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PubMedDate not supplied

[Isolation and certain features of a polyphosphate phosphohydrolase deficient mutant of the fungus Neurospora crassa].

A polyphosphatase deficient mutant of Neurospora crassa has been isolated. The criterion for selecting the mutant was the capacity of the fungus to assimilate polyphosphates as the source of exogenous phosphorus. The mutant like the parent strain ad-6, was an adenine auxotroph but differed from the parent strain by a lower growth rate though, at the stationary stage, its biomass reached the same level as in the strain ad-6. The character of changes in the activity of polyphosphatase in the course of growth was the same in the two cultures, but the activity of the enzyme in the mutant was considerably lower at all the growth stages. The content of polyphosphate fractions with the highest molecular weight increased twofold in the mutant culture. These data suggest that there is a close metabolic and topographic correlation between polyphosphatase and the highest molecular weight fractions of polyphosphates in N. crassa.

Acid Anhydride Hydrolases↗
PubMed1984

[Gonococcal and nongonococcal urethritis in the male. Apropos of 100 cases treated with doxycycline polyphosphate].

After pointing out the epidemiological significance of sexually transmitted diseases, the authors report results in 100 male patients given doxycycline polyphosphate during 2 weeks for urethritis. Ten patients had post-gonococcal urethritis and twenty others had persistent urethritis afer a first treatment had failed. The association Chlamydia trachomatis-Staphylococcus albus was the most common bacteriologic finding. Staphylococcus aureus and Neisseria gonorrhea were demonstrated in 24 and 12 cases respectively. Ureaplasma urealyticum was found in only four instances. Clinical and bacteriological results show that doxycycline polyphosphate was effective in 92 out of 100 cases. Circumstances of the eight failures are analyzed specifically. Clinical tolerance was excellent in every case. Following confrontation with recent data from the literature, these results lead the authors to conclude that gonococcal and non-gonococcal urethritis is an indication of choice for doxycycline polyphosphate.

Adult↗
PubMed1980

Pyrimidine nucleotide pool changes during the cell cycle and quiescence. Pyrimidine excretion and metabolic isolation of the pyrimidine mononucleoside polyphosphate pool.

We have measured the pyrimidine nucleotide contents of the culture fluid, acid-soluble fraction, and acid-insoluble fraction of cultures of hamster embryo fibroblasts (third subculture) through the final two divisions of growth in culture. The cells show a growth delay between the penultimate and ultimate division periods and a concomitant biochemical synchrony of pyrimidine metabolism. The cells exhibit normal excretion of pyrimidine nucleotides beginning with the ultimate division cycle. This excretion results from the net breakdown of ribonucleic acid and a cell-regulated maximum for pyrimidine mononucleoside polyphosphate content. This upper limit for the pyrimidine nucleoside polyphosphate content is not a steady state phenomenon but rather an absence of both synthesis and utilization. The hamster embryo fibroblast exhibits a directed flow of salvage uridine for ribonucleic acid synthesis. We show that de novo synthetic uridine 5'-monophosphate also can be used for ribonucleic acid synthesis without prior entry into the cytoplasmic uridine nucleoside polyphosphate pool. During attachment and first division salvage uridine does enter the cytoplasmic nucleotide pool. The properties of the cytidine pools differ from the uridine pools in specific activity and levels of cytidine, due to turnover of the terminal C-C-A of cytoplasmic transfer ribonucleic acid and the delay in conversion of of nonradioactive de novo synthetic uridine 5'-monophosphate to cytidine 5'-triphosphate. The partial synchrony in these cultures has been used as a temporal marker of the observed events.

Animals↗
PubMed1977

[ On the absence of high-molecular polyphosphates in chloroplasts of Acetabularia mediterranea].

High-molecular polyphosphates have been identified in a crude fraction of chloroplasts of Acetabularia mediterranea. However, after a short-term treatment of the fraction with a hypotonic salt solution and centrifugation in a sucrose density gradient it was found possible to completely separate high-molecular polyphosphates from intact chloroplasts. Consequently the chloroplasts themselves contain no high-molecular polyphosphates. It is assumed that the high-molecular polysphates found in a crude fraction of chloroplasts are constitutents of the "metachromatic" granules which can be revealed in the A. mediterranea cytoplasm by cytochemical methods.

Acetabularia↗
PubMed1995

Diadenosine polyphosphate-induced increase in cytosolic free calcium in vascular smooth muscle cells.

