title: Proteomic and Mutant Analysis of the CO2Concentrating Mechanism of Hydrothermal Vent Chemolithoautotroph Thiomicrospira crunogena.
abstract: Many autotrophic microorganisms are likely to adapt to scarcity in dissolved inorganic carbon (DIC; CO2+ HCO3-+ CO32-) with CO2concentrating mechanisms (CCM) that actively transport DIC across the cell membrane to facilitate carbon fixation. Surprisingly, DIC transport has been well studied among cyanobacteria and microalgae only. The deep-sea vent gammaproteobacterial chemolithoautotrophThiomicrospira crunogenahas a low-DIC inducible CCM, though the mechanism for uptake is unclear, as homologs to cyanobacterial transporters are absent. To identify the components of this CCM, proteomes ofT. crunogenacultivated under low- and high-DIC conditions were compared. Fourteen proteins, including those comprising carboxysomes, were at least 4-fold more abundant under low-DIC conditions. One of these proteins was encoded byTcr_0854; strains carrying mutated copies of this gene, as well as the adjacentTcr_0853, required elevated DIC for growth. Strains carrying mutated copies ofTcr_0853andTcr_0854overexpressed carboxysomes and had diminished ability to accumulate intracellular DIC. Based on reverse transcription (RT)-PCR,Tcr_0853andTcr_0854were cotranscribed and upregulated under low-DIC conditions. TheTcr_0853-encoded protein was predicted to have 13 transmembrane helices. Given the mutant phenotypes described above,Tcr_0853andTcr_0854may encode a two-subunit DIC transporter that belongs to a previously undescribed transporter family, though it is widespread among autotrophs from multiple phyla.IMPORTANCEDIC uptake and fixation by autotrophs are the primary input of inorganic carbon into the biosphere. The mechanism for dissolved inorganic carbon uptake has been characterized only for cyanobacteria despite the importance of DIC uptake by autotrophic microorganisms from many phyla among theBacteriaandArchaeaIn this work, proteins necessary for dissolved inorganic carbon utilization in the deep-sea vent chemolithoautotrophT. crunogenawere identified, and two of these may be able to form a novel transporter. Homologs of these proteins are present in 14 phyla inBacteriaand also in one phylum ofArchaea, theEuryarchaeotaMany organisms carrying these homologs are autotrophs, suggesting a role in facilitating dissolved inorganic carbon uptake and fixation well beyond the genusThiomicrospira.
authors.affiliation: Department of Integrative Biology, University of South Florida, Tampa, Florida, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Mangiapia
authors.affiliation: Department of Integrative Biology, University of South Florida, Tampa, Florida, USA.
authors.forename: Terry-René W
authors.initials: TW
authors.lastname: Brown
authors.affiliation: Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, Florida, USA.
authors.forename: Dale
authors.initials: D
authors.lastname: Chaput
authors.affiliation: Department of Integrative Biology, University of South Florida, Tampa, Florida, USA.
authors.forename: Edward
authors.initials: E
authors.lastname: Haller
authors.affiliation: Biology Program, The Richard Stockton College of New Jersey, Pomona, New Jersey, USA.
authors.forename: Tara L
authors.initials: TL
authors.lastname: Harmer
authors.affiliation: Department of Integrative Biology, University of South Florida, Tampa, Florida, USA.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Hashemy
authors.affiliation: Department of Integrative Biology, University of South Florida, Tampa, Florida, USA.
authors.forename: Ryan
authors.initials: R
authors.lastname: Keeley
authors.affiliation: Department of Integrative Biology, University of South Florida, Tampa, Florida, USA.
authors.forename: Juliana
authors.initials: J
authors.lastname: Leonard
authors.affiliation: Department of Integrative Biology, University of South Florida, Tampa, Florida, USA.
authors.forename: Paola
authors.initials: P
authors.lastname: Mancera
authors.affiliation: Department of Integrative Biology, University of South Florida, Tampa, Florida, USA.
authors.forename: David
authors.initials: D
authors.lastname: Nicholson
authors.affiliation: Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, Florida, USA.
authors.forename: Stanley
authors.initials: S
authors.lastname: Stevens
authors.affiliation: Department of Integrative Biology, University of South Florida, Tampa, Florida, USA.
authors.forename: Pauline
authors.initials: P
authors.lastname: Wanjugi
authors.affiliation: Department of Integrative Biology, University of South Florida, Tampa, Florida, USA.
authors.forename: Tania
authors.initials: T
authors.lastname: Zabinski
authors.affiliation: Genome Science and Technology, University of Tennessee, Knoxville, and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA.
authors.forename: Chongle
authors.initials: C
authors.lastname: Pan
authors.affiliation: Department of Integrative Biology, University of South Florida, Tampa, Florida, USA kmscott@usf.edu.
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Scott
mesh_terms: D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D060086:Hydrothermal Vents / Q000382:microbiology*; D009154:Mutation; D010802:Phylogeny; D044147:Piscirickettsiaceae / Q000235:genetics / Q000378:metabolism*; D020543:Proteome
chemical_list: D020543:Proteome; D002245:Carbon Dioxide; D002244:Carbon
keywords: autotroph; bicarbonate transporter; carbon concentrating mechanism; carbon fixation; chemolithoautotroph; hydrothermal vent