Transcriptional Response to Sulfur Limitation in Pelagibacter ubique
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ABSTRACT:
ORGANISM(S): Candidatus Pelagibacter ubique HTCC1062 Candidatus Pelagibacter ubique HTCC1002 Candidatus Pelagibacter sp. HTCC7211
PROVIDER: GSE31630 | GEO | 2016/06/26
SECONDARY ACCESSION(S): PRJNA145551
REPOSITORIES: GEO
Similar Datasets
Project description:Candidatus Pelagibacter ubique is the most abundant marine microorganism, but is unable to utilize inorganic sulfur compounds that are plentiful in the ocean. To investigate how these cells adapt to organic sulfur limitation, batch cultures were grown in defined media containing either limiting or non-limiting amounts of dimethylsulfoniopropionate (DMSP) as the sole sulfur source. Protein and mRNA expression were measured during exponential growth, immediately prior to stationary phase, and in late stationary phase. Two distinct responses were observed: one as DMSP approached exhaustion, and another after the DMSP supply was depleted. The first response was characterized by increased transcription and translation of all Ca. P. ubique genes downstream of previously confirmed S-adenosyl methionine (SAM) riboswitches: bhmT, mmuM, and metY. These genes were up to 33 times more abundant during low DMSP conditions and shunt all available sulfur to methionine. The osmotically inducible organic hydroperoxidase OsmC was the most up-regulated protein as DMSP (an osmolyte) became scarce. The second response, during sulfur-depleted stationary phase, saw increased transcription of the heme c shuttle ccmC and two small genes of unknown function (SAR11_1163 and SAR11_1164) which were 6-10 times higher in sulfur-starved cultures. No known membrane transporters were up-regulated in response to sulfur limitation, suggesting that this bacterium's strategy for coping with sulfur stress focuses on intracellularly redistributing, rather than importing, organic sulfur compounds. This supports the conclusion that the few organosulfur molecules that Ca. P. ubique is able to metabolize are rarely limiting in the marine environment. Batch cultures of P. ubique were grown in a defined arificial seawater media. Five cultures were amended with a limiting concentration of DMSP as the sole sulfur source and another four control cultures were amended with a non-limiting DMSP concentration. Cultures were harvested for microarray analyses at multiple timepoints for the purpose of observing differences in gene expression related to sulfur limitation. Proteomic analyses were conducted in parallel and are available at https://www.ebi.ac.uk/pride/archive/projects/PXD003672 .
2016-06-26 | E-GEOD-31630 | biostudies-arrayexpress
Project description:Dimethylsufoniopropionate (DMSP) is an important and abundant organic sulfur compound and an important substrate for marine bacterioplankton. The Roseobacter clade of marine alpha-proteobacteria, including Silicibacter pomeroyi strain DSS3, are known to be a key phylogenetic group involved in DMSP degradaton. The fate of DMSP has important implications for the global sulfur cycle, but the genes involved in this process and their regulation are largely unknown. S. pomeroyi is capable of performing two major pathways of DMSP degradation, making it an interesting model organism. Based on the full genome sequence of this strain we designed an oligonucleotide-based microarray for the detection of transcripts of nearly all genes. The array was used to study the transcriptional response of S. pomeroyi cultures to additions of DMSP or Acetate in a time series experiment. We identified a number of DMSP-upregulated genes that could be assigned to potential roles in the metabolization of DMSP. DMSP also affected the transcription of other groups of genes, including genes for transport and metabolization of peptides, amino-acids and polyamines. High DMSP concentrations may be a chemical signal indicating phytoplankton abundance and elicit a regulatory response aimed at making maximum use of the available nutrients under these conditions. Keywords: Microarray, marine bacterium, messenger RNA, transcription, sulfur metabolism
2007-12-09 | GSE5480 | GEO
Project description:The fraction of dissolved dimethylsulfoniopropionate (DMSPd) converted by marine bacterioplankton into the climate-active gas dimethylsulfide (DMS) varies widely in the ocean, with the factors that determine this value still largely unknown. One current hypothesis is that the ratio of DMS formation:DMSP demethylation is determined by DMSP availability, with 'availability' in both an absolute sense (i.e., concentration in seawater) and in a relative sense (i.e., proportionally to other labile organic S compounds) being proposed as the critical factor. We investigated these models during an experimentally-induced phytoplankton bloom using an environmental microarray targeting DMSP-related gene expression in the Roseobacter group, a taxon of marine bacteria known to play an important role in the surface ocean sulfur cycle. The array consisted of 1,578 probes to 431 genes, including those previously linked to DMSP degradation as well as core genes common in sequenced Roseobacter genomes. The prevailing pattern of Roseobacter gene expression showed depletion of DMSP-related transcripts during the peak of the bloom, despite the fact that absolute concentrations and flux of DMSP-related compounds were increasing. A likely interpretation is that DMSPd was assimilated by Roseobacter populations in proportion to its relative abundance in the organic matter pool (the “relative sense” hypothesis), and that it is not taken up in preference to other sources of labile organic sulfur or carbon produced during the bloom. The relative investment of the Roseobacter community in DMSP demethylation did not predict the fractional conversion of DMSP to DMS, however, suggesting a complex regulatory process that may involve multiple fates of DMSPd.
