Journal of Molecular Evolution

, 68:256

Comparative Genomics of Phylogenetically Diverse Unicellular Eukaryotes Provide New Insights into the Genetic Basis for the Evolution of the Programmed Cell Death Machinery


DOI: 10.1007/s00239-009-9201-1

Cite this article as:
Nedelcu, A.M. J Mol Evol (2009) 68: 256. doi:10.1007/s00239-009-9201-1


Programmed cell death (PCD) represents a significant component of normal growth and development in multicellular organisms. Recently, PCD-like processes have been reported in single-celled eukaryotes, implying that some components of the PCD machinery existed early in eukaryotic evolution. This study provides a comparative analysis of PCD-related sequences across more than 50 unicellular genera from four eukaryotic supergroups: Unikonts, Excavata, Chromalveolata, and Plantae. A complex set of PCD-related sequences that correspond to domains or proteins associated with all main functional classes—from ligands and receptors to executors of PCD—was found in many unicellular lineages. Several PCD domains and proteins previously thought to be restricted to animals or land plants are also present in unicellular species. Noteworthy, the yeast, Saccharomyces cerevisiae—used as an experimental model system for PCD research, has a rather reduced set of PCD-related sequences relative to other unicellular species. The phylogenetic distribution of the PCD-related sequences identified in unicellular lineages suggests that the genetic basis for the evolution of the complex PCD machinery present in extant multicellular lineages has been established early in the evolution of eukaryotes. The shaping of the PCD machinery in multicellular lineages involved the duplication, co-option, recruitment, and shuffling of domains already present in their unicellular ancestors.


Unicellular eukaryotesApoptosisProgrammed cell deathMetacaspaseDomain shufflingDomain recruitmentLateral gene transfer

Supplementary material

239_2009_9201_MOESM1_ESM.pdf (72 kb)
Supplementary material 1 (PDF 72 kb)
239_2009_9201_MOESM2_ESM.pdf (149 kb)
Supplementary material 2 (PDF 149 kb)

Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.Department of BiologyUniversity of New BrunswickFrederictonCanada