Mikael Elias, PhD

Cellular phosphate uptake and bacterial virulence

Phosphorus is indispensable for life, but its bio-availability is limited. Consequently, environmental phosphate concentrations are rather low (~1uM or below), whereas intracellular concentrations are very high (> 10mM). The challenge is not only to extract phosphate, but also to discard competing, possibly toxic anions such as arsenate. This is mainly achieved in prokaryotes by the phosphate specific transporter (Pst), an interesting transporter that evolved to address the various challenges of dramatically different environments. Our group is particularly interested in deciphering the molecular mechanism of the phosphate translocation through the membrane. Moreover, we are studying the cellular mechanism of phosphate concentration sensing, and the consequences on the regulation of bacterial growth, and bacterial virulence.

From chemical bonds to phenotypes

Chemical bonds comprise very diverse types of interactions in biomolecules, including weak, strong, short or long range bonds. They are often thousands within a single biomolecules, but just a few, or sometimes one can be directly responsible for a biological function or an organismal phenotype. Our group have isolated some unique chemical bonds in phosphate-binding proteins, responsible for the ability of extreme microbes to thrive in arsenate-rich environment by excluding the latter and binding phosphate instead. These bonds are characterized using ultra high quality, Sub-Ångstrom X-ray crystallography and various spectroscopic methods.  They revealed an astonishing and unexpected complexity, being unusually short and energetic. The understanding of the chemistry involved here is a key feature in protein design and bioengineering.

Molecular engineering of enzymes and biotechnological applications

The group is interested in various enzymes, including some promiscuous representatives of lactonases from extremophilic organisms (e.g. PLL). These enzymes, by hydrolyzing bacterial signaling molecules (e.g. acyl-homoserine lactones (AHLs) have the ability to quench the bacterial communication system, also known as quorum sensing. As a result, some bacterial populations treated with such enzymes are impaired for expressing virulence factors or forming biofilms, opening the possibility of developing a broad range of applications, from antibacterial plasters to protective treatments of crops.

Additionally, the group is working to improve through structure-based, combinatorial libraries, the promiscuous phosphotriesterase activity of these enzymes. Such enzyme have the ability to decontaminate the toxic organophosphorous pesticides, and therefore offer a soft, green solution for the bioremediation of these chemicals.

The research carried out in the Lab includes a large combination of techniques, spanning from molecular biology and microbiology, to protein engineering, structural biology and bioinformatics.