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Best PhD Thesis 2013

Award attributed to Pedro Matos Pereira

Oeiras, 23.06.2014

Pedro Matos Pereira, who presented his PhD at ITQB last September, was awarded the Best PhD Thesis Prize 2013. The award ceremony will take place on the 27th of June, during the celebration of the ITQB Day.

For his PhD, Pedro Matos Pereira worked at the Bacterial Cell Biology under the supervision of Mariana Gomes Pinho. The thesis, entitled “Peptidoglycan assembly machines: The Staphylococcus aureus Penicillin-Binding Proteins”, focused on enzymes that catalyse the final steps of bacterial cell wall biosynthesis, which are targets for a wide range of antibiotics. Pedro is now Research Associate at the University College London.

The award, established in 2009, aims to recognize the best PhD thesis presented at ITQB each year. The prize money of 2,000 euros is funded by Fundação Jacqueline Dias de Sousa. The selection panel includes Carlos Bandeira Duarte from Universidade de Coimbra, Mário Nuno Berberan e Santos from Universidade Técnica de Lisboa, and is chaired by Cândido Pinto Ricardo from ITQB.


Summary of the PhD Thesis

The bacterial cell wall (CW) is of critical importance to cell viability. As there is no equivalent structure to the bacterial CW in mammalian cells, many important antibiotics target enzymes involved in its biosynthesis. The CW structure is mainly composed by two distinct polymers, peptidoglycan (PGN) and wall teichoic acids (WTA).

We are interested in the enzymes that catalyse the final steps of PGN biosynthesis, the penicillin-binding proteins (PBPs), which are targets for a wide range of antibiotics. We used as a model organism the human pathogen S. aureus, an extremely versatile pathogen, which has developed resistance to virtually all classes of available antibiotics, and is currently one of the most common causes of hospital-associated antibiotic resistant-infections.

In this thesis we have shown by fluorescence microscopy that PBPs are recruited to the division septum by different mechanisms, suggesting that each of these enzymes has to arrive at the midcell at a specific stage of the cell cycle. Additionally, we have shown that this recruitment involves not only PGN, synthesized by PBPs, but also WTA a polymer that is crucial in escaping immune-recognition by the host. These findings imply that: 1) for an accurate division, and ultimately for a successful infection, the biosynthesis of the several components of the bacterial surface must be tightly regulated 2) the PBPs seem to play an important role in this regulation by bridging the PGN and WTA biosynthesis pathways.

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