title: Global gene expression of Prochlorococcus ecotypes in response to changes in nitrogen availability.
abstract: Nitrogen (N) often limits biological productivity in the oceanic gyres where Prochlorococcus is the most abundant photosynthetic organism. The Prochlorococcus community is composed of strains, such as MED4 and MIT9313, that have different N utilization capabilities and that belong to ecotypes with different depth distributions. An interstrain comparison of how Prochlorococcus responds to changes in ambient nitrogen is thus central to understanding its ecology. We quantified changes in MED4 and MIT9313 global mRNA expression, chlorophyll fluorescence, and photosystem II photochemical efficiency (Fv/Fm) along a time series of increasing N starvation. In addition, the global expression of both strains growing in ammonium-replete medium was compared to expression during growth on alternative N sources. There were interstrain similarities in N regulation such as the activation of a putative NtcA regulon during N stress. There were also important differences between the strains such as in the expression patterns of carbon metabolism genes, suggesting that the two strains integrate N and C metabolism in fundamentally different ways.
authors.affiliation: Department of Biology, MIT/WHOI Joint Program in Oceanography, Cambridge, MA, USA.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Tolonen
authors.forename: John
authors.initials: J
authors.lastname: Aach
authors.forename: Debbie
authors.initials: D
authors.lastname: Lindell
authors.forename: Zackary I
authors.initials: ZI
authors.lastname: Johnson
authors.forename: Trent
authors.initials: T
authors.lastname: Rector
authors.forename: Robert
authors.initials: R
authors.lastname: Steen
authors.forename: George M
authors.initials: GM
authors.lastname: Church
authors.forename: Sallie W
authors.initials: SW
authors.lastname: Chisholm
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D002244:Carbon / Q000378:metabolism; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics; D004463:Ecology; D004734:Energy Metabolism; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D009584:Nitrogen / Q000378:metabolism*; D009792:Oceans and Seas; D009876:Operon; D051922:PII Nitrogen Regulatory Proteins / Q000502:physiology; D045332:Photosystem II Protein Complex / Q000502:physiology; D048929:Prochlorococcus / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D012808:Sigma Factor / Q000502:physiology; D013045:Species Specificity; D014157:Transcription Factors / Q000502:physiology; D014871:Water Microbiology
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D051922:PII Nitrogen Regulatory Proteins; D045332:Photosystem II Protein Complex; D012808:Sigma Factor; D014157:Transcription Factors; C404143:PIID regulatory protein, Bacteria; D002244:Carbon; D009584:Nitrogen