Activity-based probes as a tool for functional proteomic analysis of proteases

Traditional proteomics methodology allows global analysis of protein abundance but does not provide information on the regulation of protein activity. Proteases, in particular, are known for their multilayered post-translational activity regulation that can lead to a significant difference between protease abundance levels and their enzyme activity. To address these issues, the field of activity-based proteomics has been established in order to characterize protein activity and monitor the functional regulation of enzymes in complex proteomes. In this review, we present structural features of activity-based probes for proteases and discuss their applications in proteomic profiling of various catalytic classes of proteases.     

Putting proteomics on target: activity-based profiling of ubiquitin and ubiquitin-like processing enzymes

Modification of proteins with ubiquitin (Ub) and Ub-like modifiers (Ubls) plays a fundamental role in cell biology. As a consequence, proteomics-based efforts were developed to characterize proteins that are modified by Ub or Ubls. A more focused functional proteomics strategy relies on active-site probes based on the Ub/Ubl scaffold, which specifically targets Ub/Ubl-processing enzymes. Activity-based profiling with such tools led to the identification of novel gene products with Ub/Ubl-processing activity and uncovered novel control mechanisms regulating their activity. This review discusses recent advances in chemistry-based functional proteomics applications, and how this information can provide a framework for drug development against Ub/Ubl-processing enzymes.     

蛋白质组学研究中的双向电泳技术

蛋白质组学研究已经成为后基因组时代的研究热点,其两大支柱是双向凝胶电泳技术和生物质谱技术。尽管双向电泳技术近几年已经取得了突破性进展,是当前蛋白质分离的最常用技术,但其本身还有一些难以克服的问题。随着质谱技术的快速发展,双向电泳逐渐成为蛋白质组学研究的瓶颈。本综述双向电泳主要技术步骤的现状、存在问题及其改进方向。     

Analysis of protein expression in cell microarrays: a tool for antibody-based proteomics.

Tissue microarray (TMA) technology provides a possibility to explore protein expression patterns in a multitude of normal and disease tissues in a high-throughput setting. Although TMAs have been used for analysis of tissue samples, robust methods for studying in vitro cultured cell lines and cell aspirates in a TMA format have been lacking. We have adopted a technique to homogeneously distribute cells in an agarose gel matrix, creating an artificial tissue. This enables simultaneous profiling of protein expression in suspension- and adherent-grown cell samples assembled in a microarray. In addition, the present study provides an optimized strategy for the basic laboratory steps to efficiently produce TMAs. Presented modifications resulted in an improved quality of specimens and a higher section yield compared with standard TMA production protocols. Sections from the generated cell TMAs were tested for immunohistochemical staining properties using 20 well-characterized antibodies. Comparison of immunoreactivity in cultured dispersed cells and corresponding cells in tissue samples showed congruent results for all tested antibodies. We conclude that a modified TMA technique, including cell samples, provides a valuable tool for high-throughput analysis of protein expression, and that this technique can be used for global approaches to explore the human proteome.     

Activity-based proteomics: enzymatic activity profiling in complex proteomes

Summary. In the postgenomic era new technologies are emerging for global analysis of protein function. The introduction of active site-directed chemical probes for enzymatic activity profiling in complex mixtures, known as activity-based proteomics has greatly accelerated functional annotation of proteins. Here we review probe design for different enzyme classes including serine hydrolases, cysteine proteases, tyrosine phosphatases, glycosidases, and others. These probes are usually detected by their fluorescent, radioactive or affinity tags and their protein targets are analyzed using established proteomics techniques. Recent developments, such as the design of probes for in vivo analysis of proteomes, as well as microarray technologies for higher throughput screenings of protein specificity and the application of activity-based probes for drug screening are highlighted. We focus on biological applications of activity-based probes for target and inhibitor discovery and discuss challenges for future development of this field.     

蛋白质组研究中分离新技术与新方法

对于蛋白质组的研究离不开分析技术的支撑。由于样品及其基质的复杂性,为了实现蛋白质的高通量、高灵敏度、快速分析鉴定,必须发展与之匹配的新技术与新方法。多维高效液相色谱/毛细管电泳技术,部分弥补了传统2D PAGE的不足,近年来,在蛋白质分离鉴定方面取得了最令人瞩目的成绩。本文分别从多维液相色谱分离技术、多维毛细管电泳蛋白质分离平台、微柱液相-毛细管电泳联用技术、极端pH蛋白质的分离分析和蛋白质的在线富集技术等方面对蛋白质组学研究中在新技术与新方法方面近期取得的成果加以系统阐述。     

A novel strategy for quantitative proteomics using isotope-coded protein labels

Stable isotope labelling in combination with mass spectrometry has emerged as a powerful tool to identify and relatively quantify thousands of proteins within complex protein mixtures. Here we describe a novel method, termed isotope-coded protein label (ICPL), which is capable of high-throughput quantitative proteome profiling on a global scale. Since ICPL is based on stable isotope tagging at the frequent free amino groups of isolated intact proteins, it is applicable to any protein sample, including extracts from tissues or body fluids, and compatible to all separation methods currently employed in proteome studies. The method showed highly accurate and reproducible quantification of proteins and yielded high sequence coverage, indispensable for the detection of post-translational modifications and protein isoforms. The efficiency (e.g. accuracy, dynamic range, sensitivity, speed) of the approach is demonstrated by comparative analysis of two differentially spiked proteomes.     

