title: Glycogen biosynthesis via UDP-glucose in the ruminal bacterium Prevotella bryantii B1(4).
abstract: Prevotella bryantii is an important amylolytic bacterium in the rumen that produces considerable amounts of glycogen when it is grown on maltose. Radiolabel studies indicated that glucose-1-phosphate was converted to UDP-glucose, and this latter intermediate served as the immediate precursor for glycogen synthesis. High levels of UDP-glucose pyrophosphorylase activities (> 1,492 nmol/min/mg of protein) were detected in cells grown on maltose, cellobiose, glucose, or sucrose, and activity was greatly stimulated (by approximately 60-fold) by the addition of fructose-1,6-bis phosphate (half-maximal activation concentration was 240 microM). However, ADP-glucose pyrophosphorylase activity was not detected in any of the cultures. Glycogen synthase activity in maltose-grown cultures (48 nmol/min/mg of protein) was higher than that in cellobiose-, sucrose-, and glucose-grown cultures (< 26 nmol/min/mg of protein). This is the first report of a bacterium that exclusively uses UDP-glucose to synthesize glycogen. The elucidation of this unique glycogen biosynthesis pathway provides information necessary to further investigate the role of bacterial glycogen accumulation in rumen metabolism.
authors.affiliation: Department of Animal Sciences, University of Kentucky, Lexington 40546-0215, USA.
authors.forename: J
authors.initials: J
authors.lastname: Lou
authors.forename: K A
authors.initials: KA
authors.lastname: Dawson
authors.forename: H J
authors.initials: HJ
authors.lastname: Strobel
mesh_terms: D000494:Allosteric Regulation; D000818:Animals; D006003:Glycogen / Q000096:biosynthesis*; D018720:Prevotella / Q000378:metabolism*; D012417:Rumen / Q000382:microbiology*; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase / Q000378:metabolism; D014532:Uridine Diphosphate Glucose / Q000378:metabolism*
chemical_list: D006003:Glycogen; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase; D014532:Uridine Diphosphate Glucose