OBJECTIVE: To evaluate the effects of two new endogenous vasoconstricting substances, diadenosine pentaphosphate (AP5A) and diadenosine hexaphosphate (AP6A) on the cytosolic free calcium concentration in vascular smooth muscle cells. METHODS: Spectrofluorophotometric measurements of cytosolic Ca2+ were conducted in monolayers of cultured rat vascular smooth muscle cells using the calcium-sensitive fluorescent dye fura-2. RESULTS: The resting Ca2+ concentration in vascular smooth muscle cells was 80 +/- 5 nmol/l (mean +/- SEM; n = 39). The addition of 10 mu mol/l AP5A or AP6A significantly increased Ca2+ in vascular smooth muscle cells to 248 +/- 55 and 358 +/- 124 nmol/l, respectively. The sustained increase in Ca2+ after administration of AP5A or AP6A was 143 +/- 40 and 148 +/- 57 nmol/l, respectively. Diadenosine polyphosphates induce a transplasmamembrane calcium influx as detected by experiments in the absence of external calcium or by using the manganese quenching technique to report unidirectional calcium fluxes. The effects of diadenosine polyphosphates were compared to those of the well known vasoconstrictor angiotensin II, which increased Ca2+ in vascular smooth muscle cells by 1053 +/- 174 nmol/l. CONCLUSIONS: Diadenosine polyphosphates increase Ca2+ in vascular smooth muscle cells, thereby regulating the contractility of vascular smooth muscle and subsequently blood pressure.

Animals↗
PubMed1978

Autoradiographic studies of fracture healing using 99Tcm-Sn-polyphosphate.

Using 99Tcm-Sn-polyphosphate, macroautoradiographs were produced of 34 standardized, medullary-nailed, 1--10-week-old tibial fractures in the rat. The radioactivity was localized in the callus and epiphyseal growth plate. On microautoradiography the 99Tcm-Sn-polyphosphate was found diffusely scattered within the mineralizing part of the callus and the epiphyseal growth plate.

Animals↗
PubMed2003

Identification and comparison of aerobic and denitrifying polyphosphate-accumulating organisms.

Two laboratory-scale sequencing batch reactors (SBRs) were operated for enhanced biological phosphorus removal (EBPR) in alternating anaerobic-aerobic or alternating anaerobic-anoxic modes, respectively. Polyphosphate-accumulating organisms (PAOs) were enriched in the anaerobic-aerobic SBR and denitrifying PAOs (DPAOs) were enriched in the anaerobic-aerobic SBR. Fluorescence in situ hybridization (FISH) demonstrated that the well-known PAO, "Candidatus Accumulibacter phosphatis" was abundant in both SBRs, and post-FISH chemical staining with 4,6-diamidino-2-phenylindol (DAPI) confirmed that they accumulated polyphosphate. When the anaerobic-anoxic SBR enriched for DPAOs was converted to anaerobic-aerobic operation, aerobic uptake of phosphorus by the resident microbial community occurred immediately. However, when the anaerobic-aerobic SBR enriched for PAOs was exposed to one cycle with anoxic rather than aerobic conditions, a 5-h lag period elapsed before phosphorus uptake proceeded. This anoxic phosphorus-uptake lag phase was not observed in the subsequent anaerobic-aerobic cycle. These results demonstrate that the PAOs that dominated the anaerobic-aerobic SBR biomass were the same organisms as the DPAOs enriched under anaerobic-anoxic conditions.

Aerobiosis↗
PubMed1994

Purification and characterization of D-myo-inositol (1,4,5)/(1,3,4,5)- polyphosphate 5-phosphatase from skeletal muscle.

In this investigation we report the presence of two forms of inositol (1,4,5)P3/(1,3,4,5)P4-polyphosphate 5-phosphatase activity (types I and II) which were observed in soluble extracts of skeletal muscle after fractionation by DEAE-Sephacel chromatography. Hydrolysis of D-myo-inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) and D-myo-inositol 1,3,4,5-tetrakisphosphate by both phosphatases was 5-phosphate-specific, Mg2+ ion-dependent and inhibited by D-2,3-bisphosphoglycerate. Soluble type I 5-phosphatase activity was purified 27,300-fold to a specific activity of 2.54 mumol of Ins(1,4,5)P3 hydrolyzed/min/mg protein after a combination of DEAE-Sephacel, Blue Sepharose, heparin-agarose and structural analogue affinity chromatography. Purified type I 5-phosphatase had an apparent mean Km of 8.9 and 1.1 microM and Vmax of 3.55 and 0.13 mumol of substrate hydrolyzed/min/mg protein for Ins(1,4,5)P3 and Ins(1,3,4,5)P4, respectively. Investigations on soluble type II 5-phosphatase after DEAE-Sephacel chromatography indicated an apparent Km of 71.4 microM Ins(1,4,5)P3 and an apparent molecular mass of 81 kDa. Soluble type I phosphatase has an apparent molecular mass of 48 kDa and an isoelectric point of 5.8. Soluble type I 5-phosphatase has kinetic constants which suggest a role in the regulation of inositol polyphosphates at physiological concentrations. These results support a role for Ins(1,4,5)P3 in the regulation of Ca2+ homeostasis in skeletal muscle.

