title: Intracellular localization of membrane-bound ATPases in the compartmentalized anammox bacterium 'Candidatus Kuenenia stuttgartiensis'.
abstract: Anaerobic ammonium-oxidizing (anammox) bacteria are divided into three compartments by bilayer membranes (from out- to inside): paryphoplasm, riboplasm and anammoxosome. It is proposed that the anammox reaction is performed by proteins located in the anammoxosome and on its membrane giving rise to a proton-motive-force and subsequent ATP synthesis by membrane-bound ATPases. To test this hypothesis, we investigated the location of membrane-bound ATPases in the anammox bacterium 'Candidatus Kuenenia stuttgartiensis'. Four ATPase gene clusters were identified in the K. stuttgartiensis genome: one typical F-ATPase, two atypical F-ATPases and a prokaryotic V-ATPase. K. stuttgartiensis transcriptomic and proteomic analysis and immunoblotting using antisera directed at catalytic subunits of the ATPase gene clusters indicated that only the typical F-ATPase gene cluster most likely encoded a functional ATPase under these cultivation conditions. Immunogold localization showed that the typical F-ATPase was predominantly located on both the outermost and anammoxosome membrane and to a lesser extent on the middle membrane. This is consistent with the anammox physiology model, and confirms the status of the outermost cell membrane as cytoplasmic membrane. The occurrence of ATPase in the anammoxosome membrane suggests that anammox bacteria have evolved a prokaryotic organelle; a membrane-bounded compartment with a specific cellular function: energy metabolism.
authors.affiliation: Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands. l.vanniftrik@science.ru.nl
authors.forename: Laura
authors.initials: L
authors.lastname: van Niftrik
authors.forename: Mary
authors.initials: M
authors.lastname: van Helden
authors.forename: Silke
authors.initials: S
authors.lastname: Kirchen
authors.forename: Elly G
authors.initials: EG
authors.lastname: van Donselaar
authors.forename: Harry R
authors.initials: HR
authors.lastname: Harhangi
authors.forename: Richard I
authors.initials: RI
authors.lastname: Webb
authors.forename: John A
authors.initials: JA
authors.lastname: Fuerst
authors.forename: Huub J M
authors.initials: HJ
authors.lastname: Op den Camp
authors.forename: Mike S M
authors.initials: MS
authors.lastname: Jetten
authors.forename: Marc
authors.initials: M
authors.lastname: Strous
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000693:Anaerobiosis; D001419:Bacteria / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D021381:Protein Transport; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D000644:Quaternary Ammonium Compounds; D000251:Adenosine Triphosphatases