RESUMO
Phosphorylation of histone H4 on one or both of its two histidine residues has been known to occur in liver cells for nearly 40 years and has been associated with proliferation of hepatocytes during regeneration of the liver following mechanical damage. More recently, large increases in histone H4 histidine kinase activity have been found to occur associated with proliferation and differentiation of liver progenitor cells following chemical damage that prevents hepatocyte proliferation. In addition, it has been shown this histone H4 histidine kinase activity is elevated nearly 100-fold in human foetal liver and several hundredfold in hepatocellular carcinoma tissue compared with normal adult liver. In the present paper, we review what is currently known about histone H4 histidine phosphorylation, the kinase(s) responsible and the phosphatases capable of catalysing its dephosphorylation, and briefly summarize the techniques used to detect and measure the histidine phosphorylation of histone H4 and the corresponding kinase activity.
Assuntos
Histonas/fisiologia , Neoplasias Hepáticas/enzimologia , Regeneração Hepática , Monoéster Fosfórico Hidrolases/metabolismo , Proteínas Quinases/metabolismo , Animais , Histidina/análogos & derivados , Histidina/metabolismo , Histidina Quinase , Histonas/metabolismo , Humanos , Nucleossomos/química , Fosforilação , Processamento de Proteína Pós-Traducional , Estabilidade Proteica , Estrutura Quaternária de ProteínaRESUMO
Histidine-phosphorylated proteins and the corresponding kinases are important components of bacterial and eukaryotic cell-signalling pathways, and are therefore potential drug targets. The study of these biomolecules has been hampered by the lability of the phosphoramidate functional group in the phosphohistidines and the lack of generic antibodies. Herein, the design and concise synthesis of stable triazolylphosphonate analogues of N1- and N3-phosphohistidine, and derivatives suitable for bioconjugation, are described.
Assuntos
Histidina/análogos & derivados , Organofosfonatos/síntese química , Triazóis/síntese química , Alanina/análogos & derivados , Alanina/síntese química , Alanina/química , Aminoácidos/síntese química , Catálise , Cromatografia Líquida de Alta Pressão , Química Click , Cobre/química , Fluorenos/síntese química , Haptenos/química , Histidina/síntese química , Histidina/química , Histidina/isolamento & purificação , Organofosfonatos/química , Organofosfonatos/isolamento & purificação , Estereoisomerismo , Triazóis/química , Triazóis/isolamento & purificaçãoRESUMO
The investigation of protein histidine phosphorylation has required the development of a number of methods that differ from traditional methods of phosphoprotein analysis that were developed to study phosphorylation of serine, threonine, and tyrosine, which are, unlike phosphohistidine, acid-stable. The investigation of histidine phosphorylation is further complicated by the fact that in mammalian proteins, phosphorylation appears to occur at either 1-N or 3-N positions of the imidazole ring, depending on the source of the kinase. In this review, we describe methods developed for phosphoamino acid analysis to detect phosphohistidine, including the determination of the isoform present, using chromatographic and mass spectrometric analysis of phosphoprotein hydrolysates and 1H- and 31P NMR analysis of intact phosphoproteins and phosphopeptides. We also describe methods for the assay of protein histidine kinase activity, including a quantitative assay of alkali-stable, acid-labile protein phosphorylation, and an in-gel kinase assay applied to histidine kinases. Most of the detailed descriptions of methods are as they are applied in our laboratory to the investigation of histone H4 phosphorylation and histone H4 histidine kinases, but which can be applied to the phosphorylation of any proteins and to any such histidine kinases.
Assuntos
Histidina/metabolismo , Histonas/metabolismo , Proteínas/metabolismo , Animais , Humanos , Espectrometria de Massas , Fosfoaminoácidos/química , FosforilaçãoRESUMO
Eukaryotic genomic DNA is orderly compacted to fit into the nucleus and to inhibit accessibility of specific sequences. DNA is manipulated in many different ways by bound RNA and proteins within the composite material known as chromatin. All of the biological processes that require access to genomic DNA (such as replication, recombination and transcription) therefore are dependent on the precise characteristics of chromatin in eukaryotes. This distinction underlies a fundamental property of eukaryotic versus prokaryotic gene regulation such that chromatin structure must be regulated to precisely repress or relieve repression of particular regions of the genome in an appropriate spatio-temporal manner. As well as playing a key role in structuring genomic DNA, histones are subject to site-specific modifications that can influence the organization of chromatin structure. This review examines the molecular processes regulating site-specific histone acetylation, methylation and phosphorylation with an emphasis on how these processes underpin differentiation-regulated transcription.
