Proteome Response of a Metabolically Flexible Anoxygenic Phototroph to Fe(II) Oxidation

摘要: The oxidation of Fe(II) by anoxygenic photosynthetic bacteria was likely a key contributor to Earth's biosphere prior the evolution oxygenic photosynthesis and is still found in diverse range modern environments. All known phototrophic oxidizers can utilize wide substrates, thus making them very metabolically flexible. However, underlying adaptations required oxidize Fe(II), potential stressor, are not completely understood. We used combination quantitative proteomics cryogenic transmission electron microscopy (cryo-TEM) compare cells Rhodopseudomonas palustris TIE-1 grown photoautotrophically with or H2 photoheterotrophically acetate. observed unique proteome profiles for each condition, differences primarily driven carbon source. these were related fixation but growth light harvesting processes, such as pigment synthesis. Cryo-TEM showed stunted development membranes photoautotrophic cultures. Growth on characterized response typical iron homeostasis, which included an increased abundance proteins metal efflux (particularly copper) decreased import proteins, including siderophore receptors, no evidence further stressors, oxidative damage. This study suggests that main challenge facing comes from limitations imposed autotrophy, and, once this overcome, stress be mitigated using management mechanisms common (e.g., control influx efflux).IMPORTANCE cycling between redox states leads precipitation dissolution minerals, turn impact other major biogeochemical cycles, those carbon, nitrogen, phosphorus sulfur. Anoxygenic phototrophs one few drivers anoxic environments thought contribute significantly both ancient These organisms thrive at high concentrations, yet tolerate stresses associated unclear. Despite general consensus concentrations pose numerous organisms, our large-scale model phototroph demonstrates homeostasis strategies adequate manage this. bulk inorganic Such global overview adaptation provides valuable insights into physiology biogeochemically important may many challenges previously thought.