Macromolecular organization of the cellulolytic enzyme complex of Clostridium thermocellum as revealed by electron microscopy
Clostridium thermocellum JW20 and YM4 both synthesize cellulolytic enzyme complexes, cellulosomes, when grown on medium containing cellulose. In the early stages of cultivation, the cellulosomes from both species exist as tightly packed complexes (tight cellulosomes). These subsequently decompose to loosely packed complexes (loose cellulosomes) and ultimately to free polypeptides. Examination of the loose cellulosomal particles showed that the contain rows of equidistantly spaced, similarly sized polypeptide subunits, with an apparently identical orientation arranged parallel to the major axis of the cellulosome. It is postulated that on binding of a cellulose chain alongside such a row of subunits a simultaneous multicutting event occurs that leads to the release of cellooligosaccharides of four cellobiose units in length (C/sub 4/). Rows of smaller-sized subunits with lower center-to-center distances, which are also present in the cellulosome, subsequently cleave the C/sub 4/ fragments (or cellulose) to C/sub 2/ (cellotetraose) or C/sub 1/ (cellobiose). In this way the cellulosome can catalyze the complete hydrolysis of cellulose.
- Research Organization:
- Univ. of Goettingen, West Germany
- DOE Contract Number:
- AS09-79ER10499
- OSTI ID:
- 5429227
- Journal Information:
- Appl. Environ. Microbiol.; (United States), Vol. 53:12
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
CELLULOSE
ENZYMATIC HYDROLYSIS
CLOSTRIDIUM THERMOCELLUM
CELLULOLYTIC ACTIVITY
CELL CONSTITUENTS
ELECTRON MICROSCOPY
ENZYME ACTIVITY
BACTERIA
CARBOHYDRATES
CHEMICAL REACTIONS
CLOSTRIDIUM
DECOMPOSITION
HYDROLYSIS
LYSIS
MICROORGANISMS
MICROSCOPY
ORGANIC COMPOUNDS
POLYSACCHARIDES
SACCHARIDES
SOLVOLYSIS
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