title: Lawsonia intracellularis contains a gene encoding a functional rickettsia-like ATP/ADP translocase for host exploitation.
abstract: ATP/ADP translocases are a hallmark of obligate intracellular pathogens related to chlamydiae and rickettsiae. These proteins catalyze the highly specific exchange of bacterial ADP against host ATP and thus allow bacteria to exploit their hosts' energy pool, a process also referred to as energy parasitism. The genome sequence of the obligate intracellular pathogen Lawsonia intracellularis (Deltaproteobacteria), responsible for one of the most economically important diseases in the swine industry worldwide, revealed the presence of a putative ATP/ADP translocase most similar to known ATP/ADP translocases of chlamydiae and rickettsiae (around 47% amino acid sequence identity). The gene coding for the putative ATP/ADP translocase of L. intracellularis (L. intracellularis nucleotide transporter 1 [NTT1(Li)]) was cloned and expressed in the heterologous host Escherichia coli. The transport properties of NTT1(Li) were determined by measuring the uptake of radioactively labeled substrates by E. coli. NTT1(Li) transported ATP in a counterexchange mode with ADP in a highly specific manner; the substrate affinities determined were 236.3 (+/- 36.5) microM for ATP and 275.2 (+/- 28.1) microM for ADP, identifying this protein as a functional ATP/ADP translocase. NTT1(Li) is the first ATP/ADP translocase from a bacterium not related to Chlamydiae or Rickettsiales, showing that energy parasitism by ATP/ADP translocases is more widespread than previously recognized. The occurrence of an ATP/ADP translocase in L. intracellularis is explained by a relatively recent horizontal gene transfer event with rickettsiae as donors.
authors.affiliation: Universität Wien, Department für Mikrobielle Okologie, Althanstr. 14, A-1090 Vienna, Austria.
authors.forename: Stephan
authors.initials: S
authors.lastname: Schmitz-Esser
authors.forename: Ilka
authors.initials: I
authors.lastname: Haferkamp
authors.forename: Silvia
authors.initials: S
authors.lastname: Knab
authors.forename: Thomas
authors.initials: T
authors.lastname: Penz
authors.forename: Michelle
authors.initials: M
authors.lastname: Ast
authors.forename: Christian
authors.initials: C
authors.lastname: Kohl
authors.forename: Michael
authors.initials: M
authors.lastname: Wagner
authors.forename: Matthias
authors.initials: M
authors.lastname: Horn
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport / Q000502:physiology; D002855:Chromatography, Thin Layer; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005057:Eukaryotic Cells / Q000382:microbiology; D022761:Gene Transfer, Horizontal; D054884:Host-Pathogen Interactions; D007700:Kinetics; D020639:Lawsonia Bacteria / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D000226:Mitochondrial ADP, ATP Translocases / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012281:Rickettsia / Q000201:enzymology; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000226:Mitochondrial ADP, ATP Translocases