Recent Synthetic Biology Approaches for Temperature- and Light-Controlled Gene Expression in Bacterial Hosts

The expression of genes of interest (GOI) can be initiated by providing external stimuli such as temperature shifts and light irradiation. The application of thermal or light stimuli triggers structural changes in stimuli-sensitive biomolecules within the cell, thereby inducing or repressing gene expression. Over the past two decades, several groups have reported genetic circuits that use natural or engineered stimuli-sensitive modules to manipulate gene expression. Here, we summarize versatile strategies of thermosensors and light-driven systems for the conditional expression of GOI in bacterial hosts

Enhanced efficacy of 7-hydroxy-3-methoxycadalene via glycosylation in in vivo xenograft study

7-Hydroxy-3-methoxycadalene, isolated from Zelkova serrata Makino, was confirmed as a biologically active natural compound. In this study, the efficacy of cadalene as an anticancer agent was tested. In order to address the poor physicochemical properties of cadalene, we designed and synthesized glycosylated cadalene derivatives for improved solubility and efficient drug delivery as a potential prodrug. In vitro cell viability assays confirmed that glycosylated cadalenes were less toxic and more soluble than cadalene. In an in vivo xenograft study in mice, the oral administration of glycosylated cadalenes caused a significant reduction in tumor size.This work is supported by the Korea Science and Engineering Foundation (KOSEF); Molecular and Cellular BioDiscovery Research Program of the Ministry of Science and Technology (MOST); and MarineBio21, Ministry of Maritime Affairs and Fisheries, Korea (MOMAF). M.H.C. is supported by KOSEF (M20704000010-07M0400-01010). H.Y. Lee is grateful for the Seoul Science Fellowship award. H.Y. Lee, J.T. Kwon, and M. Koh are grateful for the BK21 fellowship award

Construction of Polyheterocyclic Benzopyran Library with Diverse Core Skeletons through Diversity-Oriented Synthesis Pathway: Part II

As a continuation of our previous report (<i>J. Comb. Chem.</i> <b>2010</b>, <i>12</i>, 548–558), we accomplished the diversity-oriented synthesis of polyheterocyclic small-molecule library with privileged benzopyran substructure. To ensure the synthetic efficiency, we utilized the solid-phase parallel platform and the fluorous-tag-based solution-phase parallel platform to construct a 284-member polyheterocyclic library with six distinct core skeletons with an average purity of 87% on a scale of 5–10 mg. This library was designed to maximize the skeletal diversity with discrete core skeletons in three-dimensional space and the combinatorial diversity with four different benzopyranyl starting materials and various building blocks. Together with our reported benzopyranyl library, we completed the construction of polyheterocyclic benzopyran library with 11 unique scaffolds and their molecular diversity was visualized in chemical space using principle component analysis (PCA)

Investigation of Specific Binding Proteins to Photoaffinity Linkers for Efficient Deconvolution of Target Protein

Photoaffinity-based target identification has received recent attention as an efficient research tool for chemical biology and drug discovery. The major obstacle of photoaffinity-based target identification is the nonspecific interaction between target identification probes and nontarget proteins. Consequently, the rational design of photoaffinity linkers has been spotlighted for successful target identification. These nonspecific interactions have been considered as random events, and therefore no systematic investigation has been conducted regarding nonspecific interactions between proteins and photoaffinity linkers. Herein, we report the protein-labeling analysis of photoaffinity linkers containing three photoactivatable moieties: benzophenone, diazirine, and arylazide. Each photoaffinity linker binds to a different set of proteins in a structure-dependent manner, in contrast to the previous conception. The list of proteins labeled by each photoaffinity linker was successfully used to eliminate the nonspecific binding proteins from target candidates, thereby increasing the success rate of target identification

Generation of an Orthogonal Protein–Protein Interface with a Noncanonical Amino Acid

We have engineered the protein interface of the <i>Escherichia coli</i> chorismate mutase (EcCM) homodimer to be dependent on incorporation of a noncanonical amino acid (ncAA) at residue 72. The large hydrophobic amino acid <i>p</i>-benzoyl phenylalanine (pBzF) was substituted for Tyr72, which led to a catalytically inactive protein. A library of five residues (Leu25′, Arg29′, Leu76, Ile80′ and Asp83′) surrounding pBzF72 was generated and subjected to a growth based selection in a chorismate mutase deficient strain. An EcCM variant (Phe25′, pBzF72, Thr76, Gly80′ and Tyr83′) forms a stable homodimer, has catalytic activity similar to the wild type enzyme, and unfolds with a <i>T</i>_m of 53 °C. The X-ray crystal structure reveals a pi–pi stacking and hydrogen bonding interactions that stabilize the new protein interface. The strategy described here should be useful for generating organisms that are dependent on the presence of a ncAA for growth

Investigation of Specific Binding Proteins to Photoaffinity Linkers for Efficient Deconvolution of Target Protein

Photoaffinity-based target identification has received recent attention as an efficient research tool for chemical biology and drug discovery. The major obstacle of photoaffinity-based target identification is the nonspecific interaction between target identification probes and nontarget proteins. Consequently, the rational design of photoaffinity linkers has been spotlighted for successful target identification. These nonspecific interactions have been considered as random events, and therefore no systematic investigation has been conducted regarding nonspecific interactions between proteins and photoaffinity linkers. Herein, we report the protein-labeling analysis of photoaffinity linkers containing three photoactivatable moieties: benzophenone, diazirine, and arylazide. Each photoaffinity linker binds to a different set of proteins in a structure-dependent manner, in contrast to the previous conception. The list of proteins labeled by each photoaffinity linker was successfully used to eliminate the nonspecific binding proteins from target candidates, thereby increasing the success rate of target identification