Primary structure and expression of a gamete lytic enzyme in Chlamydomonas reinhardtii: similarity of functional domains to matrix metalloproteases.
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.
Kinoshita
T
T
Department of Biology, Faculty of Science, Kobe University, Japan.
Fukuzawa
H
H
Shimada
T
T
Saito
T
T
Matsuda
Y
Y
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
D004792:Enzyme Precursors; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D008666:Metalloendopeptidases; C074529:gamete lytic enzyme, Chlamydomonas