title: Horizontal transfer of β-carbonic anhydrase genes from prokaryotes to protozoans, insects, and nematodes.
abstract: BACKGROUND
  Horizontal gene transfer (HGT) is a movement of genetic information occurring outside of normal mating activities. It is especially common between prokaryotic endosymbionts and their protozoan, insect, and nematode hosts. Although beta carbonic anhydrase (β-CA) plays a crucial role in metabolic functions of many living organisms, the origin of β-CA genes in eukaryotic species remains unclear.
  
  
  METHODS
  This study was conducted using phylogenetics, prediction of subcellular localization, and identification of β-CA, transposase, integrase, and resolvase genes on the MGEs of bacteria. We also structurally analyzed β-CAs from protozoans, insects, and nematodes and their putative prokaryotic common ancestors, by homology modelling.
  
  
  RESULTS
  Our investigations of a number of target genomes revealed that genes coding for transposase, integrase, resolvase, and conjugation complex proteins have been integrated with β-CA gene sequences on mobile genetic elements (MGEs) which have facilitated the mobility of β-CA genes from bacteria to protozoan, insect, and nematode species. The prokaryotic origin of protozoan, insect, and nematode β-CA enzymes is supported by phylogenetic analyses, prediction of subcellular localization, and homology modelling.
  
  
  CONCLUSIONS
  MGEs form a complete set of enzymatic tools, which are relevant to HGT of β-CA gene sequences from prokaryotes to protozoans, insects, and nematodes.
authors.affiliation: School of Medicine, University of Tampere, Medisiinarinkatu 3, FI-33520, Tampere, Finland. zolfaghari.emameh.reza.x@student.uta.fi.|BioMediTech, University of Tampere, FI-33520, Tampere, Finland. zolfaghari.emameh.reza.x@student.uta.fi.|Fimlab Laboratories Ltd and Tampere University Hospital, FI-33520, Tampere, Finland. zolfaghari.emameh.reza.x@student.uta.fi.
authors.forename: Reza
authors.initials: R
authors.lastname: Zolfaghari Emameh
authors.affiliation: School of Medicine, University of Tampere, Medisiinarinkatu 3, FI-33520, Tampere, Finland.
authors.forename: Harlan R
authors.initials: HR
authors.lastname: Barker
authors.affiliation: Department of Information Technology, University of Turku, FI-20520, Turku, Finland.
authors.forename: Martti E E
authors.initials: ME
authors.lastname: Tolvanen
authors.affiliation: School of Medicine, University of Tampere, Medisiinarinkatu 3, FI-33520, Tampere, Finland.|Fimlab Laboratories Ltd and Tampere University Hospital, FI-33520, Tampere, Finland.
authors.forename: Seppo
authors.initials: S
authors.lastname: Parkkila
authors.affiliation: BioMediTech, University of Tampere, FI-33520, Tampere, Finland.|Fimlab Laboratories Ltd and Tampere University Hospital, FI-33520, Tampere, Finland.
authors.forename: Vesa P
authors.initials: VP
authors.lastname: Hytönen
mesh_terms: D000818:Animals; D001419:Bacteria / Q000201:enzymology*; D002256:Carbonic Anhydrases / Q000737:chemistry / Q000235:genetics*; D056890:Eukaryota / Q000201:enzymology*; D022761:Gene Transfer, Horizontal; D020071:Interspersed Repetitive Sequences; D008958:Models, Molecular; D017385:Sequence Homology
chemical_list: D002256:Carbonic Anhydrases
keywords: Beta carbonic anhydrase; Endosymbionts; Evolution; Horizontal gene transfer; Integrase; Mobile genetic elements; Parasite; Plasmid; Resolvase; Transposase