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Effects of tunicamycin on protein glycosylation and development inVolvox carteri
1Department of Biophysics, The Weizmann Institute of Science, Rehovot, Israel.
Abstract:
The involvement of protein glycosylation in regulation of the development of the multicellular green alga,Volvox carteri, was studied using the antibiotic, tunicamycin. Three specific developmental processes were found to be affected by the antibiotic: reproductive cell maturation; establishment of polar cellular organization during embryogenesis and release of progeny spheroids from the parental spheroids. Tunicamycin inhibited the transfer of GlcNAc-1-phosphate to dolichyl phosphate which is catalyzed byVolvox membrane preparations. Changes in the glycosylation of several secreted and cellular glycoproteins were observed when proteins were labelled with radioactive amino acids and sugars in the absence and presence of tunicamycin and then electrophoresed on sodium dodecylsulfate-polyacrylamide slab gels. The levels of a few secreted proteins were reduced in tunicamycin treated cultures and one protein band appeared exclusively in the treated cells. Tunicamycin treatment also altered the electrophoretic mobility of radio-iodinated surface macromolecules. Binding of concanavalin A by tunicamycin treatedVolvox spheroids was drastically reduced. It is there-fore likely that the aberrant development results from inhibition of protein glycosylation and the consequent changes in the structure of the cellular, secreted and surface glycoproteins.
Insights
Protein glycosylation is crucial for Volvox carteri development. Inhibiting this process with tunicamycin disrupts reproductive cell maturation, cellular organization, and progeny release, highlighting its regulatory role.
Area of Science:
- * Molecular Biology
- * Developmental Biology
- * Biochemistry
Background:
- * Protein glycosylation plays a vital role in cellular processes across eukaryotes.
- * The multicellular green alga Volvox carteri exhibits complex developmental patterns.
- * Understanding glycosylation's impact on Volvox development can provide insights into conserved biological mechanisms.
Purpose of the Study:
- * To investigate the role of protein glycosylation in regulating Volvox carteri development.
- * To identify specific developmental processes affected by the inhibition of glycosylation.
- * To elucidate the molecular changes associated with disrupted glycosylation in Volvox.
Main Methods:
- * Treatment of Volvox carteri with the antibiotic tunicamycin, an inhibitor of protein glycosylation.
- * Biochemical assays to assess tunicamycin's effect on key glycosylation enzymes.
- * Metabolic labeling of proteins with radioactive amino acids and sugars.
- * Electrophoresis (SDS-PAGE) to analyze changes in glycoprotein structure and levels.
- * Lectin binding assays (Concanavalin A) to evaluate surface glycoprotein alterations.
Main Results:
- * Tunicamycin treatment significantly affected reproductive cell maturation, embryogenesis, and progeny release in Volvox.
- * The antibiotic inhibited the enzymatic transfer of GlcNAc-1-phosphate to dolichyl phosphate.
- * Alterations in the glycosylation patterns of cellular and secreted glycoproteins were observed.
- * Tunicamycin treatment led to reduced levels of some secreted proteins and the appearance of a novel protein band.
- * Changes in the electrophoretic mobility of surface macromolecules and reduced Concanavalin A binding were noted.
Conclusions:
- * Inhibition of protein glycosylation by tunicamycin leads to aberrant development in Volvox carteri.
- * The observed developmental defects are likely due to alterations in the structure of cellular, secreted, and surface glycoproteins.
- * Protein glycosylation is a critical regulatory mechanism for key developmental processes in Volvox.
