title: The protein interaction network of a taxis signal transduction system in a halophilic archaeon.
abstract: BACKGROUND
  The taxis signaling system of the extreme halophilic archaeon Halobacterium (Hbt.) salinarum differs in several aspects from its model bacterial counterparts Escherichia coli and Bacillus subtilis. We studied the protein interactions in the Hbt. salinarum taxis signaling system to gain an understanding of its structure, to gain knowledge about its known components and to search for new members.
  
  
  RESULTS
  The interaction analysis revealed that the core signaling proteins are involved in different protein complexes and our data provide evidence for dynamic interchanges between them. Fifteen of the eighteen taxis receptors (halobacterial transducers, Htrs) can be assigned to four different groups depending on their interactions with the core signaling proteins. Only one of these groups, which contains six of the eight Htrs with known signals, shows the composition expected for signaling complexes (receptor, kinase CheA, adaptor CheW, response regulator CheY). From the two Hbt. salinarum CheW proteins, only CheW1 is engaged in signaling complexes with Htrs and CheA, whereas CheW2 interacts with Htrs but not with CheA. CheY connects the core signaling structure to a subnetwork consisting of the two CheF proteins (which build a link to the flagellar apparatus), CheD (the hub of the subnetwork), two CheC complexes and the receptor methylesterase CheB.
  
  
  CONCLUSIONS
  Based on our findings, we propose two hypotheses. First, Hbt. salinarum might have the capability to dynamically adjust the impact of certain Htrs or Htr clusters depending on its current needs or environmental conditions. Secondly, we propose a hypothetical feedback loop from the response regulator to Htr methylation made from the CheC proteins, CheD and CheB, which might contribute to adaptation analogous to the CheC/CheD system of B. subtilis.
authors.affiliation: Department of Membrane Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany. m.schlesner@dkfz-heidelberg.de
authors.forename: Matthias
authors.initials: M
authors.lastname: Schlesner
authors.forename: Arthur
authors.initials: A
authors.lastname: Miller
authors.forename: Hüseyin
authors.initials: H
authors.lastname: Besir
authors.forename: Michalis
authors.initials: M
authors.lastname: Aivaliotis
authors.forename: Judith
authors.initials: J
authors.lastname: Streif
authors.forename: Beatrix
authors.initials: B
authors.lastname: Scheffer
authors.forename: Frank
authors.initials: F
authors.lastname: Siedler
authors.forename: Dieter
authors.initials: D
authors.lastname: Oesterhelt
mesh_terms: D002633:Chemotaxis; D019848:Gene Expression Regulation, Archaeal; D006217:Halobacterium / Q000235:genetics / Q000502:physiology*; D025941:Protein Interaction Mapping; D060066:Protein Interaction Maps; D015398:Signal Transduction