多聚磷和聚磷酶研究进展

多聚磷在生物体内广泛存在,并且发挥重要作用。生物体内的多聚磷是由聚磷酶催化合成的。概述了多聚磷的生物学功能,聚磷酶的功能及多聚磷和聚磷酶的应用。     

Polyphosphate in bone

Human bone-forming osteoblasts are an excellent model to investigate the multiple functions of inorganic polyphosphates (polyP) for the following reasons: 1) they contain relatively high amounts of polyP and polyP-dependent enzymes; 2) they allow the study of both general and specific functions of these polymers, and 3) medically relevant results can be expected from these studies.     

Inorganic Polyphosphate and Cancer

This review presents data on the relationship between inorganic polyphosphate metabolism and carcinogenesis including participation of polyphosphates in the regulation of activity of mTOR and other proteins involved in carcinogenesis, the role of h-prune protein (human polyphosphatase) in cell migration and metastasis formation, the prospects for using polyphosphates and inhibitors of polyphosphate metabolism enzymes as agents for controlling cell proliferation and migration.     

Polyphosphate synthesis in yeast

Polyphosphate synthesis was studied in phosphate-starved cells of Saccharomyces cerevisiae and Kluyveromyces marxianus. Incubation of these yeasts for a short time with phosphate and either glucose or ethanol resulted in the formation of polyphosphate with a short chain length. With increasing incubation times, polyphosphates with longer chain lengths were formed. Polyphosphates were synthesized faster during incubation with glucose than with ethanol. Antimycin did not affect the glucose-induced polyphosphate synthesis in either yeast. Using ethanol as an energy source, antimycin A treatment blocked both polyphosphate synthesis and accumulation of orthophosphate in the yeast S. cerevisiae. However, in K. marxianus, polyphosphate synthesis and orthophosphate accumulation proceeded normally in antimycin-treated cells, suggesting that endogenous reserves were used as energy source. This was confirmed in experiments, conducted in the absence of an exogenous energy source.     

Methods for Detection and Quantification of Polyphosphate and Polyphosphate Accumulating Microorganisms in Aquatic Sediments

It has been speculated that the microbial P pool is highly variable in the uppermost layer of various aquatic sediments, especially when an excessive P accumulation in form of polyphosphate (Poly‐P) occurs. Poly‐P storage is a universal feature of many different organisms and has been technically optimised in wastewater treatment plants (WWTP) with enhanced biological phosphorus removal (EBPR). In the recent past, new insights into mechanisms of P elimination in WWTP almost exclusively depended on the development and application of novel methods like ³¹P‐NMR spectroscopy and molecular methods for identifying Poly‐P accumulating microorganisms (PAO). The aim of the present review is to compile current methods potentially available for detection and quantification of Poly‐P in sediments and to complement it with yet unpublished results to validate their application in natural sediments. The most powerful tool for reliable Poly‐P quantification in sediments is the liquid ³¹P‐NMR technique which has been successfully used for Poly‐P measurements in a variety of aquatic sediments. But the microorganisms as well as mechanisms involved in Poly‐P storage and cycling are largely unknown. Therefore, we also intend to stimulate future studies focusing on these encouraging topics in sediment research via the implementation of novel methods. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Polyphosphate Is a Primordial Chaperone

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Inorganic Polyphosphate Modulates TRPM8 Channels

