title: Proteomic characterization of cellular and molecular processes that enable the Nanoarchaeum equitans--Ignicoccus hospitalis relationship.
abstract: Nanoarchaeum equitans, the only cultured representative of the Nanoarchaeota, is dependent on direct physical contact with its host, the hyperthermophile Ignicoccus hospitalis. The molecular mechanisms that enable this relationship are unknown. Using whole-cell proteomics, differences in the relative abundance of >75% of predicted protein-coding genes from both Archaea were measured to identify the specific response of I. hospitalis to the presence of N. equitans on its surface. A purified N. equitans sample was also analyzed for evidence of interspecies protein transfer. The depth of cellular proteome coverage achieved here is amongst the highest reported for any organism. Based on changes in the proteome under the specific conditions of this study, I. hospitalis reacts to N. equitans by curtailing genetic information processing (replication, transcription) in lieu of intensifying its energetic, protein processing and cellular membrane functions. We found no evidence of significant Ignicoccus biosynthetic enzymes being transported to N. equitans. These results suggest that, under laboratory conditions, N. equitans diverts some of its host's metabolism and cell cycle control to compensate for its own metabolic shortcomings, thus appearing to be entirely dependent on small, transferable metabolites and energetic precursors from I. hospitalis.
authors.affiliation: Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Giannone
authors.forename: Harald
authors.initials: H
authors.lastname: Huber
authors.forename: Tatiana
authors.initials: T
authors.lastname: Karpinets
authors.forename: Thomas
authors.initials: T
authors.lastname: Heimerl
authors.forename: Ulf
authors.initials: U
authors.lastname: Küper
authors.forename: Reinhard
authors.initials: R
authors.lastname: Rachel
authors.forename: Martin
authors.initials: M
authors.lastname: Keller
authors.forename: Robert L
authors.initials: RL
authors.lastname: Hettich
authors.forename: Mircea
authors.initials: M
authors.lastname: Podar
mesh_terms: D019843:Archaeal Proteins / Q000378:metabolism*; D019620:Desulfurococcaceae / Q000378:metabolism* / Q000502:physiology; D046588:Nanoarchaeota / Q000378:metabolism* / Q000502:physiology; D040901:Proteomics / Q000379:methods*
chemical_list: D019843:Archaeal Proteins