Secretion of a novel developmentally regulated chitinase (family 19 glycosyl hydrolase) into the perivitelline fluid of the parasitic nematode, Ascaris suum

Mol Biochem Parasitol. Sep-Oct 2002;124(1-2):11-21. doi: 10.1016/s0166-6851(02)00155-x.

Abstract

The early development of the parasitic nematode, Ascaris suum, occurs within a chitinous eggshell and an abundant chitinase (As-p50) has been identified in the perivitelline fluid (PVF) surrounding the infective larva prior to hatching. A cDNA encoding As-p50 was cloned, sequenced and the protein expressed in Escherichia coli. As-p50 is a member of glycosyl hydrolase family 19, previously identified only in plants, making the characterization of As-p50 the first family 19 glycosyl hydrolase from any animal species. As expected, the chitinase activity of recombinant As-p50 or isolated PVF was insensitive to allosamidin. As-p50 expression was developmentally regulated. As-p50 mRNA appeared between days 5 and 8 of development prior to the formation of the first-stage larva (L1). The As-p50 protein and chitinase activity appeared later between days 8 and 15 and remained at constant levels until hatching. GFP-promoter constructs of C08B6.4, the most closely related Caenorhabditis elegans As-p50 homologue, were expressed in hypodermal cells of 3-fold stage larvae and L1s with a timing similar to that of As-p50 and the fusion protein was secreted into the space between the hypodermis and the cuticle. Taken together, these results suggest that As-p50 is involved in the formation of the L1 cuticle and/or the initial molt; however, As-p50 may be multifunctional and also responsible for the digestion of the eggshell during hatching.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Ascaris suum / enzymology*
  • Ascaris suum / genetics
  • Ascaris suum / growth & development
  • Caenorhabditis elegans / enzymology
  • Caenorhabditis elegans / genetics
  • Chitinases / chemistry
  • Chitinases / genetics
  • Chitinases / metabolism*
  • Cloning, Molecular
  • Gene Expression Regulation, Developmental*
  • Helminth Proteins / chemistry
  • Helminth Proteins / genetics
  • Helminth Proteins / metabolism*
  • Molecular Sequence Data
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Sequence Analysis, DNA
  • Vitelline Membrane / metabolism*

Substances

  • Helminth Proteins
  • Recombinant Proteins
  • As-p50 protein, Ascaris suum
  • Chitinases