2010-08-05 | GSE21325 | GEO
Project description:Dimethylsufoniopropionate (DMSP) is an important and abundant organic sulfur compound and an important substrate for marine bacterioplankton. The Roseobacter clade of marine alpha-proteobacteria, including Silicibacter pomeroyi strain DSS3, are known to be a key phylogenetic group involved in DMSP degradaton. The fate of DMSP has important implications for the global sulfur cycle, but the genes involved in this process and their regulation are largely unknown. S. pomeroyi is capable of performing two major pathways of DMSP degradation, making it an interesting model organism. Based on the full genome sequence of this strain we designed an oligonucleotide-based microarray for the detection of transcripts of nearly all genes. The array was used to study the transcriptional response of S. pomeroyi cultures to additions of DMSP or Acetate in a time series experiment. We identified a number of DMSP-upregulated genes that could be assigned to potential roles in the metabolization of DMSP. DMSP also affected the transcription of other groups of genes, including genes for transport and metabolization of peptides, amino-acids and polyamines. High DMSP concentrations may be a chemical signal indicating phytoplankton abundance and elicit a regulatory response aimed at making maximum use of the available nutrients under these conditions. Keywords: Microarray, marine bacterium, messenger RNA, transcription, sulfur metabolism The array design is based on the complete genome sequence of S. pomeroyi strain DSS 3 and available from Genbank (Accession numbers CP000031 and CP000032). Probes for all identified potential genes were designed by Combimatrix using proprietary software. A total of 4161 genes out of the 4348 identified potential genes on the S. pomeroyi genome are represented on the array. When possible, two probes per gene were designed.
2007-12-09 | E-GEOD-5480 | biostudies-arrayexpress
Project description:Nitrogen is one of the major nutrients limiting microbial productivity in the ocean, and as a result marine microorganisms have evolved specialized systems for responding to nitrogen stress. The highly abundant alphaproteobacterium Candidatus Pelagibacter ubique lacks the canonical GlnB, GlnD, and NtrB/NtrC genes for regulating nitrogen assimilation. A survey of 127 Alphaproteobacteria genomes found these genes to be highly represented in free-living and pathogenic organisms with large genomes and only missing in a subset of obligate intracellular organisms and other SAR11 strains. We examined global differences in mRNA and protein expression in Ca. P. ubique strain HTCC1062 during nitrogen-limited and nitrogen-replete stationary phase to understand how this thriving organism responds to nitrogen limitation. Transporters for ammonium (AmtB), taurine (TauA), amino acids (YhdW), and opines (OccT) were all elevated in nitrogen-limited cells, indicating they devote increased resources to the assimilation of nitrogenous compounds. Enzymes for assimilating amine into glutamine (GlnA) and glutamate (AspC, GltBD) were similarly up-regulated. Differential regulation of the transcriptional regulator NtrX in the two-component signaling system NtrY/NtrX was also observed, implicating it in the control of the nitrogen starvation response. Comparisons of the transcriptome and proteome suggest that Amt is post-transcriptionally repressed during nitrogen limitation, supporting previous studies that computationally identified a novel cis-acting riboswitch upstream of this gene. These observations support the conclusion that Ca. P. ubique has an unusually simple regulatory system that enables it to increase its capacity for the uptake of nitrogenous compounds in response to nitrogen limitation. Batch cultures of P. ubique were grown in a defined arificial seawater media. Three cultures were given no nitrogen amendment, and three other cultures received an excess concentration of NH3. Cultures were harvested for microarray analyses during log and stationary phase for the purpose of observing differences in gene expression related to nitrogen limitation. Proteomic analysis was conducted in parallel and is available at http://omics.pnl.gov .
