title: Life on the edge: functional genomic response of Ignicoccus hospitalis to the presence of Nanoarchaeum equitans.
abstract: The marine hyperthermophilic crenarchaeon Ignicoccus hospitalis supports the propagation on its surface of Nanoarchaeum equitans, an evolutionarily enigmatic archaeon that resembles highly derived parasitic and symbiotic bacteria. The cellular and molecular mechanisms that enable this interarchaea relationship and the intimate physiologic consequences to I. hospitalis are unknown. Here, we used concerted proteomic and transcriptomic analyses to probe into the functional genomic response of I. hospitalis as N. equitans multiplies on its surface. The expression of over 97% of the genes was detected at mRNA level and over 80% of the predicted proteins were identified and their relative abundance measured by proteomics. These indicate that little, if any, of the host genomic information is silenced during growth in the laboratory. The primary response to N. equitans was at the membrane level, with increases in relative abundance of most protein complexes involved in energy generation as well as that of several transporters and proteins involved in cellular membrane stabilization. Similar upregulation was observed for genes and proteins involved in key metabolic steps controlling nitrogen and carbon metabolism, although the overall biosynthetic pathways were marginally impacted. Proliferation of N. equitans resulted, however, in selective downregulation of genes coding for transcription factors and replication and cell cycle control proteins as I. hospitalis shifted its physiology from its own cellular growth to that of its ectosymbiont/parasite. The combination of these multiomic approaches provided an unprecedented level of detail regarding the dynamics of this interspecies interaction, which is especially pertinent as these organisms are not genetically tractable.
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, TN, USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Giannone
authors.affiliation: Department of Microbiology, University of Tennessee, Knoxville, TN, USA.
authors.forename: Louie L
authors.initials: LL
authors.lastname: Wurch
authors.affiliation: Lehrstuhl für Mikrobiologie und Archaeenzentrum, Universität Regensburg, Regensburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Heimerl
authors.affiliation: 1] Oak Ridge National Laboratory, Oak Ridge, TN, USA [2] SAS Institute Inc., Cary, NC, USA.
authors.forename: Stanton
authors.initials: S
authors.lastname: Martin
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, TN, USA.
authors.forename: Zamin
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Lehrstuhl für Mikrobiologie und Archaeenzentrum, Universität Regensburg, Regensburg, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Huber
authors.affiliation: Lehrstuhl für Mikrobiologie und Archaeenzentrum, Universität Regensburg, Regensburg, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Rachel
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, TN, USA.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Hettich
authors.affiliation: 1] Oak Ridge National Laboratory, Oak Ridge, TN, USA [2] Department of Microbiology, University of Tennessee, Knoxville, TN, USA.
authors.forename: Mircea
authors.initials: M
authors.lastname: Podar
mesh_terms: D019843:Archaeal Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D019620:Desulfurococcaceae / Q000254:growth & development / Q000502:physiology*; D015870:Gene Expression; D020745:Genome, Archaeal; D056265:Microbial Interactions; D046588:Nanoarchaeota / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D040901:Proteomics
chemical_list: D019843:Archaeal Proteins