title: The NOMEGA gene required for female gametophyte development encodes the putative APC6/CDC16 component of the Anaphase Promoting Complex in Arabidopsis.
abstract: Development of the female gametophyte involves several rounds of nuclear divisions during which nuclei are rearranged and finally cellularized to form a mature seven-celled embryo sac. During these nuclear divisions, key proteins involved in the cell cycle need to be degraded quickly in order to facilitate both the metaphase-anaphase transition stage and late anaphase. Here, we report the characterization of an Arabidopsis mutant nomega, which results in arrest of the embryo sac development at the two-nucleate stage. The NOMEGA gene product shows high homology to the APC6/cell division cycle (CDC)16 subunit of the Anaphase Promoting Complex/Cyclosome (APC/C). The phenotype of the nomega mutant is quite different from that of the hobbit mutant, which had suggested a role for the plant APC/C in auxin signalling. We show that nomega mutant embryo sacs are unable to degrade Cyclin B, an important APC/C substrate, providing further evidence of a role for the NOMEGA gene product and the plant APC/C in cell cycle progression during gametophyte development.
authors.affiliation: Institute of Molecular and Cell Biology, 1 Research Link, National University of Singapore, Singapore 117604, Singapore.
authors.forename: Hong-Sien
authors.initials: HS
authors.lastname: Kwee
authors.forename: Venkatesan
authors.initials: V
authors.lastname: Sundaresan
mesh_terms: D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D064194:Apc6 Subunit, Anaphase-Promoting Complex-Cyclosome; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D018525:Germination / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010641:Phenotype; D021122:Protein Subunits / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics / Q000378:metabolism*
chemical_list: C577381:Anaphase-promoting complex subunit 6 protein, Arabidopsis; D064194:Apc6 Subunit, Anaphase-Promoting Complex-Cyclosome; D029681:Arabidopsis Proteins; D021122:Protein Subunits; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome