scholarly journals One enzyme many faces: alkaline phosphatase-based phosphorus-nutrient strategies and the regulatory cascade revealed by CRISPR/Cas9 gene knockout

2020 ◽  
Author(s):  
Kaidian Zhang ◽  
Zhi Zhou ◽  
Jierui Wang ◽  
Jiashun Li ◽  
Xin Lin ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Carbon Fixation ◽  
Gene Knockout ◽  
Marine Phytoplankton ◽  
Ammonium Uptake ◽  
P Availability ◽  
Regulatory Cascade ◽  
Substrate Specialization ◽  
Future Warming ◽  
Global Oceans

AbstractPhosphorus (P) is an essential macronutrient for marine phytoplankton responsible for ∼50% of global carbon fixation. As P availability is variable and likely will decrease in future warming oceans, phytoplankton growth will be constrained by their strategies to scavenge dissolved organophosphate. To enhance our mechanistic understanding of these strategies, here we employ CRISPR/Cas9 to create mutants of alkaline phosphatase (AP) PhoA and PhoD and a putative regulator in the diatom model Phaeodactylum tricornutum, coupled with transcriptomic profiling to interrogate their modes of function and P- regulatory network. Results indicate that these two AP isoforms are differentiated in subcellular localization and substrate specialization, and are mutually compensatory and replaceable. Further analyses reveal a regulatory cascade of P scavenging and potential roles of AP in iron and ammonium uptake as well as diverse metabolic pathways. These findings have important implications in how phytoplankton community will respond to future changing microenvironments of global oceans.

scholarly journals Non-Conventional Metal Ion Cofactor Requirement of Dinoflagellate Alkaline Phosphatase and Translational Regulation by Phosphorus Limitation

2019 ◽  
Vol 7 (8) ◽  
pp. 232 ◽  
Author(s):  
Xin Lin ◽  
Chentao Guo ◽  
Ling Li ◽  
Tangcheng Li ◽  
Senjie Lin
Keyword(s):  
Alkaline Phosphatase ◽  
Metal Ion ◽  
Translational Regulation ◽  
Organic Phosphorus ◽  
Niche Differentiation ◽  
Phosphorus Limitation ◽  
Marine Phytoplankton ◽  
Phosphate Limitation ◽  
Dissolved Organic Phosphorus ◽  
Metal Cofactor

Alkaline phosphatase (AP) enables marine phytoplankton to utilize dissolved organic phosphorus (DOP) when dissolved inorganic phosphate (DIP) is depleted in the ocean. Dinoflagellate AP (Dino-AP) represents a newly classified atypical type of AP, PhoAaty. Despite While being a conventional AP, PhoAEC is known to recruit Zn2+ and Mg2+ in the active center, and the cofactors required by PhoAaty have been contended and remain unclear. In this study, we investigated the metal ion requirement of AP in five dinoflagellate species. After AP activity was eliminated by using EDTA to chelate metal ions, the enzymatic activity could be recovered by the supplementation of Ca2+, Mg2+ and Mn2+ in all cases but not by that of Zn2+. Furthermore, the same analysis conducted on the purified recombinant ACAAP (AP of Amphidinium carterae) verified that the enzyme could be activated by Ca2+, Mg2+, and Mn2+ but not Zn2+. We further developed an antiserum against ACAAP, and a western blot analysis using this antibody showed a remarkable up-regulation of ACAAP under a phosphate limitation, consistent with elevated AP activity. The unconventional metal cofactor requirement of Dino-AP may be an adaptation to trace metal limitations in the ocean, which warrants further research to understand the niche differentiation between dinoflagellates and other phytoplankton that use Zn–Mg AP in utilizing DOP.

scholarly journals SPX-related genes regulate phosphorus homeostasis in the marine phytoplankton, Phaeodactylum tricornutum

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Kaidian Zhang ◽  
Zhi Zhou ◽  
Jiashun Li ◽  
Jingtian Wang ◽  
Liying Yu ◽  
...  
Keyword(s):  
Stress Responses ◽  
Phaeodactylum Tricornutum ◽  
Response Regulator ◽  
P Uptake ◽  
Negative Regulator ◽  
Marine Phytoplankton ◽  
Alkaline Phosphatases ◽  
Phosphate Starvation Response ◽  
Essential Nutrient ◽  
Global Oceans