2013-09-01 | E-GEOD-37445 | biostudies-arrayexpress
Project description:Nitrogen is one of the major nutrients limiting microbial productivity in the ocean, and as a result marine microorganisms have evolved specialized systems for responding to nitrogen stress. The highly abundant alphaproteobacterium Candidatus Pelagibacter ubique lacks the canonical GlnB, GlnD, and NtrB/NtrC genes for regulating nitrogen assimilation. A survey of 127 Alphaproteobacteria genomes found these genes to be highly represented in free-living and pathogenic organisms with large genomes and only missing in a subset of obligate intracellular organisms and other SAR11 strains. We examined global differences in mRNA and protein expression in Ca. P. ubique strain HTCC1062 during nitrogen-limited and nitrogen-replete stationary phase to understand how this thriving organism responds to nitrogen limitation. Transporters for ammonium (AmtB), taurine (TauA), amino acids (YhdW), and opines (OccT) were all elevated in nitrogen-limited cells, indicating they devote increased resources to the assimilation of nitrogenous compounds. Enzymes for assimilating amine into glutamine (GlnA) and glutamate (AspC, GltBD) were similarly up-regulated. Differential regulation of the transcriptional regulator NtrX in the two-component signaling system NtrY/NtrX was also observed, implicating it in the control of the nitrogen starvation response. Comparisons of the transcriptome and proteome suggest that Amt is post-transcriptionally repressed during nitrogen limitation, supporting previous studies that computationally identified a novel cis-acting riboswitch upstream of this gene. These observations support the conclusion that Ca. P. ubique has an unusually simple regulatory system that enables it to increase its capacity for the uptake of nitrogenous compounds in response to nitrogen limitation.
2013-09-01 | GSE37445 | GEO
Project description:The fraction of dissolved dimethylsulfoniopropionate (DMSPd) converted by marine bacterioplankton into the climate-active gas dimethylsulfide (DMS) varies widely in the ocean, with the factors that determine this value still largely unknown. One current hypothesis is that the ratio of DMS formation:DMSP demethylation is determined by DMSP availability, with 'availability' in both an absolute sense (i.e., concentration in seawater) and in a relative sense (i.e., proportionally to other labile organic S compounds) being proposed as the critical factor. We investigated these models during an experimentally-induced phytoplankton bloom using an environmental microarray targeting DMSP-related gene expression in the Roseobacter group, a taxon of marine bacteria known to play an important role in the surface ocean sulfur cycle. The array consisted of 1,578 probes to 431 genes, including those previously linked to DMSP degradation as well as core genes common in sequenced Roseobacter genomes. The prevailing pattern of Roseobacter gene expression showed depletion of DMSP-related transcripts during the peak of the bloom, despite the fact that absolute concentrations and flux of DMSP-related compounds were increasing. A likely interpretation is that DMSPd was assimilated by Roseobacter populations in proportion to its relative abundance in the organic matter pool (the “relative sense” hypothesis), and that it is not taken up in preference to other sources of labile organic sulfur or carbon produced during the bloom. The relative investment of the Roseobacter community in DMSP demethylation did not predict the fractional conversion of DMSP to DMS, however, suggesting a complex regulatory process that may involve multiple fates of DMSPd. DMSP-related gene expression in the Roseobacter group was investigated using an environmental microarray. Coastal seawater from the Gulf of Mexico was collected and dispensed into 20-L microcosms. Two replicate cubitainers were amended with nutrients (N and P) to stimulate phytoplankton bloom, while two untreated cubitainers served as controls. The microcosms were incubated at 27ºC in a temperature-controlled incubator on a 12 h light/dark cycle for total of 7 days. Ten RNA samples (Day 0: 2 conditions with 1 biological replicate each; Days 2 and 4: 2 conditions with 2 biological replicates each) were prepared for microarray hybridization. After total RNA extraction, rRNAs were removed and mRNA transcripts were amplified and labeled with Alexa Fluor 647. Two technical replicates were hybridized from each RNA sample. The microarray was designed based on selected Ruegeria pomeroyi DSS-3 genes and their orthologs in 12 other sequenced Roseobacter genomes. Probes were designed from the orthologs using the Hierarchical Probe Design (HPD) algorithm.
