A mitochondrial exopolyphosphatase activity modulated by phosphate demand in Rhipicephalus (Boophilus) microplus embryo

Campos, Eldo; Façanha, Arnoldo Rocha; Moraes, João Antônio de; Vaz, Itabajara da Silva; Masuda, Aoi; Logullo, Carlos

doi:10.1016/j.ibmb.2007.06.003

Cited by 15 publications

(31 citation statements)

References 26 publications

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“…Thereafter, the embryo becomes a multicellular organism and initiates organogenesis [29]. Previously, we have found that during egg segmentation (9th day after oviposition), a strong mitochondrial PPX activity exists [15]. Here, we provide evidence that mitochondrial membrane PPX plays a role in energy metabolism of R. microplus during embryo development.…”

Section: Resultssupporting

confidence: 51%

“…Conversely, polyP functions have not been extensively investigated in higher eukaryotes, although some functions have been described, such as activation of TOR kinase [10], involvement in blood coagulation [11], and apoptosis [12–14]. Recently, we have reported the first evidence that polyP also play key roles in arthropods and have described a mitochondrial and a nuclear exopolyphosphatase involved in metabolism during embryogenesis of the hard tick Rhipicephalus microplus [15,16]. …”

Section: Introductionmentioning

confidence: 99%

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A Mitochondrial Membrane Exopolyphosphatase Is Modulated by, and Plays a Role in, the Energy Metabolism of Hard Tick Rhipicephalus (Boophilus) microplus Embryos

Campos

Façanha

Costa

et al. 2011

IJMS

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The physiological roles of polyphosphates (polyP) recently found in arthropod mitochondria remain obscure. Here, the relationship between the mitochondrial membrane exopolyphosphatase (PPX) and the energy metabolism of hard tick Rhipicephalus microplus embryos are investigated. Mitochondrial respiration was activated by adenosine diphosphate using polyP as the only source of inorganic phosphate (Pi) and this activation was much greater using polyP3 than polyP15. After mitochondrial subfractionation, most of the PPX activity was recovered in the membrane fraction and its kinetic analysis revealed that the affinity for polyP3 was 10 times stronger than that for polyP15. Membrane PPX activity was also increased in the presence of the respiratory substrate pyruvic acid and after addition of the protonophore carbonyl cyanide-p-trifluoromethoxyphenylhydrazone. Furthermore, these stimulatory effects disappeared upon addition of the cytochrome oxidase inhibitor potassium cyanide and the activity was completely inhibited by 20 μg/mL heparin. The activity was either increased or decreased by 50% upon addition of dithiothreitol or hydrogen peroxide, respectively, suggesting redox regulation. These results indicate a PPX activity that is regulated during mitochondrial respiration and that plays a role in adenosine-5′-triphosphate synthesis in hard tick embryos.

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Section: Resultssupporting

confidence: 51%

Section: Introductionmentioning

confidence: 99%

A Mitochondrial Membrane Exopolyphosphatase Is Modulated by, and Plays a Role in, the Energy Metabolism of Hard Tick Rhipicephalus (Boophilus) microplus Embryos

Campos

Façanha

Costa

et al. 2011

IJMS

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“…The presence of poly P stored in acidocalcisomes has been extensively reported in different models [15], [23], and changes in its levels according to varied extracellular stimuli were observed [35]. Interestingly, the levels of poly P in Rhodnius acidocalcisomes tend to decrease slightly before the beginning of yolk mobilization, and a decrease in the levels of this polymer was already observed in eggs of the cattle tick Boophilus microplus [61] and the cockroach P. americana [37]. These data suggest that poly P might be widely used as Pi source for growing embryos, mainly in invertebrates, that do not store massively phosphorylated yolk proteins as phosvitins, known in vertebrate models [62].…”

Section: Discussionmentioning

confidence: 89%

Acidocalcisomes as Calcium- and Polyphosphate-Storage Compartments during Embryogenesis of the Insect Rhodnius prolixus Stahl

et al. 2011

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BackgroundThe yolk of insect eggs is a cellular domain specialized in the storage of reserve components for embryo development. The reserve macromolecules are stored in different organelles and their interactions with the embryo cells are mostly unknown. Acidocalcisomes are lysosome-related organelles characterized by their acidic nature, high electron density and large content of polyphosphate bound to several cations. In this work, we report the presence of acidocalcisome-like organelles in eggs of the insect vector Rhodnius prolixus.Methodology/Principal findingsCharacterization of the elemental composition of electron-dense vesicles by electron probe X-ray microanalysis revealed a composition similar to that previously described for acidocalcisomes. Following subcellular fractionation experiments, fractions enriched in acidocalcisomes were obtained and characterized. Immunofluorescence showed that polyphosphate polymers and the vacuolar proton translocating pyrophosphatase (V-H+-PPase, considered as a marker for acidocalcisomes) are found in the same vesicles and that these organelles are mainly localized in the egg cortex. Polyphosphate quantification showed that acidocalcisomes contain a significant amount of polyphosphate detected at day-0 eggs. Elemental analyses of the egg fractions showed that 24.5±0.65% of the egg calcium are also stored in such organelles. During embryogenesis, incubation of acidocalcisomes with acridine orange showed that these organelles are acidified at day-3 (coinciding with the period of yolk mobilization) and polyphosphate quantification showed that the levels of polyphosphate tend to decrease during early embryogenesis, being approximately 30% lower at day-3 compared to day-0 eggs.ConclusionsWe found that acidocalcisomes are present in the eggs and are the main storage compartments of polyphosphate and calcium in the egg yolk. As such components have been shown to be involved in a series of dynamic events that may control embryo growth, results reveal the potential involvement of a novel organelle in the storage and mobilization of inorganic elements to the embryo cells.

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“…PolyP has since been documented in mammalian cells [2], and has been revealed to have physiological roles [3], including regulation of vertebrate skeletal mineralization [4–7], fibrin clotting [8–10], intestinal homeostasis [11], neuronal excitability [12], innate immunity [13] and to have functions as a P2 receptor agonist [14]. PolyP is also involved in some disease conditions, including tumor proliferation [15,16], metastasis [17], cardiac necrosis or neurodegenerative processes [17–20] and energy deficiency [21–23]. …”

Section: Introductionmentioning

confidence: 99%

Positively-Charged Semi-Tunnel Is a Structural and Surface Characteristic of Polyphosphate-Binding Proteins: An In-Silico Study

et al. 2015

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Phosphate is essential for all major life processes, especially energy metabolism and signal transduction. A linear phosphate polymer, polyphosphate (polyP), linked by high-energy phosphoanhydride bonds, can interact with various proteins, playing important roles as an energy source and regulatory factor. However, polyP-binding structures are largely unknown. Here we proposed a putative polyP binding site, a positively-charged semi-tunnel (PCST), identified by surface electrostatics analyses in polyP kinases (PPKs) and many other polyP-related proteins. We found that the PCSTs in varied proteins were folded in different secondary structure compositions. Molecular docking calculations revealed a significant value for binding affinity to polyP in PCST-containing proteins. Utilizing the PCST identified in the β subunit of PPK3, we predicted the potential polyP-binding domain of PPK3. The discovery of this feature facilitates future searches for polyP-binding proteins and discovery of the mechanisms for polyP-binding activities. This should greatly enhance the understanding of the many physiological functions of protein-bound polyP and the involvement of polyP and polyP-binding proteins in various human diseases.

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A mitochondrial exopolyphosphatase activity modulated by phosphate demand in Rhipicephalus (Boophilus) microplus embryo

Cited by 15 publications

References 26 publications

A Mitochondrial Membrane Exopolyphosphatase Is Modulated by, and Plays a Role in, the Energy Metabolism of Hard Tick Rhipicephalus (Boophilus) microplus Embryos

A Mitochondrial Membrane Exopolyphosphatase Is Modulated by, and Plays a Role in, the Energy Metabolism of Hard Tick Rhipicephalus (Boophilus) microplus Embryos

Acidocalcisomes as Calcium- and Polyphosphate-Storage Compartments during Embryogenesis of the Insect Rhodnius prolixus Stahl

Positively-Charged Semi-Tunnel Is a Structural and Surface Characteristic of Polyphosphate-Binding Proteins: An In-Silico Study

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