Current Members

The Pel polysaccharide is a widespread biofilm component involved in chronic infections. It is produced by Gram-negative and Gram-positive bacteria and typically regulated by the second messenger c-di-GMP. Interestingly, Gram-positives contain a subset of species that lack genes required for the c-di-GMP pathway. My project aims to understand the underlying principles of Pel regulation and production in this subset using S. intermedius as model organism with the hope of finding an alternative treatment approach for Pel related infections.

Development of glycoside hydrolases as therapeutics.

Microbial biofilms are involved in many chronic infections. The microbial cells within these biofilms are enclosed in a self-produced polymeric matrix. Using biochemical techniques and cryoelectron microscopy, my work aims to understand at the molecular level the protein machinery that synthesizes exopolysaccharides, a major component of the biofilm matrix, such as Pel complex in S. intermedius, P. aeruginosa and B. cereus or the PgaAB complex that participates in the generation of Poly-β-1,6-N-acetyl-D-glucosamine (PNAG) in E. coli.

Microbial biofilms are involved in many chronic infections. The microbial cells within these biofilms are enclosed in a self-produced polymeric matrix. Using biochemical techniques and cryoelectron microscopy, my work aims to understand at the molecular level the protein machinery that synthesizes exopolysaccharides, a major component of the biofilm matrix, such as Pel complex in S. intermedius, P. aeruginosa and B. cereus or the PgaAB complex that participates in the generation of Poly-β-1,6-N-acetyl-D-glucosamine (PNAG) in E. coli.

Poly-β-1,6-N-acetyl-D-glucosamine (PNAG) is an exopolysaccharide essential for virulence and biofilm formation in both Gram-positive and Gram-negative bacteria. The polymerization and export of PNAG in gram-negative bacteria, such as E. coli and K. pneumoniae, is linked to a four-gene operon (pgaABCD). My project focuses on understanding the molecular mechanisms involved in the biosynthesis, modification, and export of PNAG by the membrane protein complexes PgaCD and PgaAB.

The Pel polysaccharide is a major component of the Pseudomonas aeruginosa biofilm produced by the pelABCDEFG operon, which contributes to its multi-antibiotic resistance. Previous studies have shown that PelA deacetylase activity is crucial for detection of Pel polymer produced by P. aeruginosa, and this activity is enhanced in the presence of the scaffolding protein PelB. My project aims to understand the mechanism of Pel processing and export by the PelAB complex. Using structural biology techniques such as cryo-EM and X-ray crystallography, I will focus on investigating structural changes induced in PelA upon complex formation with PelB, which can give insights on how PelB regulates PelA activity. Understanding the Pel biosynthetic complex mechanistically will allow us to develop targeted therapeutics against P. aeruginosa infections.

The cyclic dynamics of extension, surface adherence, and retraction of the Type IV pili (T4P) are powered largely by cytoplasmic motor ATPases via ATP hydrolysis. Previous studies in the T4aP system demonstrated the existence of multiple ATPases performing exclusive roles in either extension or retraction. Conversely, recent evidence in the Tad (tight adherence) system suggests that a bifunctional ATPase can drive both functions. Hence, my current project utilizes an X-ray crystallographic approach to determine the structure of the Tad pilus ATPase, leveraging C. crescentus as a model. The results will help us understand how structural differences amongst these ATPases ultimately produce varying functions.