Transcriptional regulation of beta-glucanase activity in the ruminal bacterium, Prevotella bryantii B14.
The ruminal bacterium, Prevotella bryantii B(1)4, grew more rapidly with glucose as an energy source than mannose (0.73 versus 0.47 h(-1)) and had 8-fold less beta-glucanase activity (50 versus 400 nmol reducing sugar mg protein(-1) min(-1)). Cultures that were provided with glucose and mannose had little beta-glucanase activity even though both sugars were utilized simultaneously. The observation that glucose and mannose were utilized simultaneously indicated that beta-glucanase expression was not merely a simple induction or inducer exclusion. When glucose was added to cultures growing on mannose, hexose flux through the glucomannokinase increased 1.5-fold, and this increase was associated with an almost immediate decrease in beta-glucanase mRNA. After only three generation (doubling) times, the amount of beta-glucanase mRNA was comparable to that observed in cells growing only with glucose. These results indicate that beta-glucanase activity is transcriptionally regulated. However, further work will be needed to define more precisely the nature of this regulation and to identify the intermediate in this response.
Fields
Matthew W
MW
Agricultural Research Service, USDA, Cornell University, Ithaca, NY, 14853, USA.
Russell
James B
JB
D015152:Blotting, Northern; D002480:Cellulase / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D005947:Glucose / Q000378:metabolism; D008358:Mannose / Q000378:metabolism; D018720:Prevotella / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D014158:Transcription, Genetic / Q000502:physiology*
D012333:RNA, Messenger; D002480:Cellulase; D005947:Glucose; D008358:Mannose