2,3-Diphosphoglycerate↗
PubMed1993

Determination of endopolyphosphatase using polyphosphate glucokinase.

A method has been developed for determining endopolyphosphatase (polyphosphate depolymerase, EC 3.6.1.10) activity. The enzyme catalyzes the hydrolysis of inorganic polyphosphates [poly(Ps)] by cleaving internal phosphoanhydride bonds without removal of terminal phosphate residues. During the reaction, shorter poly(P) chains are formed and the molar concentration of poly(P) increases. This enzymatic activity is difficult to quantitate, because the substrates and products of the reaction are chemically identical. The commonly used viscometric method lacks sensitivity and cannot be used with shorter poly(P) substrates. The method described here overcomes these problems, and in addition is rapid, simple, and can be used for distinguishing between the endopolyphosphatase and exopolyphosphatase (EC 3.6.1.11) activities. It is based on monitoring the increase in the number of poly(P) chains generated by endopolyphosphatase. For this purpose, the method takes advantage of the specific property of poly(P) glucokinase (EC 2.7.1.63) which utilizes poly(Ps) of different sizes present in the endopolyphosphatase reaction mixture and reduces them to fairly uniform very short-chain product, poly(P)m. The concentration of poly(P)m is expressed in terms of acid-labile phosphorus and is proportional to the duration of the endopolyphosphatase reaction (i.e., the number of original poly(P) chains) and to protein concentration. The increase in the poly(P)m concentration is a relative measure of the endopolyphosphatase activity. Under certain conditions, m equals 3.5 and the activity can be expressed in standard units, since the exact number of poly(P) chains formed by endopolyphosphatase can be calculated from the increase in molar concentration of poly(P)3.5. Accuracy and advantages of the assay are discussed.

Acid Anhydride Hydrolases↗
PubMed1994

Kinetic analysis of novel inhibitors of inositol polyphosphate metabolism.

The ability of the novel D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P 3] analogues, L-chiro-inositol 1,4,6-trisphosphate [L-chr Ins(1,4,6)P3] and the corresponding trisphosphorothioate compound [L-chr Ins(1,4,6)PS3] to inhibit soluble inositol (1,4,5)P3/(1,3,4,5)P4-polyphosphate 5-phosphatase, potently and selectively, has been investigated. L-chr Ins(1,4,6)P3 competitively inhibited 5-phosphate specific dephosphorylation of Ins(1,4,5)P3 and inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4] with apparent Ki values of 6.35 and 1.76 microM, respectively. L-chr Ins(1,4,6)PS3 competitively inhibited hydrolysis of Ins(1,4,5)P3 and noncompetitively inhibited dephosphorylation of Ins(1,3,4,5)P4 with apparent Ki values of 0.67 and 0.44 microM, respectively. L-chr Ins(1,4,6)PS3 did not affect Ins(1,4,5)P3 3-kinase activity. In the present investigation L-chr Ins(1,4,6)P3 and L-chr Ins(1,4,6)PS3 have been shown to be the most potent and selective inhibitors of inositol polyphosphate metabolism yet described.

Animals↗
PubMed1999

Involvement of Spt7p in vacuolar polyphosphate level of Saccharomyces cerevisiae.

Saccharomyces cerevisiae became less sensitive to nickel by a defect of the SPT7 gene encoding a transcription factor. Initial rate of nickel uptake by whole cells of a SPT7-negative mutant FY963 was nearly equal to that of the parent strain FY61, and FY963 accumulated nickel about 1.7-fold of the value of FY61 when cultured in medium containing 0.1 mM NiCl2; most of which was sequestered into vacuoles. The pH gradient-driven nickel uptake by vacuolar membrane vesicles was not altered in FY963, but the amount of polyphosphate in vacuoles was highly elevated. Involvement of Spt7p in nickel detoxification through regulation of vacuolar polyphosphate level in S. cerevisiae was discussed.