Polyphosphate (polyP) is an inorganic polymer built of tens to hundreds of phosphates, linked by high-energy phosphoanhydride bonds. PolyP forms complexes and modulates activities of many proteins including ion channels. Here we investigated the role of polyP in the function of the transient receptor potential melastatin 8 (TRPM8) channel. Using whole-cell patch-clamp and fluorescent calcium measurements we demonstrate that enzymatic breakdown of polyP by exopolyphosphatase (scPPX1) inhibits channel activity in human embryonic kidney and F-11 neuronal cells expressing TRPM8. We demonstrate that the TRPM8 channel protein is associated with polyP. Furthermore, addition of scPPX1 altered the voltage-dependence and blocked the activity of the purified TRPM8 channels reconstituted into planar lipid bilayers, where the activity of the channel was initiated by cold and menthol in the presence of phosphatidylinositol 4,5-biphosphate (PtdIns(4,5)P₂). The biochemical analysis of the TRPM8 protein also uncovered the presence of poly-(R)-3-hydroxybutyrate (PHB), which is frequently associated with polyP. We conclude that the TRPM8 protein forms a stable complex with polyP and its presence is essential for normal channel activity.     

Polyphosphate and stress response in mycobacteria

Polyphosphate (poly P) is present in every living cell. Long considered a 'molecular fossil', its role in cell physiology has been neglected. However, in the last few years it has become clear that poly P plays a role in multiple physiological functions, the best characterized of which is rpoS and recA induction during the Escherichia coli stringent response. Sureka et al. in this issue of Molecular Microbiology investigate the role of poly P in mycobacterial stress response and describe its participation in a novel regulatory pathway involving the two-component system MprAB, the alternative sigma factor sigma(E) and Rel, the enzyme responsible for (p)ppGpp metabolism in mycobacteria.     

Polyphosphate production by strains of Acinetobacter

Of four strains of Acinetobacter isolated from a pilot plant exhibiting enhanced biological phosphate removal from sewage, two strains (RA3116 and RA3117) accumulated more than 10 times the amount of polyphosphate accumulated by the other two strains (RA3114 and RA3123). Variants isolated from RA3116 and RA3117 showed polyphosphate levels similar to RA3114 and RA3123. No correlation was found between the polyphosphate content of the strains and levels of several enzymes that have been implicated in polyphosphate formation.     

Structures Containing Polyphosphate in Micrococcus lysodeikticus

Granular structures containing inorganic polyphosphate were found in Micrococcus lysodeikticus. These structures were isolated by fractionation of the bacterial extract obtained by lysing the organisms with lysozyme. The composition of the fraction which was enriched with these structures was found to be: protein, 24%; lipids, 30%; and polyphosphate, 27%. This fraction also contained small amounts of ribonucleic acids, carbohydrate, and polyvalent cations. The effect of different reagents and enzymes on the integrity of the granules was examined. It was noticed that they accumulate in the bacteria during the logarithmic phase of growth but disappear gradually during the stationary phase.     

Agonist-Stimulated Inositol Polyphosphate Formation in Cerebellum

The accumulation of inositol polyphosphates in the cerebellum in response to agonists has not been demonstrated. Guinea pig cerebellar slices prelabeled with [3H]inositol showed the following increases in response to 1 mM serotonin: At 15 s, there was a peak in 3H label in the second messenger inositol 1,4,5-trisphosphate [Ins(1,4,5)P3], decreasing to a lower level in about 1 min. The level of 3H label in the putative second-messenger inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4] increased rapidly up to 60 s and increased slowly thereafter. The accumulation of 3H label in various inositol phosphate isomers at 10 min, when steady state was obtained, showed the following increases due to serotonin: inositol 1,3,4-trisphosphate [Ins(1,3,4)P3], eight-fold; Ins(1,3,4,5)P4, 6.4-fold; Ins(1,4,5)P3, 75%; inositol 1,4-bisphosphate [Ins(1,4)P2], 0%; inositol 3,4-bisphosphate, 100%; inositol 1-phosphate/inositol 3-phosphate, 30%; and inositol 4-phosphate, 40%. [3H]Inositol 1,3-bisphosphate was not detected in controls, but it accounted for 7.2% of the total inositol bisphosphates formed in the serotonin-stimulated samples. The fact that serotonin did not increase the formation of Ins(1,4)P2 could be due to the fact that Ins(1,4)P2 is rapidly degraded or that Ins(1,4,5)P3 is metabolized primarily by Ins(1,4,5)P3-3'kinase to form Ins(1,3,4,5)P4. In the presence of pargyline (10 microM), [3H]Ins(1,3,4,5)P4 and [3H]Ins(1,3,4)P3 levels were increased, even at 1 microM serotonin. Ketanserin (7 microM) completely inhibited the serotonin effect, indicating stimulation of serotonin2 receptors. Quisqualic acid (100 microM) also increased the levels of [3H]Ins(1,4,5)P3, [3H]Ins(1,3,4,5)P4, and [3H]Ins(1,3,4)P3, but the profile of these increases was different.(ABSTRACT TRUNCATED AT 250 WORDS)     

