Genomic evolution and complexity of the Anaphase-promoting Complex (APC) in land plants

Abstract

BackgroundThe orderly progression through mitosis is regulated by the Anaphase-Promoting Complex (APC), a large multiprotein E3 ubiquitin ligase that targets key cell-cycle regulators for destruction by the 26 S proteasome. The APC is composed of at least 11 subunits and associates with additional regulatory activators during mitosis and interphase cycles. Despite extensive research on APC and activator functions in the cell cycle, only a few components have been functionally characterized in plants.ResultsHere, we describe an in-depth search for APC subunits and activator genes in the Arabidopsis, rice and poplar genomes. Also, searches in other genomes that are not completely sequenced were performed. Phylogenetic analyses indicate that some APC subunits and activator genes have experienced gene duplication events in plants, in contrast to animals. Expression patterns of paralog subunits and activators in rice could indicate that this duplication, rather than complete redundancy, could reflect initial specialization steps. The absence of subunit APC7 from the genome of some green algae species and as well as from early metazoan lineages, could mean that APC7 is not required for APC function in unicellular organisms and it may be a result of duplication of another tetratricopeptide (TPR) subunit. Analyses of TPR evolution suggest that duplications of subunits started from the central domains.ConclusionsThe increased complexity of the APC gene structure, tied to the diversification of expression paths, suggests that land plants developed sophisticated mechanisms of APC regulation to cope with the sedentary life style and its associated environmental exposures.

The Anaphase-Promoting Complex Is a Dual Integrator That Regulates Both MicroRNA-Mediated Transcriptional Regulation ofCyclin B1and Degradation of Cyclin B1 duringArabidopsisMale Gametophyte Development

“…For example, APC6 and APC8 both have a TPR domain, while APC2 does not; mutants of APC6 and APC8 both showed defects in male transmission (Kwee and Sundaresan, 2003; Table 1), but the apc2 mutant did not (Capron et al, 2003b). These results indicate that while the overall structure of the APC/C is conserved among eukaryotes, this E3 ligase might have assumed specialized functions in different kingdoms (Lima et al, 2010). Another important layer of APC/C regulation in plants could be through subunit availability in specific tissues and/or cellular compartment, as it is known that APC subunits are differentially expressed in Arabidopsis organs (Eloy et al, 2006).…”

“…The APC/C in Arabidopsis contains at least 11 subunits (Capron et al, 2003a). Among them, APC3, APC5, APC6, APC7, and APC8 each contain a tetratricopeptide repeat (TPR) protein-protein interaction domain and are expected to function as receptors that interact with regulatory proteins (Lima et al, 2010). Without APC/C, cells cannot separate their sister chromatids in anaphase, cannot exit from mitosis to divide into two daughter cells, and cannot initiate the steps necessary for DNA replication in S phase (Peters, 2006).…”

Known and novel post-transcriptional regulatory sequences are conserved across plant families

“…3B-D) begs the question of whether CPuORFs are, in fact, regulatory elements or, alternatively, whether their associated mRNAs should be considered bicistronic transcripts. Strikingly, CPuORF-24n is identical to GenBank accession CDC26, a small subunit of the anaphase promoting complex (APC) (Dong et al 2007;de F Lima et al 2010). CPuORF-24n/CDC26 appears as a distinct transcript in metazoans and fungi, but in plants it is consistently found as a uORF upstream of a mORF that is annotated as adenylate cyclase.…”

Development and Organization of Cell Types and Tissues

“…This depends on the ubiquitin ligase (E3) activity of the anaphasepromoting complex/ cyclosome (APC/C) (Peters 2006 ). The APC/C in Arabidopsis contains at least 11 subunits (Capron et al 2003a , b ;Lima et al 2010 ). Without APC/C, cells cannot separate their sister chromatids during anaphase, cannot exit from mitosis, and to divide into two daughter cells, and cannot do DNA replication in S phase.…”