Biological Transport↗
PubMed1999

Pharbin, a novel inositol polyphosphate 5-phosphatase, induces dendritic appearances in fibroblasts.

We have cloned a cDNA encoding a novel protein pharbin with a homology to inositol polyphosphate 5-phosphatases. Pharbin contains relatively well-conserved catalytic motifs for 5-phosphatase, a proline-rich sequence corresponding to the SH3-binding motif, and a sequence consistent with the CaaX motif at the C-terminus. COS-7 cells transfected with pharbin exhibited elevated hydrolytic activity on the 5-phosphate group of inositol 1,4,5-trisphosphate, inositol 1,3,4,5-tetrakisphosphate, and phosphatidylinositol 4, 5-bisphosphate. Thus, pharbin indeed serves as an inositol polyphosphate 5-phosphatase. When pharbin was transfected to C3H/10T1/2 fibroblasts, it was located to the plasma membrane-associated structures including membrane ruffles. The cells were converted to dendritic forms within 24 h. The protein with deleted or point-mutated CaaX motif hardly induced the dendritic forms but remained associated with the membranes. These results imply that the CaaX motif is required for the morphological alteration but that some other structural element is likely to also be responsible for the membrane localization.

Amino Acid Sequence↗
PubMed2000

The effect of monovalent ions on polyphosphate binding to Escherichia coli exopolyphosphatase.

The thermodynamic driving force for the interaction of Escherichia coli exopolyphosphatase (PPX) with polyphosphate was investigated by varying salt choice and concentration. This interaction was found to be cation concentration independent but weakly dependent on the concentration of certain anions. Both of these traits are very uncommon for nonspecific protein-polyelectrolyte interactions. Interpretation of these results based on theory indicated that binding was not entropy driven due to release of polyelectrolyte-condensed counterions, as is the case for nearly all protein-polyelectrolyte interactions. The thermodynamics of the PPX-polyphosphate interaction showed similarity only to the interaction of polynucleotides with single stranded binding proteins.

Acid Anhydride Hydrolases↗
PubMed1999

Dispersed polyphosphate in fungal vacuoles in Eucalyptus pilularis/Pisolithus tinctorius ectomycorrhizas.

Ectomycorrhizas produced between Pisolithus tinctorius and Eucalyptus pilularis under axenic conditions were rapidly frozen, freeze-substituted in tetrahydrofuran and embedded anhydrously, and dry-sectioned for X-ray microanalysis. The vacuoles of the sheath and Hartig net hyphae were rich in phosphorus and potassium. They also contained sulfur and variable amounts of chlorine. In anhydrously processed freeze-substituted mycorrhizas, dispersed electron-opaque material filled the fungal vacuoles. X-ray maps indicated that P was distributed evenly throughout the entire vacuole profile and was not concentrated in spherical bodies or subregions of the vacuole. There were no electron-opaque granules surrounded by electron-lucent areas, such as are commonly seen in chemically fixed material. The fungal vacuoles were also rich in K, which similarly gave a signal from the entire vacuolar profile. Such P-rich vacuoles occurred in both the mycorrhizal sheath and Hartig net hyphae. Stained sections of ether-acrolein freeze-substituted mycorrhizas also showed only dispersed material in the fungal vacuoles as, in most cases, did acetone-osmium freeze-substituted material. Precipitation of metachromatic granules by ethanol suggested that large amounts of polyphosphate are stored in these regions under the conditions of our experiments, as well as in the tips of actively growing hyphae of the same fungus. The higher plant vacuoles of ectomycorrhizas gave a much lower signal for K, and P was barely detectable. Much more K was located in the vacuoles of the root exodermal cells than in epidermal cells. The analysis of element distribution between the vacuole and cytoplasm in root cells agrees well with that found for other plant species using other techniques. We conclude that polyphosphate is indeed present in the vacuoles of the fungal cells of these ectomycorrhizas, but that in vivo it is in a dispersed form, not in granules.

Basidiomycota↗
PubMed1993

Purification of polyphosphate and ATP glucose phosphotransferase from Mycobacterium tuberculosis H37Ra: evidence that poly(P) and ATP glucokinase activities are catalyzed by the same enzyme.

