title: Primary structure and expression of a gamete lytic enzyme in Chlamydomonas reinhardtii: similarity of functional domains to matrix metalloproteases.
abstract: A gamete lytic enzyme (GLE) of Chlamydomonas reinhardtii is a zinc metalloprotease and mediates digestion of the cell walls of the two mating-type gametes during mating as a necessary prelude to cell fusion. The nucleotide sequence analysis of a cDNA revealed that GLE is synthesized in a preproenzyme form, a 638-amino acid polypeptide (Mr, 69,824) with a 28-amino acid signal peptide, a 155-amino acid propolypeptide, and a 455-amino acid mature polypeptide (Mr, 49,633). A potential site for autocatalytic activation was contained within the propolypeptide and a zinc binding site found within the mature polypeptide; both sites were highly homologous to those in mammalian collagenase. A putative calcium binding site was present in the near C-terminal region of the mature GLE. Both propolypeptide and mature polypeptide had potential sites for asparagine-linked glycosylation, and the Arg-(Pro)3 and Arg-(Pro)2 motifs, which are known to exist in hydroxyproline-rich glycoproteins of the Chlamydomonas cell wall. Northern blot analysis revealed that steady-state levels of the 2.4-kilobase GLE mRNA increased during growth and mitotic cell division in the vegetative cell cycle and also increased markedly during gametogenesis under nitrogen-starved conditions.
authors.affiliation: Department of Biology, Faculty of Science, Kobe University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kinoshita
authors.forename: H
authors.initials: H
authors.lastname: Fukuzawa
authors.forename: T
authors.initials: T
authors.lastname: Shimada
authors.forename: T
authors.initials: T
authors.lastname: Saito
authors.forename: Y
authors.initials: Y
authors.lastname: Matsuda
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016825:Chlamydomonas reinhardtii / Q000201:enzymology / Q000235:genetics* / Q000502:physiology; D004792:Enzyme Precursors / Q000235:genetics; D006801:Humans; D008666:Metalloendopeptidases / Q000235:genetics*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid
chemical_list: D004792:Enzyme Precursors; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D008666:Metalloendopeptidases; C074529:gamete lytic enzyme, Chlamydomonas