The Chlamydomonas hatching enzyme, sporangin, is expressed in specific phases of the cell cycle and is localized to the flagella of daughter cells within the sporangial cell wall.
The timely breakdown of the extracellular matrix by proteolytic enzymes is essential for development, morphogenesis and cell proliferation in plant and animal cells. Sporangin of the unicellular green alga Chlamydomonas reinhardtii that mediates breakdown of the sporangial cell wall to liberate the daughter cells after cell division is characterized as a subtilase-like serine protease. The sporangin gene is specifically transcribed during S/M phase in a synchronized vegetative cell cycle. In immunoblot analyses using a polyclonal antibody raised against the sporangin polypeptide, the enzyme is synthesized after mitotic cell division and accumulated in the daughter cells before hatching. Immunofluorescence analyses showed that sporangin is localized to the flagella of the daughter cells within the sporangial cell wall, and released into the culture medium. The data suggest that sporangin is released from flagella concurrently with the digestion of sporangial cell wall, and then the daughter cells are hatched from the sporangia in the Chlamydomonas vegetative cell cycle.
Kubo
Takeaki
T
Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan. kubot@lif.kyoto-u.ac.jp
Kaida
Shinsuke
S
Abe
Jun
J
Saito
Tatsuaki
T
Fukuzawa
Hideya
H
Matsuda
Yoshihiro
Y
D020418:Algal Proteins / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002453:Cell Cycle; D002473:Cell Wall / Q000201:enzymology* / Q000235:genetics; D016825:Chlamydomonas reinhardtii / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D005407:Flagella / Q000201:enzymology* / Q000235:genetics; D020869:Gene Expression Profiling; D008969:Molecular Sequence Data; D012697:Serine Endopeptidases / Q000235:genetics* / Q000378:metabolism
D020418:Algal Proteins; D018076:DNA, Complementary; D012697:Serine Endopeptidases