Professor
Petya Violinova KRASTEVA
Structural Biology of Biofilms Group, European Institute of Chemistry and Biology (IECB), CNRS CBMN UMR5248, University Bordeaux, France
Title of the talk: Weaving of bacterial cellulose by the Bcs secretion systems
Abstract
Cellulose is the most abundant biopolymer on Earth and while it is the predominant constituent of plants, it is also a key extracellular matrix component in many bacterial species, thus providing resistance and fitness advantages in a variety of free-living and pathogenic species. While bacterial cellulose (BC) was first described in the 19th century, it was not until this last decade that insights were provided into how the cellulose synthase BcsA, assisted by its inner-membrane partner BcsB, senses c-di-GMP to simultaneously polymerize its substrate and extrude the nascent polysaccharide across the inner bacterial membrane. It is now established that BC can be produced by several distinct types of cellulose secretion systems and that in addition to BcsAB, they can feature multiple accessory subunits, often indispensable for polysaccharide production. Importantly, in the last years we have made significant progress in elucidating not only cellulose polymerization per se but also the bigger picture of bacterial signaling, secretion system assembly, and bacterial biofilm formation. In Escherichia coli, the BcsAB tandem assembles into a stable megadalton-sized macrocomplex with five accessory subunits, which are either essential for or enhance the secretion of a phosphoethanolamine (pEtN)-modified biomatrix polymer. In other bacteria secreting crystalline, semi-crystalline or acetylated, crystallinity is determined by supramolecular arrangement of the Bcs terminal complexes, itself driven by two accessory subunits, BcsD and a proline-rich partner (BcsH/P/O). I will present recent structural and functional data providing in-depth mechanistic insights into the Bcs secretion systems of these two important model organisms.
Biography
Petya Krasteva completed her PhD in Molecular and Cell Biology at Ivy League’s Cornell University in January 2011, after which she joined the editorial team of Nature Methods at Nature Publishing Group, New York. For her postdoc, she moved to the Institut Pasteur in Paris in 2012 and started her independent “Structural Biology of Biofilms’ group at the nearby CNRS Institute of Integrative Biology of the Cell (I2BC) in 2016. Since 2019 her team is based in the European Institute of Chemistry and Biology at the vibrant Bordeaux metropolitan area in southwest France.
The Krasteva Lab’s research focuses on cyclic dinucleotide signaling and extracellular matrix secretion in bacterial biofilm formation and pathogenesis. Combining X-ray crystallography, biophysical and biochemical assays, cryo-electron microscopy and in cellular functional studies, the ‘Structural Biology of Biofilms’ team aims to provide a comprehensive view of bacterial social networks that spans the different resolution levels and present molecular blueprints for the development of novel anti-infectives. For her work on bacterial signaling and biofilm formation, Petya Krasteva is the recipient of the Prix Jacques Monod (Fondation de France, 2016), a CNRS Médaille de Bronze (2019) and an ERC Starting Grant (BioMatrix, 2018-2024).
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