Adenosine 3', 5'-cyclic monophosphate levels in Thermomonospora curvata during cellulase biosynthesis
The enzymatic degradation of cellulose requires the synergistic activity of at least three enzymes: exo-beta-1,4-glucanase (EC3.2.1.91), endo-beta-1,4-glucanase (EC3.2.1.4), and beta-glucosidase (EC3.2.1.21). Despite extensive studies on a variety of cellulolytic bacteria and fungi, the mechanism(s) regulating the biosynthesis of this inducible catabolic enzyme complex remains unknown. The intracellular concentrations of cyclic nucleotides such as adenosine 3',5'-cyclic monophosphate (cAMP) have been shown to play a major role in mediating catabolite repression of enzyme biosynthesis. The cAMP acts through a cAMP receptor protein (termed CRP or CAP) which is a dimer having two identical subunits each capable of binding one molecule of cAMP. The N-terminal domain of the CRP binds the cAMP while the C-terminal domain binds to DNA at the promotor region of a cAMP-dependent operon and stimulates transcription by promoting the formation of a preinitiation complex between RNA polymerase and the DNA. Intracellular cAMP levels in E. coli (the prototype organism for such studies) are influenced by the type and availability of carbon source used for growth. High intracellular cAMP levels should lead to higher concentrations of cAMP-CRP complexes which should increase the transcription rates for cAMP-dependent operons (such as the lac operon of beta-galactosidase) and indeed the differential rate of beta-galactosidase biosynthesis correlates to intracellular cAMP levels. In the case of cellulase, catabolite repression by glucose or other readily metabolizable compounds closely controls production in an apparently similar manner and therefore a correlation may exist between enzyme biosynthesis and intracellular cAMP levels. This communication describes the fluctuation in cAMP levels during cellulase induction and repression in the thermophilic actinomycete, Thermomonospora curvata.
- Research Organization:
- Dept. of Microbiology, Clemson Univ., Clemson, SC 29631, USA
- OSTI ID:
- 5229313
- Journal Information:
- Biotechnol. Bioeng.; (United States), Journal Name: Biotechnol. Bioeng.; (United States) Vol. 25:9; ISSN BIBIA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Preferential utilization of cellobiose by Thermomonospora curvata
Effect of catabolite repression on the mer operon
Related Subjects
140504* -- Solar Energy Conversion-- Biomass Production & Conversion-- (-1989)
550700 -- Microbiology
59 BASIC BIOLOGICAL SCIENCES
ACTINOMYCES
AMP
BACTERIA
BIOCHEMICAL REACTION KINETICS
BIOSYNTHESIS
CELLULASE
ENZYMES
GLYCOSYL HYDROLASES
HYDROLASES
KINETICS
MICROORGANISMS
NUCLEOTIDES
O-GLYCOSYL HYDROLASES
ORGANIC COMPOUNDS
REACTION KINETICS
SYNTHESIS