Structure of the sea urchin hatching enzyme gene.
The sea urchin embryo develops from an encased to a free-living larva by secreting at an early stage the hatching enzyme, a metalloprotease which hydrolyses a protective envelope derived from the egg extracellular matrix. Genomic clones containing the entire hatching enzyme gene were isolated from a lambda phage sea urchin library and the complete sequence of the transcription unit was determined. The hatching enzyme gene spans 6.3 kb and comprises 9 exons. The exon/intron organization of the hatching enzyme gene is similar but not identical to those of the vertebrate collagenases and stromelysins. The position and/or phase of several introns are different even in the N-terminal moiety where similarity between echinoderm and vertebrate enzymes was first detected. The active-center domain is encoded by a 1-1 class exon whose sequence, length and borders are highly conserved and might be considered as coding for a protein module. Adjacent to the active-center exon, the hatching enzyme gene has an additional 1-1 exon which codes for a threonine-rich region. This provides further evidence that the matrix-degrading metalloproteinases evolved by shuffling exons of the 1-1 class. Phylogeny analysis indicates a close relationship between the sea urchin and vertebrate enzymes.
Ghiglione
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Unité de Biologie Cellulaire Marine, Centre National de la Recherche Scientifique, Villefranche-sur-Mer, France.
Lhomond
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Lepage
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Gache
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004625:Embryo, Nonmammalian / Q000201:enzymology*; D005091:Exons; D005796:Genes; D015698:Genomic Library; D006868:Hydrolysis; D008666:Metalloendopeptidases / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D011110:Polymorphism, Genetic; D012617:Sea Urchins / Q000196:embryology / Q000235:genetics*; D014158:Transcription, Genetic; D014714:Vertebrates / Q000235:genetics
D008666:Metalloendopeptidases; C024344:envelysin