We are particularly interested in structural biology and the use of biophysical techniques to understand the function of enzymes or propose novel inhibitors that might contribute to the treatment of infectious diseases. In this context, we have two research proposals to explore the different strategies in the production of antimicrobials: natural product biosynthesis and fragment-based-drug discovery applied to key targets of microorganisms.
Natural Product Biosynthesis
Interest in Biosynthesis of Natural Products arouses from the efforts of Researchers around the World to understand how microorganisms are able to produce some very complicated molecules. Many of the antibiotics that are clinically relevant are, actually, natural products, in which a large number of them are produced by bacteria. Actinomycetes are a group of bacteria that are largely known for the number of bioactive molecules that they are able to produce. These organisms have different strategies to produce bioactive compounds, including the use of megasynthases such as Polyketide Synthases (PKSs) and Non-Ribosomal Peptide synthases (NRPSs). Other organisms are able to produce bioactive molecules derivated from the metabolism of sugar or even by modifying chorismate derivated compounds or even modifying ribosomally synthesized peptides (RIPPs). The enzymes that modify all these skeletons are called tailoring enzymes. We have a particular interest in these enzymes since most of these enzymes still need to be studied because of the recent burst of the number of characterized biosynthetic gene clusters from natural products. What calls our attention to these enzymes, is their peculiarities and applicability to synthetic biology to produce new antimicrobials. Examples of enzymes include cyclases that perform different reactions to closure rings in different classes of natural products, as ionophore polyethers. In addition, several of these enzymes have been proved to be powerful tools in the biocatalysis process for the development of novel antibiotics by increasing the promiscuity for chemical groups that such enzymes might add to a biosynthetic intermediate. In this context, our group has a strong interest in glycosyltransferases from the biosynthesis of different natural products and also in those enzymes involved in the biosynthesis of aminoglycosides, a largely used antibiotic for gram-negative bacteria infectious with disseminated resistance.
Fragment-Based Drug Discovery (FBDD)
The discovery of new molecules that could be used therapeutically is not only based on natural products but strategies of structure-based drug discovery have also been extensively used for several pharmaceutical companies. One approach to structure-based drug discovery is FBDD. FBDD approach relies on the screening of small compounds, generally smaller than 300 Da against key targets of a chosen disease using biophysical techniques, such as "differential Scanning Fluorometry" (DSF), "Nuclear Magnetic Resonance" (NMR), or "Surface Plasmonic Resonance" (SPR). A number of the compounds might be identified using one or more of these strategies. Generally, as these compounds are small, they are weak binders to the targets. However, using "Isothermal Calorimetry Titration" (ITC) or "MicroScale Thermophoresis" (DST), their affinity can be measured. Finally using protein crystallography, we can identify how these compounds bind to the target. Taken together all this information, we have enough material for the next step in the process of FBDD, which is the development of new and larger compounds based on the initial hits that should have a higher affinity. This technique consequently is a multidisciplinary approach to obtain new synthetic drugs, in which different backgrounds are needed. Targets of our interest include enzymes from Mycobacterium tuberculosis.