Assuntos
Regulação da Expressão Gênica no Desenvolvimento/genética , Histonas/metabolismo , Processamento de Proteína Pós-Traducional , HumanosRESUMO
Using peptides based on the amino acid sequences surrounding the two histidine residues in histone H4, we have investigated the kinetics of the phosphorylation and dephosphorylation reactions of their histidine residues, when reacted with potassium phosphoramidate, by (1)H NMR. We have been able to estimate rate constants for the reactions and have shown that there are differences in the kinetics between the two peptides. The kinetics of hydrolysis of phosphoramidate was measured by (31)P NMR and protein histidine phosphatase (PHP) was shown to catalyse the reaction. We have shown that the dephosphorylation of the phosphohistidine of the phosphopeptides is catalysed by PHP. In terms of substrate specificity, there is a small preference for 1-phosphohistidine compared to 3-phosphohistidine, although the rate accelerations for hydrolysis induced by the enzyme were 1100- and 33,333-fold, respectively. The kinetics of both the phosphorylation and dephosphorylation reactions depend on the amino acid sequence surrounding the histidine. PHP shows greater substrate specificity for the peptide whose sequence is similar to that around histidine 18 of histone H4. PHP was unable to catalyse the dephosphorylation of histone H4 that had been phosphorylated with a histone H4 histidine kinase.
Assuntos
Histidina/análogos & derivados , Amidas/química , Sequência de Aminoácidos , Histidina/síntese química , Histidina/genética , Histidina Quinase , Histonas/química , Cinética , Ressonância Magnética Nuclear Biomolecular , Peptídeos/metabolismo , Ácidos Fosfóricos/química , Monoéster Fosfórico Hidrolases/metabolismo , Fosforilação , Proteínas Quinases/metabolismoRESUMO
Protein histidine phosphorylation is well established as an important part of signalling systems in bacteria, fungi and plants and there is growing evidence of its role in mammalian cell biology. Compared to phosphoserine, phosphothreonine and phosphotyrosine, phosphohistidine is relatively labile, especially under the acidic conditions that were developed to analyse protein phosphorylation. In recent years, there has been an increasing impetus to develop specific methods for the analysis of histidine phosphorylation and assay of histidine kinase activity. Most recently attention has focussed on the application of mass spectrometry to this end. This review provides an overview of methods available for the detection and analysis of phosphohistidine in phosphoproteins, with particular emphasis on the application of mass spectrometric techniques.
Assuntos
Histidina/análise , Monofosfato de Adenosina/farmacologia , Animais , Sítios de Ligação , Linhagem Celular , Relação Dose-Resposta a Droga , Proteínas de Ligação ao GTP/metabolismo , Guanosina Monofosfato/farmacologia , Histidina/química , Histidina/metabolismo , Humanos , Camundongos , Núcleosídeo-Difosfato Quinase/metabolismo , Fosforilação , Ligação Proteica , Estrutura Terciária de Proteína , Ovinos , Uridina Monofosfato/farmacologiaRESUMO
Unlike other eukaryotes studied to date, yeast has two genes for pyruvate carboxylase coding for very similar, but not identical, isozymes (Pyc1 and Pyc2), both of which are located in the cytoplasm. We have found that there are marked differences in the kinetic properties of the isozymes potentially leading to differential regulation of Pyc1 and Pyc2 activity by both activators and substrates. For example, Pyc2 is only activated 3.7-fold by acetyl CoA, and 9.6-fold by NH(4)(+), whilst the figures for Pyc1 are 16 and 14.6-fold, respectively. Pyc1 and Pyc2 display different allosteric properties with respect to acetyl CoA activation and aspartate inhibition, with Pyc1 showing a higher degree of cooperativity than Pyc2, even in the absence of aspartate. We have investigated the locus of action in the amino acid sequence of the isozymes of this activator by measuring its regulation of various chimeric constructs of the two isozymes. In this way, we conclude that the main locus of action of acetyl CoA lies in the N-terminal half of the enzyme, within the biotin-carboxylation domain, between amino acids 99 and 478 of Pyc1.
Assuntos
Acetilcoenzima A/farmacologia , Piruvato Carboxilase/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Sequência de Aminoácidos , Ácido Aspártico/farmacologia , Biotina/metabolismo , Ativação Enzimática/efeitos dos fármacos , Isoenzimas/genética , Isoenzimas/metabolismo , Cinética , Dados de Sequência Molecular , Piruvato Carboxilase/genética , Compostos de Amônio Quaternário/farmacologia , Proteínas Recombinantes de Fusão/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Homologia de Sequência de AminoácidosRESUMO
Protein phosphorylation is one of the most ubiquitous and important types of post-translational modification for the regulation of cell function. The importance of two-component histidine kinases in bacteria, fungi and plants has long been recognised. In mammals, the regulatory roles of serine/threonine and tyrosine kinases have attracted most attention. However, the existence of histidine kinases in mammalian cells has been known for many years, although little is still understood about their biological roles by comparison with the hydroxyamino acid kinases. In addition, with the exception of NDP kinase, other mammalian histidine kinases remain to be identified and characterised. NDP kinase is a multifunctional enzyme that appears to act as a protein histidine kinase and as such, to regulate the activation of some G-proteins. Histone H4 histidine kinase activity has been shown to correlate with cellular proliferation and there is evidence that it is an oncodevelopmental marker in liver. This review mainly concentrates on describing recent research on these two types of histidine kinase. Developments in methods for the detection and assay of histidine kinases, including mass spectrometric methods for the detection of phosphohistidines in proteins and in-gel kinase assays for histone H4 histidine kinases, are described. Little is known about inhibitors of mammalian histidine kinases, although there is much interest in two-component histidine kinase inhibitors as potential antibiotics. The inhibition of a histone H4 histidine kinase by genistein is described and that of two-component histidine kinase inhibitors of structurally-related mammalian protein kinases. In addition, recent findings concerning mammalian protein histidine phosphatases are briefly described.