Properties of Polyphosphate Glucokinase in Achromobacter butyri

The activities of polyphosphate glucokinase which synthesizes glucose-6-phosphate from glucose and metaphosphate were found in some microorganisms. This enzyme occurred most abundantly in Micrococcus and Achromobacter species and less in Brevibacterium, Aerobacter and Alcaligenes species. The distribution pattern of this enzyme was closely similar to that of polyphosphate NAD kinase. Polyphosphate glucokinase in A. butyri was different from ATP-dependent glucokinase in some enzymatic properties. The potent phosphoryl donor for this enzyme was metaphosphate, and other chain or ring phosphate polymers were not utilized by this enzyme.     

拟南芥中myo-肌醇-多磷酸合成与代谢及其信号

在酵母、真菌、动物和植物等真核生物中, 以myo-肌醇为基石通过不同位点的磷酸化形成各种myo-肌醇-多磷酸及其衍生物。过去10年的研究发现这些肌醇多磷酸参与了膜脂定向转运、蛋白结构稳定、离子通道调控、RNA转运以及DNA修复和染色质重塑等细胞生物学的基本进程。近些年在模式植物拟南芥(Arabidopsis thaliana)的研究中, 许多调控植物生长发育和环境胁迫应答的重要基因被发现, 并证实这些基因参与myo-肌醇-多磷酸的合成与代谢。该文概述了拟南芥中myo-肌醇-多磷酸合成与代谢的基因调控机理, 综述了不同肌醇多磷酸作为信号分子的功能, 提出肌醇多磷酸如同一类信息代码传递着植物细胞有序进程的基本指令。     

Polyphosphate kinase activity in yeast vacuoles]

The enzyme polyphosphate kinase (ATP: Polyphosphate phosphotransferase EC 2.7.4.1) relating to the class of transferases was detected in the vacuoles of Saccharomyces carlsbergensis yeast. The direct ATP: Polyphosphate phosphotransferase reaction resulting in the synthesis of polyphosphates from ATP was shown to occur mainly in vacuoles. The localization of the reverse polyphosphate: ADP phosphatransferase reaction was not established in any of the subcellular yeast fractions studied. The activity of the direct reaction in the yeast protoplasts makes up about 1% of the reverse one, but in vacuoles it is significantly higher and makes up to 19%. Under activation of biochemical processes involved in the production of cell wall components by protoplasts, vacuolar polyphosphates work mainly in the direction of ATP synthesis at the expense of polyphosphates accumulated in vacuoles.     

微生物细胞中的聚磷酸及研究方法

聚磷酸是一种由多个磷酸基通过高能磷酸键连接而成的线性聚合分子,存在于所有生物体中,具有重要的生理功能。由于缺少特异的研究方法,为聚磷酸代谢和生理功能的研究带来很大的困难。对迄今为止的相关文献进行了综述,主要介绍微生物细胞内的聚磷酸,其中包括参与生物合成和降解过程的几种重要的酶、聚磷酸生物学功能、胁迫作用下调节聚磷酸以及聚磷酸对基因表达的调控模型和工业应用;还从分离技术、定位技术、定量分析技术3个方面重点概述了聚磷酸的研究方法。