Production of useful secondary metabolites in plants: Functional genomics approaches

The paradigm of biological research has been changed by recent developments in genomics, high-throughput biology, and bioinformatics. Conventional biology often was based on empirical, labor-intensive, and time-consuming methods. In the new paradigm, biological research e is driven by a holistic approach on the basis of rational, automatic, and high-throughput methods. New functional compounds can be discovered by using high-throughput screening systems. Secondary metabolite pathways and the genes involved in those pathways are then determined by studying functional genomics in conjunction with the data-mining tools of bioinformatics. In addition, these advances in metabolic engineering enable researchers to confer new secondary metabolic pathways to crops by transferring three to five, or more, heterologous genes taken from various other species. In the future, engineering for the production of useful compounds will be designed by a set of software tools that allows the user to specify a cell’s genes, proteins, and other molecules, as well as their individual interactions.     

Chemical biology approaches in plant stress research

In addition to their importance as essential agrochemicals and life-saving drugs, small molecules serve as powerful research tools to address questions at all levels of biological complexity from protein function to plant biotic interactions. In certain contexts, chemical tools are complementary or even preferred to genetic analysis, since not all experimental systems are amenable for genetic dissection. For example, mutants impaired in oxygen sensing cannot easily be recovered. Pharmacological and chemical genetics approaches have come to the rescue of biologists in unraveling such genetically intractable systems. In this review, I have discussed my own efforts to analyze oxygen deprivation signaling in plants to illustrate the validity of small molecular approaches in elucidating an essential pathway such as oxygen sensing. Chemical biology is also a potent approach to tease out genetically redundant biological processes. The recent breakthrough in identifying the elusive abscisic acid receptors has clearly demonstrated the power of chemical tools in dissecting redundant pathways and led to the blossoming of this area as a distinct discipline of plant biology research. I present a summary of this work and conclude the review with potential challenges in using chemical tools.     

Residual dipolar couplings: Synergy between NMR and structural genomics

Structural genomics is on a quest for the structure and function of a significant fraction of gene products. Current efforts are focusing on structure determination of single-domain proteins, which can readily be targeted by X-ray crystallography, NMR spectroscopy and computational homology modeling. However, comprehensive association of gene products with functions also requires systematic determination of more complex protein structures and other biomolecules participating in cellular processes such as nucleic acids, and characterization of biomolecular interactions and dynamics relevant to function. Such NMR investigations are becoming more feasible, not only due to recent advances in NMR methodology, but also because structural genomics is providing valuable structural information and new experimental and computational tools. The measurement of residual dipolar couplings in partially oriented systems and other new NMR methods will play an important role in this synergistic relationship between NMR and structural genomics. Both an expansion in the domain of NMR application, and important contributions to future structural genomics efforts can be anticipated.     

植物化学遗传学：一种崭新的植物遗传学研究方法

化学遗传学（chemical genetics,也称为化学基因组学,chemical genomics）研究方法是利用生物活性小分子扰动蛋白分子互作过程来研究有关的生命现象,是常规遗传学研究方法的补充和延伸。化学遗传学在植物科学中的应用——植物化学遗传学的研究在短短几年内,凭借其作为一种新的遗传学研究方法所具备的独特优势（如能够克服常规遗传学研究中的遗传冗余、突变致死难题及可提供特异强度、作用时间点上的条件性遗传扰动等）,已开始解决一些植物分子生物学中长期存在的研究难题。本文就植物化学遗传学的一般原理及其方法,以及它作为一种新的遗传学研究方法的优势及特点作一个综述．     

Analysis of multiple compound–protein interactions reveals novel bioactive molecules

The discovery of novel bioactive molecules advances our systems‐level understanding of biological processes and is crucial for innovation in drug development. For this purpose, the emerging field of chemical genomics is currently focused on accumulating large assay data sets describing compound–protein interactions (CPIs). Although new target proteins for known drugs have recently been identified through mining of CPI databases, using these resources to identify novel ligands remains unexplored. Herein, we demonstrate that machine learning of multiple CPIs can not only assess drug polypharmacology but can also efficiently identify novel bioactive scaffold‐hopping compounds. Through a machine‐learning technique that uses multiple CPIs, we have successfully identified novel lead compounds for two pharmaceutically important protein families, G‐protein‐coupled receptors and protein kinases. These novel compounds were not identified by existing computational ligand‐screening methods in comparative studies. The results of this study indicate that data derived from chemical genomics can be highly useful for exploring chemical space, and this systems biology perspective could accelerate drug discovery processes.     

