title: Insight into the proteome of the hyperthermophilic Crenarchaeon Ignicoccus hospitalis: the major cytosolic and membrane proteins.
abstract: Ignicoccus hospitalis, a hyperthermophilic, chemolithoautotrophic Crenarchaeon, is the host of Nanoarchaeum equitans. Together, they form an intimate association, the first among Archaea. Membranes are of fundamental importance for the interaction of I. hospitalis and N. equitans, as they harbour the proteins necessary for the transport of macromolecules like lipids, amino acids, and cofactors between these organisms. Here, we investigated the protein inventory of I. hospitalis cells, and were able to identify 20 proteins in total. Experimental evidence and predictions let us conclude that 11 are soluble cytosolic proteins, eight membrane or membrane-associated proteins, and a single one extracellular. The quantitatively dominating proteins in the cytoplasm (peroxiredoxin; thermosome) antagonize oxidative and temperature stress which I. hospitalis cells are exposed to at optimal growth conditions. Three abundant membrane protein complexes are found: the major protein of the outer membrane, which might protect the cell against the hostile environment, forms oligomeric complexes with pores of unknown selectivity; two other complexes of the cytoplasmic membrane, the hydrogenase and the ATP synthase, play a key role in energy production and conversion.
authors.affiliation: Centre for Electron Microscopy, Faculty for Biology and Preclinical Medicine, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany.
authors.forename: Tillmann
authors.initials: T
authors.lastname: Burghardt
authors.forename: Manfred
authors.initials: M
authors.lastname: Saller
authors.forename: Sonja
authors.initials: S
authors.lastname: Gürster
authors.forename: Daniel
authors.initials: D
authors.lastname: Müller
authors.forename: Carolin
authors.initials: C
authors.lastname: Meyer
authors.forename: Ulrike
authors.initials: U
authors.lastname: Jahn
authors.forename: Eduard
authors.initials: E
authors.lastname: Hochmuth
authors.forename: Rainer
authors.initials: R
authors.lastname: Deutzmann
authors.forename: Frank
authors.initials: F
authors.lastname: Siedler
authors.forename: Patrick
authors.initials: P
authors.lastname: Babinger
authors.forename: Reinhard
authors.initials: R
authors.lastname: Wirth
authors.forename: Harald
authors.initials: H
authors.lastname: Huber
authors.forename: Reinhard
authors.initials: R
authors.lastname: Rachel
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry*; D019295:Computational Biology; D003600:Cytosol / Q000737:chemistry; D019620:Desulfurococcaceae / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D008565:Membrane Proteins / Q000737:chemistry; D020543:Proteome / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D019843:Archaeal Proteins; D008565:Membrane Proteins; D020543:Proteome