2010-08-05 | E-GEOD-21325 | biostudies-arrayexpress
Project description:Unicellular algae, termed phytoplankton, greatly impact the marine environment by serving as the basis of marine food webs and by playing central roles in biogeochemical cycling of elements. The interactions between phytoplankton and heterotrophic bacteria affect the fitness of both partners. It is becoming increasingly understood that metabolic exchange determines the nature of such interactions, but the underlying molecular mechanisms remain underexplored. Here, we investigated the molecular and metabolic basis for the bacterial lifestyle switch, from coexistence to pathogenicity, in Sulfitobacter D7 during interactions with Emiliania huxleyi, a cosmopolitan bloom-forming phytoplankter. The interaction displays two distinct phases: first, there is a coexisting phase in which the alga grows exponentially and the bacterium grows as well. The interaction shifts to pathogenic when the virulence of Sulfitobacter D7 towards E. huxleyi is invoked upon exposure to high concentrations of algal dimethylsulfoniopropionate (DMSP), which occurs when the algae reach stationary growth or when DMSP is applied exogenously to algae in exponential growth. We aimed to unravel the response of Sulfitobacter D7 to the pathogenicity-inducing compound, DMSP, and to different algae-derived infochemicals that affect the lifestyle of the bacterium. We grew Sulfitobacter D7 in conditioned media (CM) derived from algal cultures at the different growth phases, exponential and stationary (Exp-CM and Stat-CM, respectively), in which DMSP concentration is low and high, respectively. This enabled us to separate between different phases of the interaction with E. huxleyi, i.e., Exp-CM representing the coexisting phase, and Stat-CM representing the pathogenic phase. An additional pathogenicity-inducing treatment was Exp-CM supplemented with 100 µM DMSP (herein Exp-CM+DMSP). This condition mimicked co-cultures to which we added DMSP exogenously and thus induced Sulfitobacter D7 pathogenicity, which lead to death of exponentially growing E. huxleyi. In order to identify bacterial genes that are specifically responsive to DMSP, and are not affected by other algae-derived factors, we grew Sulfitobacter D7 in defined minimal medium (MM), lacking algal metabolites, supplemented with 100 µM DMSP (herein MM+DMSP), and examined the transcriptional response. After 24 h of Sulfitobacter D7 growth in all 5 media, triplicates were taken for transcriptomic analysis. Altogether, this experimental design allowed to expand our understanding on the bacterial response to DMSP, algal infochemicals and which of these are essential for coexistence and pathogenicity.
2023-01-17 | GSE193203 | GEO
Project description:Marine phytoplankton produce ~109 tons of dimethylsulfoniopropionate (DMSP) per year, an estimated 10% of which is catabolized by bacteria through the DMSP cleavage pathway to the climatically active gas dimethyl sulfide (DMS). SAR11 Alphaproteobacteria (order Pelagibacterales), the most abundant chemoorganotrophic bacteria in the oceans, have been shown to assimilate DMSP into biomass, thereby supplying this cell’s unusual requirement for reduced sulfur. Here we report that Pelagibacter HTCC1062 produces the gas methanethiol (MeSH) and that simultaneously a second DMSP catabolic pathway, mediated by a DMSP lyase, shunts as much as 59% of DMSP uptake to DMS production. We propose a model in which the allocation of DMSP between these pathways is kinetically controlled to release DMS when the supply of DMSP exceeds cellular sulfur demands for biosynthesis. These findings suggest that DMSP supply and demand relationships can significantly control rates of oceanic DMS production.
2017-12-08 | PXD001717 | Pride
Project description:Transcriptional Response to Sulfur Limitation in Pelagibacter ubique
| PRJNA145551 | ENA