title: Genomic evolution and complexity of the Anaphase-promoting Complex (APC) in land plants.
abstract: BACKGROUND
  The 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.
  
  
  RESULTS
  Here, 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.
  
  
  CONCLUSIONS
  The 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.
authors.affiliation: Laboratório de Biologia Molecular de Plantas, Instituto de Bioquímica Médica, CCS, Cidade Universitária - Ilha do Fundão, CEP 21941-590 Rio de Janeiro, Brasil. paulof@bioqmed.ufrj.br
authors.forename: Marcelo de F
authors.initials: Mde F
authors.lastname: Lima
authors.forename: Núbia B
authors.initials: NB
authors.lastname: Eloy
authors.forename: Camila
authors.initials: C
authors.lastname: Pegoraro
authors.forename: Rauan
authors.initials: R
authors.lastname: Sagit
authors.forename: Cristian
authors.initials: C
authors.lastname: Rojas
authors.forename: Thiago
authors.initials: T
authors.lastname: Bretz
authors.forename: Lívia
authors.initials: L
authors.lastname: Vargas
authors.forename: Arne
authors.initials: A
authors.lastname: Elofsson
authors.forename: Antonio Costa
authors.initials: AC
authors.lastname: de Oliveira
authors.forename: Adriana S
authors.initials: AS
authors.lastname: Hemerly
authors.forename: Paulo Cg
authors.initials: PC
authors.lastname: Ferreira
mesh_terms: D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D017360:Arabidopsis / Q000235:genetics; D001483:Base Sequence; D000460:Chlorophyta / Q000201:enzymology / Q000235:genetics; D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics; D019143:Evolution, Molecular; D018506:Gene Expression Regulation, Plant; D014644:Genetic Variation; D018745:Genome, Plant / Q000235:genetics; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics; D010802:Phylogeny; D010940:Plant Proteins / Q000145:classification / Q000235:genetics*; D010944:Plants / Q000201:enzymology / Q000235:genetics*; D032107:Populus / Q000235:genetics; D021122:Protein Subunits / Q000145:classification / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000461:Rhodophyta / Q000201:enzymology / Q000235:genetics; D013045:Species Specificity; D026801:Synteny; D043743:Ubiquitin-Protein Ligase Complexes / Q000145:classification / Q000235:genetics*
chemical_list: D010940:Plant Proteins; D021122:Protein Subunits; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome