New antibiotic development through exploration of the bacterial cell wall formation machinery

Abstract

Antibiotics have been used to treat infectious diseases for decades and are arguably the most successful drugs developed in history. However, the wide use and misuse of these drugs have selected multi-drug resistant organisms, allowing bacteria to proliferate even in their presence. Moreover, many resistance elements are readily spreading among different bacterial strains, increasing the specter of worldwide pandemics (Payne et al., 2007; Wright, 2007). The screening of novel natural product libraries is now being encouraged as a means to identify new antibacterial molecules (Lewis 2012). Thus, in the first year of my PhD project, I screened natural product libraries available at the LNBio, some of which contained compounds from the Brazillian biodiversity. I performed whole cell screens with Gram-positive and Gram-negative organisms, and I was able to identify numerous "hits", which included extracts, semi-purified fractions, as well as purified molecules that were able to block cell growth. Many of these hits are now being purified at the LNBio, and one of the objectives of this BEPE application is to characterize their mechanism of action and activity spectrum against pathogenic bacteria.A second objective of my BEPE project involves the direct study of novel antibiotic development targets within the bacterial cell wall biosynthesis machinery. Antibacterial agents that target the bacterial cell wall have been used effectively for the past 75 years (Bush, 2012) and include some of the most frequently used agents in clinical practice, including ²-lactams and glycopeptides. Thus, despite the widespread problem of resistance to some of these molecules, the cell wall continues to be an excep-tional target for novel inhibitor development. Our group has recently structurally and functionally characterized, for the first time, a complex between two components of the cell wall biosynthesis machinery of Helicobacter pylori, PBP2 and MreC (Contreras et al.,2017; Nature Commun.). The interface between the two proteins represents a totally new target for new antibiotic development, and the exploration of this complex in other human patho-gens, such as Escherichia coli and Pseudomonas aeruginosa, is a very exciting challenge. My advisor is the recipient of a Sao Paulo Excellence Chair and directs 2 laboratories, one in Campinas and one in Grenoble, France, and despite the fact that the PBP2:MreC work was done in partnership between the two groups, the structural part of the work was done in Grenoble. Thus, I would like to take the opportuni-ty of a BEPE fellowship at the IBS in Grenoble in order to also learn the structural biology aspect of this work.At the IBS, I will have the support not only of Dr. Dessen's research team, which has vast experience in structural biology and biochemistry, but I will also interact closely with the group of Dr. Ina Attree at the Biotechnology Institute of Grenoble. Dr. Attree's group is experienced in microbiology and genetics of human bacterial pathogens such as Pseudomonas aeruginosa, as well as in cytological profiling, drug activity measurements, and eukaryotic cell assays. This fellowship will thus give me a unique opportunity to expand my knowledge of biochemical, biophysical, and microbiological techniques, as well as to validate my identified 'hits' as potential novel inhibitors of bacterial growth and division.