title: Comparative metaproteomics reveals ocean-scale shifts in microbial nutrient utilization and energy transduction.
abstract: Bacteria and Archaea play critical roles in marine energy fluxes and nutrient cycles by incorporating and redistributing dissolved organic matter and inorganic nutrients in the oceans. How these microorganisms do this work at the level of the expressed protein is known only from a few studies of targeted lineages. We used comparative membrane metaproteomics to identify functional responses of communities to different nutrient concentrations on an oceanic scale. Comparative analyses of microbial membrane fractions revealed shifts in nutrient utilization and energy transduction along an environmental gradient in South Atlantic surface waters, from a low-nutrient gyre to a highly productive coastal upwelling region. The dominant membrane proteins identified (19%) were TonB-dependent transporters (TBDTs), which are known to utilize a proton motive force to transport nutrients across the outer membrane of Gram-negative bacteria. The ocean-wide importance of TonB-dependent nutrient acquisition in marine bacteria was unsuspected. Diverse light-harvesting rhodopsins were detected in membrane proteomes from every sample. Proteomic evidence of both TBDTs and rhodopsins in the same lineages suggest that phototrophic bacterioplankton have the potential to use energy from light to fuel transport activities. We also identified viral proteins in every sample and archaeal ammonia monooxygenase proteins in the upwelling region, suggesting that Archaea are important nitrifiers in nutrient-rich surface waters.
authors.affiliation: Center for Environmental Genomics, University of Washington, Seattle, WA, USA. morrisrm@u.washington.edu
authors.forename: Robert M
authors.initials: RM
authors.lastname: Morris
authors.forename: Brook L
authors.initials: BL
authors.lastname: Nunn
authors.forename: Christian
authors.initials: C
authors.lastname: Frazar
authors.forename: David R
authors.initials: DR
authors.lastname: Goodlett
authors.forename: Ying S
authors.initials: YS
authors.lastname: Ting
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Rocap
mesh_terms: D001105:Archaea / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism*; D019843:Archaeal Proteins / Q000032:analysis; D001267:Atlantic Ocean; D001419:Bacteria / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism*; D001426:Bacterial Proteins / Q000032:analysis; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000032:analysis; D056186:Metagenomics; D040901:Proteomics; D012623:Seawater / Q000382:microbiology* / Q000821:virology
chemical_list: D019843:Archaeal Proteins; D001426:Bacterial Proteins; D008565:Membrane Proteins