Two-dimensional gel electrophoresis in bacterial proteomics

Two-dimensional gel electrophoresis (2-DE) is a gel-based technique widely used for analyzing the protein composition of biological samples.It is capable of resolving complex mixtures containing more than a thousand protein components into individual protein spots through the coupling of two orthogonal biophysical separation techniques:isoelectric focusing (first dimension) and polyacrylamide gel electrophoresis (second dimension).2-DE is ideally suited for analyzing the entire expressed protein complement of a bacterial cell:its proteome.Its relative simplicity and good reproducibility have led to 2-DE being widely used for exploring proteomics within a wide range of environmentsl and medically-relevant bacteria.Here we give a broad overview of the basic principles and historical development of gel-based proteomics,and how this powerful approach can be applied for studying bacterial biology and physiology.We highlight specific 2-DE applications that can be used to analyze when,where and how much proteins are expressed.The links between proteomics,genomics and mass spectrometry are discussed.We explore how proteomics involving tandem mass spectrometry can be used to analyze (post-translational) protein modifications or to identify proteins of unknown origin by de novo peptide sequencing.The use of proteome fractionation techniques and non-gel-based proteemic approaches are also discussed.We highlight how the analysis of protsins secreted by bacterial cells (secretomes or exoproteomes) can be used to study infection processes or the immune response.This review is aimed at non-specialists who wish to gain a concise,comprehensive and contemporary overview of the nature and applications of bacterial proteomics.     

The methods of quantitative proteomics

In modern science proteomic analysis is inseparable from other fields of systemic biology. Possessing huge resources quantitative proteomics operates colossal information on molecular mechanisms of life. Advances in proteomics help researchers to solve complex problems of cell signaling, posttranslational modification, structure and funciotnal homology of proteins, molecular diagnostics etc. More than 40 various methods have been developed in proteomics for quantitative analysis of proteins. Although each method is unique and has certain advantages and disadvantages all these use various isotope labels (tags). In this review we will consider the most popular and effective methods employing both chemical modifications of proteins and also metabolic and enzymatic methods of isotope labeling.     

Activity-based probes as a tool for functional proteomic analysis of proteases

Traditional proteomics methodology allows global analysis of protein abundance but does not provide information on the regulation of protein activity. Proteases, in particular, are known for their multilayered post-translational activity regulation that can lead to a significant difference between protease abundance levels and their enzyme activity. To address these issues, the field of activity-based proteomics has been established in order to characterize protein activity and monitor the functional regulation of enzymes in complex proteomes. In this review, we present structural features of activity-based probes for proteases and discuss their applications in proteomic profiling of various catalytic classes of proteases.     

Mass spectrometry technologies for proteomics.

In the late 1980s, the advent of soft ionization techniques capable of generating stable gas phase ions from thermally unstable biomolecules, namely matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI), laid the way for the development of a set of powerful alternatives to the traditional Edman chemistry for the structural characterization of peptides and proteins. The rapid protein identification capabilities that, coupled with two-dimensional gel electrophoresis, provided insights into all sorts of biological systems since the dawn of proteomics and have been exploited in the last few years for the development of more powerful and automatable gel-free strategies, mainly based on multidimensional chromatographic separations of peptides from proteolytic digests. In parallel to the evolution of ion sources, mass analysers and scan modes, the invention of new elegant biochemical strategies to fractionate or simplify highly complex mixtures, or to introduce isotopic labels in peptides in a variety of ways now makes also possible large-scale, high-coverage quantitative studies in a wide dynamic range. In this review, we provide the fundamental concepts of mass spectrometry (MS) and describe the technological progress of MS-based proteomics since its earliest days. Representative literature examples of their true power, either when employed as exploratory or as targeted techniques, is provided as well.     