Recent advances in microfluidic technologies for biochemistry and molecular biologys

Advances in the fields of proteomics and genomics have necessitated the development of high-throughput screening methods (HTS) for the systematic transformation of large amounts of biological chemical data into an organized database of knowledge. Microfluidic systems are ideally suited for high-throughput biochemical experimentation since they offer high analytical throughput, consume minute quantities of expensive biological reagents, exhibit superior sensitivity and functionality compared to traditional micro-array techniques and can be integrated within complex experimental work flows. A range of basic biochemical and molecular biological operations have been transferred to chip-based microfluidic formats over the last decade, including gene sequencing, emulsion PCR, immunoassays, electrophoresis, cell-based assays, expression cloning and macromolecule blotting. In this review, we highlight some of the recent advances in the application of microfluidics to biochemistry and molecular biology.     

Molecular recognition with boronic acids—applications in chemical biology

Small molecules have long been used for the selective recognition of a wide range of analytes. The ability of these chemical receptors to recognise and bind to specific targets mimics certain biological processes (such as protein–substrate interactions) and has therefore attracted recent interest. Due to the abundance of biological molecules possessing polyhydroxy motifs, boronic acids—which form five-membered boronate esters with diols—have become increasingly popular in the synthesis of small chemical receptors. Their targets include biological materials and natural products including phosphatidylinositol bisphosphate, saccharides and polysaccharides, nucleic acids, metal ions and the neurotransmitter dopamine. This review will focus on the many ways in which small chemical receptors based on boronic acids have been used as biochemical tools for various purposes, including sensing and detection of analytes, interference in signalling pathways, enzyme inhibition and cell delivery systems. The most recent developments in each area will be highlighted.     

Chemical genomics and medicinal systems biology: chemical control of genomic networks in human systems biology for innovative medicine

With advances in determining the entire DNA sequence of the human genome, it is now critical to systematically identify the function of a number of genes in the human genome. These biological challenges, especially those in human diseases, should be addressed in human cells in which conventional (e.g. genetic) approaches have been extremely difficult to implement. To overcome this, several approaches have been initiated. This review will focus on the development of a novel "chemical genetic/genomic approach" that uses small molecules to "probe and identify" the function of genes in specific biological processes or pathways in human cells. Due to the close relationship of small molecules with drugs, these systematic and integrative studies will lead to the "medicinal systems biology approach" which is critical to "formulate and modulate" complex biological (disease) networks by small molecules (drugs) in human bio-systems.     

The Functional Genomics Experiment model (FuGE): an extensible framework for standards in functional genomics

The Functional Genomics Experiment data model (FuGE) has been developed to facilitate convergence of data standards for high-throughput, comprehensive analyses in biology. FuGE models the components of an experimental activity that are common across different technologies, including protocols, samples and data. FuGE provides a foundation for describing entire laboratory workflows and for the development of new data formats. The Microarray Gene Expression Data society and the Proteomics Standards Initiative have committed to using FuGE as the basis for defining their respective standards, and other standards groups, including the Metabolomics Standards Initiative, are evaluating FuGE in their development efforts. Adoption of FuGE by multiple standards bodies will enable uniform reporting of common parts of functional genomics workflows, simplify data-integration efforts and ease the burden on researchers seeking to fulfill multiple minimum reporting requirements. Such advances are important for transparent data management and mining in functional genomics and systems biology.     

Tandem photoaffinity labeling–bioorthogonal conjugation in medicinal chemistry

Photoaffinity labeling has a longstanding history as a powerful biochemical technique. However, photoaffinity labeling has significantly evolved over the past decade principally due to its coupling with bioorthogonal/click chemistry reactions. This review aims to highlight tandem photoaffinity labeling–bioorthogonal conjugation as a chemical approach in medicinal chemistry and chemical biology. In particular, recent examples of using this strategy for affinity-based protein profiling (AfBPP), drug target identification, binding ensemble profiling, studying endogenous biological molecules, and imaging applications will be presented. Additionally, recent advances in the development of ‘all-in-one’ compact moieties possessing a photoreactive group and clickable handle will be discussed.     

Genomics-enabled discovery of phosphonate natural products and their biosynthetic pathways

Phosphonate natural products have proven to be a rich source of useful pharmaceutical, agricultural, and biotechnology products, whereas study of their biosynthetic pathways has revealed numerous intriguing enzymes that catalyze unprecedented biochemistry. Here we review the history of phosphonate natural product discovery, highlighting technological advances that have played a key role in the recent advances in their discovery. Central to these developments has been the application of genomics, which allowed discovery and development of a global phosphonate metabolic framework to guide research efforts. This framework suggests that the future of phosphonate natural products remains bright, with many new compounds and pathways yet to be discovered.     

Can we build synthetic,multicellular systems by controlling developmental signaling in space and time?

