Chitin synthetase in encysting Giardia lamblia and Entamoeba invadens
Giardia lamblia (Gl) and Entamoeba invadens (Ei) are protozoan parasites with two morphologic stages in their life cycles. Motile trophozoites colonize the intestine of humans and reptiles respectively. Water resistant cysts, which can survive outside the host, transmit infection. In vitro cyst formation of Ei from trophozoites has been reported, and the authors have recently induced in vitro encystation of Gl. Although the cyst walls of both parasites contain chitin, it synthesis by encysting trophozoites has not been reported. The authors now show that encystation conditions greatly increase chitin synthetase (CS) specific activity (incorporation of /sup 3/H GlcNAc from UDP-GlcNAc into TCA-or alcohol-precipitable material). Extracts of encysting Gl incorporated 3.6 nmol/mg protein in 5 hr compared to < 0.005 in controls. Extracts of encysting Fi incorporated 4.8 n mol/mg protein, compared to 1.7 in the control. CS activity of both parasites requires preformed chitin. The Gl enzyme requires a reducing agent, is inhibited by digitonin and the CS inhibitors, polyoxin D and Nikkomycin, but not by tunicamycin. The product is digested by chitinase. Ei enzyme does not require a reducing agent and is stimulated by 1 mg/ml digitonin, but inhibited by higher concentrations. These studies demonstrate CS enzymes which may play important roles in encystation of Gl and Ei.
- Research Organization:
- Univ. of California, San Diego
- OSTI ID:
- 6179847
- Report Number(s):
- CONF-870644-; TRN: 87-034015
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 46:6; Conference: 78. annual meeting of the American Society of Biological Chemists conference, Philadelphia, PA, USA, 7 Jun 1987
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CHITIN
BIOSYNTHESIS
LIGASES
BIOLOGICAL FUNCTIONS
ENZYME ACTIVITY
PARASITES
LIFE CYCLE
CELL WALL
PROTOZOA
RESPONSE MODIFYING FACTORS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
AMINES
ANIMALS
CARBOHYDRATES
CELL CONSTITUENTS
ENZYMES
FUNCTIONS
INVERTEBRATES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MICROORGANISMS
MUCOPOLYSACCHARIDES
ORGANIC COMPOUNDS
POLYSACCHARIDES
SACCHARIDES
SYNTHESIS
550201* - Biochemistry- Tracer Techniques