
United States
Language:
English