Using biological machinery to make new, functional molecules is an exciting area in chemical biology. Complex molecules containing both 'natural' and 'unnatural' components are made by processes ranging from enzymatic catalysis to the combination of molecular biology with chemical tools. Here, we discuss applying this approach to the next level of biological complexity -- building synthetic, functional biotic systems by manipulating biological machinery responsible for development of multicellular organisms. We describe recent advances enabling this approach, including first, recent developmental biology progress unraveling the pathways and molecules involved in development and pattern formation; second, emergence of microfluidic tools for delivering stimuli to a developing organism with exceptional control in space and time; third, the development of molecular and synthetic biology toolsets for redesigning or de novo engineering of signaling networks; and fourth, biological systems that are especially amendable to this approach.     

Recent developments in molecular simulation approaches to study spherical virus capsids

Viruses are particularly challenging systems to study via molecular simulation methods. Virus capsids typically consist of over 100 subunit proteins and reach dimensions of over 100 nm; solvated viruses capsid systems can be over 1 million atoms in size. In this review, I will present recent developments which have attempted to overcome the significant computational expense to perform simulations which can inform experimental studies, make useful predictions about biological phenomena and calculate material properties relevant to nanotechnology design efforts.     

Bench to batch: advances in plant cell culture for producing useful products

Despite significant efforts over nearly 30 years, only a few products produced by in vitro plant cultures have been commercialized. Some new advances in culture methods and metabolic biochemistry have improved the useful potential of plant cell cultures. This review will provide references to recent relevant reviews along with a critical analysis of the latest improvements in plant cell culture, co-cultures, and disposable reactors for production of small secondary product molecules, transgenic proteins, and other products. Some case studies for specific products or production systems are used to illustrate principles.     

Chemical genomics: a challenge for de novo drug design

De novo design provides an in silico toolkit for the design of novel small molecular structures to a set of specified structural constraints. With the avalanche of bioinformatics data, de novo design is ideally suited for exploring molecules that could be useful for chemical genomics. The design process involves manipulation of the input, modification of structural constraints, and further processing of the de novo generated molecules using various modular toolkits. The development of a theoretical framework for each of these stages will provide novel practical solutions to the problem of creating compounds with maximal chemical diversity. This short review describes the fundamental problems encountered in the application of novel chemical design technologies to chemical genomics by means of a formal representation. This notation helps to outline and clarify ideas and hypotheses that can then be explored using mathematical algorithms. It is only by developing this rigorous foundation that in silico design can progress in a rational way.     

Genetically encoded RNA photoswitches as tools for the control of gene expression

An important goal in chemical and synthetic biology is controlling the expression of defined sets of genes by external stimuli, and one of the most attractive stimuli is light. Current approaches to the photocontrol of biological processes utilize photoresponsive proteins. In this article, I will illustrate the prospects of synthetic systems in which the receptor is a photoresponsive nucleic acid, and will review the different tools already in place to develop photoresponsive systems based on RNA. A particular focus is on genetically encoded photoswitches that can be expressed in prokaryotic or eukaryotic cells, and respond to photoisomerizable, cell-permeable small molecules.     

Tools for the discovery of biopolymer producing cysteine relays

Cysteine relays, where a protein or small molecule is transferred multiple times via transthiolation, are central to the production of biological polymers. Enzymes that utilise relay mechanisms display broad substrate specificity and are readily engineered to produce new polymers. In this review, I discuss recent advances in the discovery, engineering and biophysical characterisation of cysteine relays. I will focus on eukaryotic ubiquitin (Ub) cascades and prokaryotic polyhydroxyalkanoate (PHA) synthesis. These evolutionarily distinct processes employ similar chemistry and are readily modified for biotechnological applications. Both processes have been studied intensively for decades, yet recent studies suggest we do not fully understand their mechanistic diversity or plasticity. I will discuss the important role that activity-based probes (ABPs) and other chemical tools have had in identifying and delineating Ub cysteine-relays and the potential for ABPs to be applied to PHA synthases. Finally, I will offer a personal perspective on the potential of engineering cysteine-relays for non-native polymer production.     

Recent advances in target identification of bioactive natural products

Natural products are a tremendous source of tool discovery for basic science and drug discovery for clinical uses. In contrast to the large number of compounds isolated from nature, however, the number of compounds whose target molecules have been identified so far is fairly limited. Elucidation of the mechanism of how bioactive small molecules act in cells to induce biological activity (mode of action) is an attractive but challenging field of basic biology. At the same time, this is the major bottleneck for drug development of compounds identified in cell-based and phenotype-based screening. Although researchers’ experience and inspiration have been crucial for successful target identification, recent advancements in genomics, proteomics, and chemical genomics have made this challenging task possible in a systematic fashion.