ZFIN ID: ZDB-PUB-081125-3
Purification and characterization of zebrafish hatching enzyme - an evolutionary aspect of the mechanism of egg envelope digestion
Sano, K., Inohaya, K., Kawaguchi, M., Yoshizaki, N., Iuchi, I., and Yasumasu, S.
Date: 2008
Source: The FEBS journal   275(23): 5934-5946 (Journal)
Registered Authors: Inohaya, Keiji
Keywords: astacin family, egg envelope, hatching enzyme, molecular evolution
MeSH Terms:
  • Amino Acid Sequence
  • Animals
  • Catalysis
  • Chromatography, High Pressure Liquid
  • Egg Proteins/chemistry
  • Egg Proteins/genetics
  • Egg Proteins/metabolism
  • Electrophoresis, Polyacrylamide Gel
  • Embryo, Nonmammalian/enzymology
  • Embryo, Nonmammalian/metabolism
  • Evolution, Molecular*
  • Gene Expression Regulation, Developmental
  • Gene Expression Regulation, Enzymologic
  • In Situ Hybridization
  • Kinetics
  • Membrane Glycoproteins/chemistry
  • Membrane Glycoproteins/genetics
  • Membrane Glycoproteins/metabolism
  • Metalloendopeptidases/chemistry
  • Metalloendopeptidases/genetics*
  • Metalloendopeptidases/metabolism
  • Molecular Sequence Data
  • Molecular Weight
  • Oryzias/genetics
  • Oryzias/metabolism
  • Receptors, Cell Surface/chemistry
  • Receptors, Cell Surface/genetics
  • Receptors, Cell Surface/metabolism
  • Recombinant Proteins/biosynthesis
  • Recombinant Proteins/chemistry
  • Species Specificity
  • Substrate Specificity
  • Zebrafish/genetics*
  • Zebrafish/metabolism
  • Zona Pellucida/enzymology
  • Zona Pellucida/metabolism*
  • Zygote/enzymology
  • Zygote/metabolism
PubMed: 19021768 Full text @ FEBS J.
There are two hatching enzyme homologues in the zebrafish genome: zebrafish hatching enzyme ZHE1 and ZHE2. Northern blot and RT-PCR analysis revealed that ZHE1 was mainly expressed in pre-hatching embryos, whereas ZHE2 was rarely expressed. This was consistent with the results obtained in an experiment conducted at the protein level, which demonstrated that one kind of hatching enzyme, ZHE1, was able to be purified from the hatching liquid. Therefore, the hatching of zebrafish embryo is performed by a single enzyme, different from the finding that the medaka hatching enzyme is an enzyme system composed of two enzymes, medaka high choriolytic enzyme (MHCE) and medaka low choriolytic enzyme (MLCE), which cooperatively digest the egg envelope. The six ZHE1-cleaving sites were located in the N-terminal regions of egg envelope subunit proteins, ZP2 and ZP3, but not in the internal regions, such as the ZP domains. The digestion manner of ZHE1 appears to be highly analogous to that of MHCE, which partially digests the egg envelope and swells the envelope. The cross-species digestion using enzymes and substrates of zebrafish and medaka revealed that both ZHE1 and MHCE cleaved the same sites of the egg envelope proteins of two species, suggesting that the substrate specificity of ZHE1 is quite similar to that of MHCE. However, MLCE did not show such similarity. Because HCE and LCE are the result of gene duplication in the evolutionary pathway of Teleostei, the present study suggests that ZHE1 and MHCE maintain the character of an ancestral hatching enzyme, and that MLCE acquires a new function, such as promoting the complete digestion of the egg envelope swollen by MHCE.