Journal of Molecular Evolution

, Volume 63, Issue 4, pp 504–512

Proteasome-Related HslU and HslV Genes Typical of Eubacteria Are Widespread in Eukaryotes


DOI: 10.1007/s00239-005-0282-1

Cite this article as:
Ruiz-González, M.X. & Marín, I. J Mol Evol (2006) 63: 504. doi:10.1007/s00239-005-0282-1


Many eubacteria contain an ATP-dependent protease complex, which is built by multiple copies of the HslV and HslU proteins and is therefore called HslVU. HslU proteins are AAA + ATPases, while HslV proteins are proteases that show highly significant similarity to β subunits of proteasomes. Therefore, the HslVU complex has been envisaged as a precursor or ancestral type of proteasome. Here we show that species of most of the main eukaryotic lineages have HslU and HslV genes very similar to those found in proteobacteria. We have detected them in amoebozoa, plantae, chromoalveolata, rhizaria, and excavata species. Phylogenetic analyses suggest that these genes have been obtained by endosymbiosis from the proteobacterial ancestor that gave rise to eukaryotic mitochondria. The products encoded by these eukaryotic genes adopt, according to modeling based on the known crystal structures of prokaryotic HslU and HslV proteins, conformations that are compatible with their being fully active, suggesting that functional HslVU complexes may be present in many eukaryotic species.


HslVU complexProteasomeProtein quality controlEarly evolutionEndosymbiosisComparative genomics

Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  1. 1.Departamento de GenéticaUniversidad de ValenciaValenciaSpain
  2. 2.Department of ZoologySchool of Natural Sciences, University of Dublin Trinity CollegeIreland