AbstractPhosphorus (P) is an essential nutrient for marine phytoplankton. Maintaining intracellular P homeostasis against environmental P variability is critical for phytoplankton, but how they achieve this is poorly understood. Here we identify a SPX gene and investigate its role in Phaeodactylum tricornutum. SPX knockout led to significant increases in the expression of phosphate transporters, alkaline phosphatases (the P acquisition machinery) and phospholipid hydrolases (a mechanism to reduce P demand). These demonstrate that SPX is a negative regulator of both P uptake and P-stress responses. Furthermore, we show that SPX regulation of P uptake and metabolism involves a phosphate starvation response regulator (PHR) as an intermediate. Additionally, we find the SPX related genes exist and operate across the phytoplankton phylogenetic spectrum and in the global oceans, indicating its universal importance in marine phytoplankton. This study lays a foundation for better understanding phytoplankton adaptation to P variability in the future changing oceans.

D-alanine metabolism via D-Ala aminotransferase by marine Gammaproteobacteria , Pseudoalteromonas sp. CF6-2

2021 ◽  
Author(s):  
Yang Yu ◽  
Jie Yang ◽  
Zhao-Jie Teng ◽  
Li-Yuan Zheng ◽  
Qi Sheng ◽  
...  
Keyword(s):  
Amino Acid ◽  
Marine Bacteria ◽  
Gene Knockout ◽  
Underlying Mechanism ◽  
Dominant Group ◽  
Seawater Samples ◽  
Underlying Mechanisms ◽  
Biochemical Analyses ◽  
Global Oceans ◽  
Shed Light

As the most abundant D-amino acid (DAA) in the ocean, D-alanine (D-Ala) is a key component of peptidoglycan in bacterial cell wall. However, the underlying mechanisms of bacterial metabolization of D-Ala through microbial food web remain largely unknown. In this study, the metabolism of D-Ala by marine bacterium Pseudoalteromonas sp. CF6-2 was investigated. Based on genomic, transcriptional and biochemical analyses combined with gene knockout, D-Ala aminotransferase was found to be indispensable for the catabolism of D-Ala in strain CF6-2. Investigation on other marine bacteria also showed that D-Ala aminotransferase gene is a reliable indicator for their ability to utilize D-Ala. Bioinformatic investigation revealed that D-Ala aminotransferase sequences are prevalent in genomes of marine bacteria and metagenomes, especially in seawater samples, and Gammaproteobacteria represents the predominant group containing D-Ala aminotransferase. Thus, Gammaproteobacteria is likely the dominant group to utilize D-Ala via D-Ala aminotransferase to drive the recycling and mineralization of D-Ala in the ocean. IMPORTANCE As the most abundant D-amino acid in the ocean, D-Ala is a component of marine DON (Dissolved organic nitrogen) pool. However, the underlying mechanism of bacterial metabolization of D-Ala to drive the recycling and mineralization of D-Ala in the ocean is still largely unknown. The results in this study showed that D-Ala aminotransferase is specific and indispensable for D-Ala catabolism in marine bacteria, and that marine bacteria containing D-Ala aminotransferase genes are predominantly Gammaproteobacteria widely distributed in global oceans. This study reveals marine D-Ala utilizing bacteria and the mechanism of their metabolization of D-Ala. The results shed light on the mechanisms of recycling and mineralization of D-Ala driven by bacteria in the ocean, which are helpful in understanding oceanic microbial-mediated nitrogen cycle.

Response of marine phytoplankton to nitrogen deficiency: Decreased nitrate uptake vs enhanced ammonium uptake

1982 ◽  
Vol 70 (1) ◽  
pp. 13-19 ◽  
Author(s):  
Q. Dortch ◽  
J. R. Clayton ◽  
S. S. Thoreson ◽  
S. L. Bressler ◽  
S. I. Ahmed
Keyword(s):  
Nitrate Uptake ◽  
Nitrogen Deficiency ◽  
Marine Phytoplankton ◽  
Ammonium Uptake

scholarly journals Detection and quantification of alkaline phosphatase in single cells of phosphorus-starved marine phytoplankton

1998 ◽  
Vol 164 ◽  
pp. 21-35 ◽  
Author(s):  
S González-Gil ◽  
BA Keafer ◽  
RVM Jovine ◽  
A Aguilera ◽  
S Lu ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Single Cells ◽  
Marine Phytoplankton ◽  
Detection And Quantification

scholarly journals Bioprocess Optimization for the Production of Arthrospira (Spirulina) platensis Biomass Enriched in the Enzyme Alkaline Phosphatase