蛋白质组学研究中的对角线电泳

经典的蛋白质组学研究方法包括IEF/SDS-PAGE双向电泳和质谱技术的联用,但由于IEF的一些不足,限制了其应用范围。对角线电泳是蛋白质组学研究中的一项特殊分离技术,由于其原理与IEF/SDS-PAGE不同,正逐渐成为蛋白质组学中电泳分离技术的重要补充,特别是在膜蛋白和蛋白质相互关系的研究中将起到重要作用。本文综述了对角线双向电泳技术的特点、发展和在蛋白质组学研究中的最新进展,比较了双向电泳和对角线电泳的优缺点,展望了对角线电泳在蛋白质组学研究中的应用前景。     

Recent advances in quantitative and chemical proteomics for autophagy studies

Macroautophagy/autophagy is an evolutionarily well-conserved cellular degradative process with important biological functions that is closely implicated in health and disease. In recent years, quantitative mass spectrometry-based proteomics and chemical proteomics have emerged as important tools for the study of autophagy, through large-scale unbiased analysis of the proteome or through highly specific and accurate analysis of individual proteins of interest. At present, a variety of approaches have been successfully applied, including (i) expression and interaction proteomics for the study of protein post-translational modifications, (ii) investigating spatio-temporal dynamics of protein synthesis and degradation, and (iii) direct determination of protein activity and profiling molecular targets in the autophagic process. In this review, we attempted to provide an overview of principles and techniques relevant to the application of quantitative and chemical proteomics methods to autophagy, and outline the current landscape as well as future outlook of these methods in autophagy research.     

癌症差异蛋白质组学研究中样品分离和鉴定分析技术

随着人类基因组测序的完成,癌症研究的重点从基因组学转移到蛋白质组学研究中。癌症研究中的差异蛋白质组学技术也飞速发展,包括癌症样品制备、分离,蛋白质鉴定分析、蛋白质组定量研究和翻译后修饰研究等。这些技术极大地推动了与癌症相关的差异蛋白质组学研究,使蛋白质组学在癌症早期诊断、治疗,监测以及发现新药物治疗靶标方面发挥更大的作用。本文主要综述了近年来癌症差异蛋白质组学研究中样品分离和鉴定分析技术。     

从基因组学到功能蛋白质组学的研究

人类基因组草图绘制的完成,标志着生命科学已实质性地跨入了后基因组时代,研究重心已从揭示生命的所有遗传信息转移到在分子整体水平对功能的研究[1]。这种转向表明目前已进入功能基因组学(functional genom ics)以及随之产生的功能蛋白质组学(functional proteomics)等新学科领域的研究。     

Understanding signal transduction through functional proteomics

The study of signal transduction provides fundamental information regarding the regulation of all biologic processes that support the normal function of life. Functional proteomics, a rapidly emerging discipline that aims to understand the expression, function and regulation of the entire set of proteins in a given cell type, tissue or organism, offers unprecedented opportunity for signal transduction research in terms of understanding cellular behavior and regulation at the systems level. Indeed, swift progress in the area of proteomics has demonstrated the major impact of proteomic approaches on signal transduction and biomedical research. In this review, recent and innovative applications of functional proteomics in determining changes in protein contents, modifications, activities and interactions underpinning signaling transduction pathways are discussed.     

SPR技术与功能基因组和蛋白质组研究

表面等离子体共振(surface plasmon resonance,SPR)依据光学—介质相互作用原理建立,属于实时和非标记的测试方法。SPR方法在研究分子间相互作用方面具有其独特的优势,其非标记和实时检测以及可以进行动力学分析的特点,给研究生物大分子的相互作用提供了诱人的解决方案。近来,随着SPR成像技术和SPR芯片制备技术的进展,将为功能基因组学和蛋白质组学研究提供重要的新的技术平台。     

Towards functional proteomics of membrane protein complexes: analysis of thylakoid membranes from Chlamydomonas reinhardtii

Functional proteomics of membrane proteins is an important tool for the understanding of protein networks in biological membranes but structural studies on this part of the proteome are limited. In this study we undertook such an approach to analyse photosynthetic thylakoid membranes isolated from wild-type and mutant strains of Chlamydomonas reinhardtii. Thylakoid membrane proteins were separated by high-resolution two-dimensional gel electrophoresis (2-DE) and analysed by immuno-blotting and mass spectrometry for the presence of membrane-spanning proteins. Our data show that light-harvesting complex proteins (LHCP), that cross the membrane with three transmembrane domains, can be separated using this method. We have identified more than 30 different LHCP spots on our gels. Mass spectrometric analysis of 2-DE separated Lhcb1 indicates that this major LHCII protein can associate with the thylakoid membrane with part of its putative transit sequence. Separation of isolated photosystem I (PSI) complexes by 2-DE revealed the presence of 18 LHCI protein spots. The use of two peptide-specific antibodies directed against LHCI subunits supports the interpretation that some of these spots represent products arising from differential processing and post-translational modifications. In addition our data indicate that the reaction centre subunit of PSI, PsaA, that possesses 11 transmembrane domains, can be separated by 2-DE. Comparison between 2-DE maps from thylakoid membrane proteins isolated from a PSI-deficient (Deltaycf4) and a crd1 mutant, which is conditionally reduced in PSI and LHCI under copper-deficiency, showed the presence of most of the LHCI spots in the former but their absence in the latter. Our data demonstrate that (i) hydrophobic membrane proteins like the LHCPs can be faithfully separated by 2-DE, and (ii) that high-resolution 2-DE facilitates the comparative analysis of membrane protein complexes in wild-type and mutants cells.