Assuntos
Proteínas Quinases/metabolismo , Animais , Inibidores Enzimáticos/metabolismo , Inibidores Enzimáticos/farmacologia , Histidina/metabolismo , Histidina Quinase , Histonas/metabolismo , Humanos , Mamíferos/metabolismo , Modelos Moleculares , Núcleosídeo-Difosfato Quinase/metabolismo , Monoéster Fosfórico Hidrolases/metabolismo , Fosforilação , Proteínas Quinases/química , Estrutura Terciária de Proteína , ProteômicaRESUMO
Protein phosphorylation is a vital process in the regulation of mammalian cell division and the protein kinases that catalyze the phosphorylation of proteins on serine, threonine and tyrosine residues have been well characterized. In contrast, little is known about the kinases involved in protein histidine phosphorylation, which have been described in various mammalian cells that are highly proliferative. Histone H4 histidine kinase (HHK) activity is highly active in regenerating rat liver. Using a novel and specific assay, we demonstrate that it is active in human fetal liver, essentially absent in adult liver and highly expressed in liver tumours. 'Normal' liver surrounding the HCC contains low to undetectable levels of HHK. In a rodent model of chronic liver injury that leads to HCC, its activity is induced. Two lines of evidence suggest that liver progenitor (oval) cells, which populate the liver at early stages following induction of liver damage are responsible for the increased activity. Purified oval cells, as well as cell lines established from primary cultures of oval cells express high levels of HHK. We propose that the pattern of expression of histone H4 histidine kinase activity justifies its classification as an oncodevelopmental marker and suggest it may be useful as a diagnostic marker for hepatocellular carcinoma as well for identifying preneoplastic lesions.
Assuntos
Hepatócitos/enzimologia , Proteínas Quinases/metabolismo , Adulto , Biomarcadores Tumorais/metabolismo , Carcinoma Hepatocelular/enzimologia , Linhagem Celular , Núcleo Celular/enzimologia , Feto , Regulação da Expressão Gênica no Desenvolvimento , Hepatectomia , Histidina Quinase , Humanos , Imuno-Histoquímica , Cinética , Fígado/embriologia , Fígado/enzimologia , Neoplasias Hepáticas/enzimologia , Fosforilação , Antígeno Nuclear de Célula em Proliferação/análise , Proteínas Quinases/genéticaRESUMO
This study aims to investigate functionally similar proteins based on their capacity to remain bound to ATP under stringent resolving conditions. Using two-dimensional gel electrophoresis and capillary liquid chromatography on-line mass spectrometry, we have identified several mammalian and E. coli proteins that appear to covalently bind ATP. To validate this approach, we obtained commercially purified forms of proteins identified from two-dimensional protein maps and tested their capacity to bind alpha 32P phosphate labeled ATP. This proteomics approach provides an initial screening method of identifying functionally similar proteins for further scrutiny by a more traditional analysis.
Assuntos
Trifosfato de Adenosina/química , Proteínas/análise , Proteínas/química , Proteômica/métodos , Animais , Cromatografia Líquida de Alta Pressão , Eletroforese em Gel Bidimensional , Proteínas de Escherichia coli/análise , Proteínas de Escherichia coli/química , Humanos , Espectrometria de Massas , Isótopos de FósforoRESUMO
The methods that detect histidine phosphorylation have largely been either laborious or difficult to apply quantitatively. The major difficulty in assessing for its presence is its alkali-stable, acid-labile nature. While an assay that detects alkali-stable phosphorylation has been developed, it does not distinguish phosphohistidine from other alkali-stable phosphoamino acids. Using this established method, we extend the assay to facilitate the specific detection of phosphohistidine. We use the acid-lability of phosphohistidine as a defining feature in our approach for its detection. In addition, reverse-phase thin-layer chromatography was utilized to conclusively demonstrate the viability of the conditions that we implement in the assay for the selective detection of phosphohistidine. In summary, this report describes a rapid filter-based kinase assay that quantitatively measures histidine kinase activity, even in the presence of tyrosine kinase activity.
Assuntos
Cromatografia em Camada Fina/métodos , Histidina/análogos & derivados , Proteínas Quinases/análise , Proteínas Fúngicas/análise , Histidina/análise , Histidina Quinase , Histonas/análise , Membranas Artificiais , Fosforilação , Proteínas Quinases/metabolismoRESUMO
The existence of protein kinases, known as histidine kinases, which phosphorylate their substrates on histidine residues has been well documented in bacteria and also in lower eukaryotes such as yeast and plants. Their biological roles in cellular signalling pathways within these organisms have also been well characterised. The evidence for the existence of such enzymes in mammalian cells is much less well established and little has been determined about their cellular functions. The aim of the current review is to present a summary of what is known about mammalian histidine kinases. In addition, by consideration of the chemistry of phosphohistidine, what is currently known of some mammalian histidine kinases and the way in which they act in bacteria and other eukaryotes, a general role for mammalian histidine kinases is proposed. A histidine kinase phosphorylates a substrate protein, by virtue of the relatively high free energy of hydrolysis of phosphohistidine the phosphate group is easily transferred to either a small molecule or another protein with which the phosphorylated substrate protein specifically interacts. This allows a signalling process to occur, which may be downregulated by the action of phosphatases. Given the known importance of protein phosphorylation to the regulation of almost all aspects of cellular function, the investigation of the largely unexplored area of histidine phosphorylation in mammalian cells is likely to provide a greater understanding of cellular action and possibly provide a new set of therapeutic drug targets.
Assuntos
Histidina/análogos & derivados , Proteínas Quinases/fisiologia , Animais , Sítios de Ligação , Dimerização , Proteínas de Ligação ao GTP/metabolismo , Histidina/química , Histidina Quinase , Humanos , Modelos Biológicos , Modelos Químicos , Fosforilação , Proteínas Quinases/química , Estrutura Terciária de Proteína , Transdução de SinaisRESUMO
The 90-kDa heat shock family (HSP90) of protein and two-component histidine kinases, although quite distinct at the primary amino acid sequence level, share a common structural ATP-binding domain known as the Bergerat fold. The Bergerat fold is important for the ATPase activity and associated chaperone function of HSP90. Two-component histidine kinases occur in bacteria, yeast, and plants but have yet to be identified in mammalian cells. The antifungal antibiotic radicicol (Monorden) has been shown to bind to the Bergerat fold of HSP90 and to inhibit its ATPase activity. The structural similarity between the Bergerat fold of HSP90 and bacterial two-component histidine kinases prompted our inquiry into whether radicicol could be a potential inhibitor of histidine kinase-like proteins. Structural homology searches suggest that the ATP-binding domains of the yeast histidine kinase Sln1 and the mammalian, branched-chain alpha-keto acid dehydrogenase kinase are very similar to that of other Bergerat fold family members. On the basis of structural homology, we tested radicicol as a potential inhibitor of Sln1 and branched-chain alpha-keto acid dehydrogenase kinase (BCKDHK) and propose a mechanism of inhibition of these kinases. Although BCKDHK has been shown to have serine autophosphorylation activity, we speculate, based on the results from this study and other supporting evidence, that BCKDHK may also have intrinsic histidine kinase activity.
Assuntos
Inibidores Enzimáticos/farmacologia , Proteínas Fúngicas/antagonistas & inibidores , Lactonas/farmacologia , Inibidores de Proteínas Quinases , Proteínas Quinases , Proteínas de Saccharomyces cerevisiae , Sequência de Aminoácidos , Antifúngicos/farmacologia , Proteínas de Choque Térmico HSP90/química , Peptídeos e Proteínas de Sinalização Intracelular , Macrolídeos , Dados de Sequência Molecular , Fosforilação/efeitos dos fármacos , Homologia de Sequência de Aminoácidos , Leveduras/efeitos dos fármacos , Leveduras/enzimologiaAssuntos
Proteínas Quinases/metabolismo , Animais , Histidina Quinase , Histonas/metabolismo , Mamíferos , FosforilaçãoRESUMO
Whereas phosphoesters of serine, threonine, and tyrosine are present in great abundance in mammalian cells, only limited information is available for other amino acids modified by a phosphate group. Phosphohistidine in proteins has been discovered in mammalian cells, but no enzyme with histidine kinase activity has been reported to date. The present study demonstrates for the first time the histidine kinase activity of a mammalian protein. Branched-chain alpha-ketoacid dehydrogenase kinase, a mitochondrial enzyme, has high sequence similarity with histidine kinases from lower organisms but has been classified as a serine/threonine kinase. Our studies indicate that in addition to a serine this enzyme also autophosphorylates a histidine residue. This finding suggests that histidine kinases are not restricted to lower organisms.