Polyphosphate [poly(P)n]:D-(+)-glucose-6-phosphotransferase (EC 2.7.1.63) from Mycobacterium tuberculosis H37Ra was purified to homogeneity using an improved method which yielded a 634-fold purification with higher recovery. The purified enzyme migrated as a single band with M(r) 33 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The native enzyme was shown to be a dimer by gel filtration using high-performance liquid chromatography (HPLC). The purified enzyme fractionated as a single peak on a C8 reverse-phase HPLC column and was found to display both polyphosphate- and ATP-dependent glucokinase activities. Further evidence that a single protein was responsible for both activities was shown by nondenaturing PAGE, in which the two activities (as determined by an activity stain in dual experiments) were found to comigrate. The C-terminal analysis yielded a single sequence while the N-terminus which was blocked also yielded a single sequence after deblocking. The two activities were found to have the same temperature optimum of 50 degrees C. The pH optima were 9.5 and 8.6-9.5 with poly(P)32 and ATP as the phosphoryl donors, respectively. The apparent Km for poly(P)32 was 18.4 microM while the Km for ATP was 1.46 mM. In addition, the nucleotide analogue, Reactive Blue 4, was found to be a competitive inhibitor with ATP in the ATP-dependent glucokinase reaction, while it displayed noncompetitive inhibition patterns with poly(P) in the poly(P)-dependent glucokinase reaction. It is concluded that the poly(P) and ATP glucokinase activities are catalyzed by the same enzyme but that the two substrates may have different binding sites.

Amino Acid Sequence↗
PubMed1984

Studies of phosphorus metabolism by isolated nuclei. XII. Some fundamental properties of the incorporation of 32Pi into polyphosphate by rat liver nuclei.

Rat liver nuclei incubated in vitro catalyze a sustained incorporation of 32Pi into polyphosphate. A preliminary estimate indicates a minimal rate of 10 moles of Pi incorporation into polyphosphates/h/mg protein. Polyphosphate is the predominant acid-insoluble product of nuclear phosphorylation; its formation is dependent on the presence of a divalent cation and is catalyzed by a system or systems as yet uncharacterized.

Animals↗
PubMed2006

Engineering expression of bacterial polyphosphate kinase in tobacco for mercury remediation.

To develop the potential of plants to sequester and accumulate mercurials from the contaminated sites, we engineered a tobacco (Nicotiana tabacum) plant to express a bacterial ppk gene, encoding polyphosphate kinase (PPK), under control of a plant promoter. The designated plant expression plasmid pPKT116 that contains the entire coding region of ppk was used for Agrobacterium-mediated gene transfer into tobacco plants. A large number of independent transgenic tobacco plants were obtained, in some of which the ppk gene was stably integrated in the plant genome and substantially translated to the expected PPK protein in the transgenic tobacco. The presence of Hg2+ did not cause considerable morphological abnormalities in the transgenic tobacco, which grew, flowered, and set seed similarly to the wild-type tobacco on the medium containing normally toxic levels of Hg2+. The ppk-transgenic tobacco showed more resistance to Hg2+ and accumulated more mercury than its wild-type progenitors. These results suggest that ppk-specified polyphosphate has abilities to reduce mercury toxicity, probably via chelation mechanism, and also to accumulate mercury in the transgenic tobacco. Based on the results obtained in the present study, the expression of ppk gene in transgenic tobacco plants might provide a means for phytoremediation of mercury pollution.

DNA, Plant↗
PubMed1984

Evidence for polyphosphate in phosphorylated nonhistone nuclear proteins.

Structural studies of eucaryotic nuclear proteins have revealed the presence of bound polymeric phosphates. 32P-labeled and nonlabeled nonhistone nuclear proteins (NHPs) were isolated from rat liver nuclei and subjected to various controlled hydrolytic conditions. The analysis of protease-trypsin limit peptides revealed the presence of six phosphorylated, homogeneous fragments with phosphate/amino acid molar ratios greater than unity, ranging from 1.3 to 79. Alkaline beta elimination of phosphoester bonds released polymeric phosphates with chain lengths from 2 to over 200, as determined by using two-dimensional chromatographic analysis. The identity of these labeled polymeric phosphates was established to be polyphosphate by a number of criteria, including chromatographic mobility, gravimetric precipitation to constant specific activity, generation of orthophosphate on hydrolysis, and the determination of the delta H of hydrolysis of phosphoanhydride bonds. The evidence suggests that, in addition to the phosphomonoesters of serine and threonine, multiple phosphoanhydride linkages can result in the formation of polyphosphorylated NHPs. Previous investigators have demonstrated that exogenous, free polyphosphate causes destabilization of chromatin and enhancement of transcription in vitro. Although the function of the polyphosphorylated NHPs is currently unknown, such findings have possible functional implications with regard to the postulated role of NHPs as positive modifiers of gene expression.

Amino Acids↗