Biochemical Analysis of Caenorhabditis elegans Surface Mutants

A collection of Caenorhabditis elegans mutants that show ectopic surface lectin binding (Srf mutants) was analyzed to determine the biochemical basis for this phenotype. This analysis involved selective removal or labeling of surface components, specific labeling of surface glycans, and fractionation of total protein with subsequent detection of wheat germ agglutinin (WGA) binding proteins. Wild-type and mutant nematodes showed no differences in their profiles of extractable surface glycoproteins or total WGA-binding proteins, suggesting that the ectopic lectin binding does not result from the novel expression of surface glycans. Instead, these results support a model in which ectopic lectin binding results from an unmasking of glycosylated components present in the insoluble cuticle matrix of wild-type animals. To explain the multiple internal defects found in some surface mutants, we propose that these mutants have a basic defect in protein processing. This defect would interfere with the expression of the postulated masking protein(s), as well as other proteins required for normal development.