2021 ◽  
Vol 8 (10) ◽  
pp. 142
Author(s):  
Giorgos Markou
Keyword(s):  
Alkaline Phosphatase ◽  
Single Cell ◽  
Protein Content ◽  
Fold Increase ◽  
Arthrospira Platensis ◽  
P Availability ◽  
Alp Activity ◽  
P Limitation ◽  
Protein Rich ◽  
Enzyme Alkaline Phosphatase

The enzyme alkaline phosphatase (ALP) is gaining interest because it exerts bioactive properties and may be a potentially important therapeutic agent for many disorders and diseases. Microalgae are considered an important novel source for the production of diverse bio-compounds and are gaining momentum as functional foods/feeds supplements. So far, studies for the production of ALP are limited to mammalian and partly to some heterotrophic microbial sources after its extraction and/or purification. Methods: Arthrospira was cultivated under P-limitation bioprocess and the effect of the P-limitation degree on the ALP enrichment was studied. The aim of this work was to optimize the cultivation of the edible and generally-recognized-as-safe (GRAS) cyanobacterium Arthrospira platensis for the production of single-cell (SC) biomass enriched in ALP as a potential novel functional diet supplement. Results: The results revealed that the relationship between intracellular-P and single-cell alkaline phosphatase (SC-ALP) activity was inverse; SC-ALP activity was the highest (around 50 U g−1) when intracellular-P was the lowest possible (around 1.7 mg-P g−1) and decreased gradually as P availability increased reaching around 0.5 U g−1 in the control cultures. Under the strongest P-limited conditions, a more than 100-fold increase in SC-ALP activity was obtained; however, protein content of A. platensis decreased significantly (around 22–23% from 58%). Under a moderate P-limitation degree (at intracellular-P of 3.6 mg-P g−1), there was a relatively high SC-ALP activity (>28 U g−1) while simultaneously, a relative high protein content (46%) was attained, which reflects the possibility to produce A. platensis enriched in ALP retaining though its nutritional value as a protein rich biomass source. The paper presents also results on how several parameters of the ALP activity assay, such as pH, temperature etc., and post-harvest treatment (hydrothermal treatment and biomass drying), influence the SC-ALP activity.

scholarly journals Undocumented potential for primary productivity in a globally-distributed bacterial photoautotroph

2017 ◽  
Author(s):  
E.D. Graham ◽  
J.F. Heidelberg ◽  
B.J. Tully
Keyword(s):  
Microbial Communities ◽  
Mediterranean Sea ◽  
East Africa ◽  
Primary Productivity ◽  
North Pacific ◽  
Carbon Fixation ◽  
The North ◽  
Global Oceans ◽  
Globally Distributed ◽  
The North Pacific

AbstractAerobic anoxygenic phototrophs (AAnPs) are common in the global oceans and are associated with photoheterotrophic activity. To date, AAnPs have not been identified in the surface ocean that possess the potential for carbon fixation. Using the Tara Oceans metagenomic dataset, we have reconstructed draft genomes of four bacteria that possess the genomic potential for anoxygenic phototrophy, carbon fixation via the Calvin-Benson-Bassham cycle, and the oxidation of sulfite and thiosulfate. Forming a monophyletic clade within the Alphaproteobacteria and lacking cultured representatives, the organisms compose minor constituents of local microbial communities (0.1-1.0%), but are globally distributed, present in multiple samples from the North Pacific, Mediterranean Sea, the East Africa Coastal Province, and the South Atlantic. These organisms represent a shift in our understanding of microbially-mediated photoautotrophy in the global oceans and provide a previously undiscovered route of primary productivity.Significance StatementIn examining the genomic content of organisms collected during the Tara Oceans expedition, we have identified a novel clade within the Alphaproteobacteria that has the potential for photoautotrophy. Based on genome observations, these organisms have the potential to couple inorganic sulfur compounds as electron donors to fix carbon into biomass. They are globally distributed, present in samples from the North Pacific, Mediterranean Sea, East Africa Coastal Current, and the South Atlantic. This discovery may require re-examination of the microbial communities in the global ocean to understand and constrain the impacts of this group of organisms on the global carbon cycle.

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