title: Shedding light on the expansion and diversification of the Cdc48 protein family during the rise of the eukaryotic cell.
abstract: A defining feature of eukaryotic cells is the presence of various distinct membrane-bound compartments with different metabolic roles. Material exchange between most compartments occurs via a sophisticated vesicle trafficking system. This intricate cellular architecture of eukaryotes appears to have emerged suddenly, about 2 billion years ago, from much less complex ancestors. How the eukaryotic cell acquired its internal complexity is poorly understood, partly because no prokaryotic precursors have been found for many key factors involved in compartmentalization. One exception is the Cdc48 protein family, which consists of several distinct classical ATPases associated with various cellular activities (AAA+) proteins with two consecutive AAA domains.
  
  
  
  Here, we have classified the Cdc48 family through iterative use of hidden Markov models and tree building. We found only one type, Cdc48, in prokaryotes, although a set of eight diverged members that function at distinct subcellular compartments were retrieved from eukaryotes and were probably present in the last eukaryotic common ancestor (LECA). Pronounced changes in sequence and domain structure during the radiation into the LECA set are delineated. Moreover, our analysis brings to light lineage-specific losses and duplications that often reflect important biological changes. Remarkably, we also found evidence for internal duplications within the LECA set that probably occurred during the rise of the eukaryotic cell.
  
  
  
  Our analysis corroborates the idea that the diversification of the Cdc48 family is closely intertwined with the development of the compartments of the eukaryotic cell.
authors.affiliation: Département des neurosciences fondamentales, Université de Lausanne, Rue du Bugnon 9, CH-1005, Lausanne, Switzerland.
authors.forename: Nickias
authors.initials: N
authors.lastname: Kienle
authors.affiliation: Sir William Dunn School of Pathology, Research Group Cell Biology of Intercellular Signaling, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK.
authors.forename: Tobias H
authors.initials: TH
authors.lastname: Kloepper
authors.affiliation: Département des neurosciences fondamentales, Université de Lausanne, Rue du Bugnon 9, CH-1005, Lausanne, Switzerland. Dirk.Fasshauer@unil.ch.
authors.forename: Dirk
authors.identifier: 0000-0002-1040-4282
authors.initials: D
authors.lastname: Fasshauer
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics; D005075:Biological Evolution; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000235:genetics; D005057:Eukaryotic Cells / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D019143:Evolution, Molecular; D008390:Markov Chains; D010802:Phylogeny; D011387:Prokaryotic Cells / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D000072417:Protein Domains; D000074405:Valosin Containing Protein
chemical_list: D018797:Cell Cycle Proteins; D000251:Adenosine Triphosphatases; D000074405:Valosin Containing Protein
keywords: AAA+ proteins; Compartmentalization; Eukaryogenesis; LECA; NSF; Organelles; SELMA; Vesicle trafficking