Research

Protein acetylation in bacteria

N-Terminal protein acetylation is one of the most common protein post-translational modifications in eukaryotes but rare in prokaryotes. This protein modification is catalyzed by a range of N-acetyltransferases (NATs) that transfer acetyl groups from acetyl-coenzyme A to the α-amino group of an amino-terminal residue. Growing evidence suggests that N-acetylation plays a pivotal role in the stability, activity and targeting of certain proteins. Although most eukaryotic proteins are not acetylated when expressed in E. coli, partial or complete N-acetylation has been reported for several ectopic recombinant proteins. For most of these proteins, however, the underlying mechanism of N-terminal acetylation has remained unknown.

We are studying the mechanism of this protein modification, with an ultimate goal to express either acetylated or non-acetylated proteins at our will.

 

New molecules to probe and modulate riboswitches

Riboswitches are mRNA structures that control gene expression mainly in bacteria. These recently characterized RNA molecules can specifically bind their cognate metabolites, inducing conformational changes that ultimately lead to the negative or positive regulation of the genes associated with the biosynthesis, transport, or degradation of the metabolites. To date, more than 20 distinct classes of riboswitches have been discovered for many different cellular metabolites, including thiamine pyrophosphate (TPP), flavin mononucleotide (FMN)  S-adenosylmethionine (SAM), tetrahydrofolate, cobalamine,  glucosamine 6-phosphate (GlcN6P), guanine, adenine, glycine, and lysine. Mainly found in bacteria, these novel classes of RNA molecules have attracted attention as novel antibiotic targets.

We are currently developing small molecules that probe and modulate bacterial riboswitches. Once developed, these molecules will provide important tools to study riboswitch-mediated biochemical and cellular processes, and ultimately could provide a molecular basis for the development of new antibiotic drugs.

 

RNA-based biosensors

Aptamers are structured DNA and RNA molecules that bind to specific ligands with high affinity and selectivity. During the last two decades, a test tube evolution technique, called SELEX (Systematic Evolution of Ligands by Exponential Enrichment), has offered a breakthrough for developing engineered aptamers that bind to a number of different target ligands, including small molecules, proteins, nucleic acids, and cells for various analytical and therapeutic applications. In recent years, a few synthetic riboswitches have been constructed from existing RNA aptamers. Engineered riboswitches offer a new tool to control gene expression in response to exogenous molecules not only in bacteria but also in eukaryotes.

We are currently developing a novel set of general in vitro and in vivo selection/screening methods to develop synthetic riboswitches as novel tools to regulate gene expression and as new RNA-based biosensors.