Total dissolved zinc in the upper water column of the subarctic North East Pacific

Lohan, Maeve C.; Statham, Peter J.; Crawford, David W.

doi:10.1016/s0967-0645(02)00215-1

Cited by 106 publications

(137 citation statements)

References 38 publications

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“…Moreover, 4 pairs of PhoX and PhoD peptides were mapped to four paired reads and one pair of PhoX and PhoD was mapped to a single read (Dataset S2), indicating that PhoX and PhoD can co-occur in marine bacteria. Both PhoX and PhoD are activated by Ca 2ϩ , an abundant ion in the ocean, whereas PhoA requires Zn 2ϩ (Table S1), which often occurs at subnanomolar concentrations (18,19). The replacement of Zn 2ϩ with Ca 2ϩ could be an important factor in the selection of PhoX and PhoD over PhoA in the ocean.…”

Section: Resultsmentioning

confidence: 99%

Subcellular localization of marine bacterial alkaline phosphatases

Luo¹,

Benner

Long

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

236

223

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Bacterial alkaline phosphatases (APases) are important enzymes in organophosphate utilization in the ocean. The subcellular localization of APases has significant ecological implications for marine biota but is largely unknown. The extensive metagenomic sequence databases from the Global Ocean Sampling Expedition provide an opportunity to address this question. A bioinformatics pipeline was developed to identify marine bacterial APases from the metagenomic databases, and a consensus classification algorithm was designed to predict their subcellular localizations. We identified 3,733 bacterial APase sequences (including PhoA, PhoD, and PhoX) and found that cytoplasmic (41%) and extracellular (30%) APases exceed their periplasmic (17%), outer membrane (12%), and inner membrane (0.9%) counterparts. The unexpectedly high abundance of cytoplasmic APases suggests that the transport and intracellular hydrolysis of small organophosphate molecules is an important mechanism for bacterial acquisition of phosphorus (P) in the surface ocean. On average, each marine bacterium possessed at least one suite of uptake of glycerol phosphate (ugp) genes (e.g., ugpA, ugpB, ugpC, ugpE) for dissolved organic phosphorus (DOP) transport, but only half of them had ugpQ, which hydrolyzes transported DOP, indicating that cytoplasmic APases play a role in hydrolyzing transported DOP. The most abundant heterotrophic marine bacteria, ␣-and ␥-Proteobacteria, might hydrolyze DOP outside the cytoplasmic membrane, but the former could also transport and hydrolyze DOP in the cytoplasm. The abundant extracellular APases could provide bioavailable P for organisms that cannot directly access organophosphates, and thereby increase marine biological productivity and diversity.PhoD ͉ PhoX ͉ PhoA ͉ uptake of glycerol phosphate ͉ protein localization

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Section: Resultsmentioning

confidence: 99%

Subcellular localization of marine bacterial alkaline phosphatases

Luo¹,

Benner

Long

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

236

223

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“…One cluster (cluster 9, SYNW2477-SYNW2485) includes genes for a predicted Zn 2 þ ABC transport system, a ferredoxin-nitrite reductase, a putative cyanate transporter and four conserved hypothetical genes of unknown function. Zn is found at subnanomolar concentrations in surface waters of the Pacific and Atlantic Oceans yet it is unclear whether this element limits phytoplankton growth (Lohan et al, 2002). In cyanobacteria, Zn is required for the activity of carbonic anhydrase as well as a range of metalloproteins involved in many aspects of metabolism (Blindauer, 2008).…”

Section: Resultsmentioning

confidence: 99%

PtrA is required for coordinate regulation of gene expression during phosphate stress in a marine Synechococcus

et al. 2010

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Previous microarray analyses have shown a key role for the two-component system PhoBR (SYNW0947, SYNW0948) in the regulation of P transport and metabolism in the marine cyanobacterium Synechococcus sp. WH8102. However, there is some evidence that another regulator, SYNW1019 (PtrA), probably under the control of PhoBR, is involved in the response to P depletion. PtrA is a member of the cAMP receptor protein transcriptional regulator family that shows homology to NtcA, the global nitrogen regulator in cyanobacteria. To define the role of this regulator, we constructed a mutant by insertional inactivation and compared the physiology of wild-type Synechcococcus sp. WH8102 with the ptrA mutant under P-replete and P-stress conditions. In response to P stress the ptrA mutant failed to upregulate phosphatase activity. Microarrays and quantitative RT-PCR indicate that a subset of the Pho regulon is controlled by PtrA, including two phosphatases, a predicted phytase and a gene of unknown function psip1 (SYNW0165), all of which are highly upregulated during P limitation. Electrophoretic mobility shift assays indicate binding of overexpressed PtrA to promoter sequences upstream of the induced genes. This work suggests a two-tiered response to P depletion in this strain, the first being PhoBdependent induction of high-affinity PO 4 transporters, and the second the PtrA-dependent induction of phosphatases for scavenging organic P. The levels of numerous other transcripts are also directly or indirectly influenced by PtrA, including those involved in cell-surface modification, metal uptake, photosynthesis, stress responses and other metabolic processes, which may indicate a wider role for PtrA in cellular regulation in marine picocyanobacteria.

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“…The requirement of Ca 2 þ instead of Zn 2 þ for PhoX catalytic activity has probably been a major factor in its selection over PhoA in marine environments, where Zn 2 þ often occurs at subnanomolar concentrations (Lohan et al, 2002). Indeed, replacement of Zn 2 þ by other elements has also been observed in other metalloenzymes as an adaptative response to oligotrophic conditions (Morel and Price, 2003).…”

Section: Analysis Of Metatranscriptomic Databasesmentioning

confidence: 99%

The alkaline phosphatase PhoX is more widely distributed in marine bacteria than the classical PhoA

2009

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Phosphorus (P) is a vital nutrient for all living organisms and may control the growth of bacteria in the ocean. Bacteria induce alkaline phosphatases when inorganic phosphate (Pi) is insufficient to meet their P-requirements, and therefore bulk alkaline phosphatase activity measurements have been used to assess the P-status of microbial assemblages. In this study, the molecular basis of marine bacterial phosphatases and their potential role in the environment were investigated. We found that only a limited number of homologs to the classical Escherichia coli alkaline phosphatase (PhoA) were present in marine isolates in the Bacteroidetes and γ-proteobacteria lineages. In contrast, PhoX, a recently described phosphatase, was widely distributed among diverse bacterial taxa, including Cyanobacteria, and frequently found in the marine metagenomic Global Ocean Survey database. These taxa included ecologically important groups such as Roseobacter and Trichodesmium. PhoX was induced solely upon P-starvation and accounted for approximately 90% of the phosphatase activity in the model marine bacterium Silicibacter pomeroyi. Analysis of the available transcriptomic datasets and their corresponding metagenomes indicated that PhoX is more abundant than PhoA in oligotrophic marine environments such as the North Pacific Subtropical Gyre. Those analyses also revealed that PhoA may be important when Bacteroidetes are abundant, such as in algal bloom episodes. However, PhoX appears to be much more widespread. Its identification as a gene that mediates organic P acquisition in ecologically important groups, and as a marker of Pi-stress, constitutes an important step toward a better understanding of the marine P cycle.

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Total dissolved zinc in the upper water column of the subarctic North East Pacific

Cited by 106 publications

References 38 publications

Subcellular localization of marine bacterial alkaline phosphatases

Subcellular localization of marine bacterial alkaline phosphatases

PtrA is required for coordinate regulation of gene expression during phosphate stress in a marine Synechococcus

The alkaline phosphatase PhoX is more widely distributed in marine bacteria than the classical PhoA

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