Unveiling the molecular coordination between the cell division machinery and S-layer biogenesis in Bacillus anthracis

Many bacteria possess a paracrystaline protein coat named the S-layer.

S-layers cover the entire cell surface and are involved in protection, virulence, cell-shape maintenance and communication.

Lattice integrity is essential for S-layer function, meaning that its assembly must be intimately coordinated with cell growth and division.

Some studies have reported that S-layer biogenesis co-localizes with peptidoglycan (PG) synthesis, however, the underlying molecular mechanisms remain unknown.

Here, I will investigate the molecular regulatory network that orchestrates S-layer assembly, cell division and PG synthesis in the human pathogen Bacillus anthracis, where S-layer defects render the bacterium avirulent, making this ultrastructure an attractive therapeutic target.In the SLYDIV project I will 1) structurally and functionally compare Sap and EA1, the exponential and stationary phase S-layer proteins of B. anthracis 2) follow their in vivo assembly using time-resolved labelling and fluorescent microscopy and 3) uncovering the molecular interactions that couple S-layer assembly with the PG and/or cell division machinery.

I will make use of chemicals that selectively target the cell cycle or cell division and monitor localization of S-layer assembly, will use nanobodies that disturb S-layer integrity and monitor the localization of cell wall synthesis, and use my interactomics experience to discover contact partners of S-layer and PG synthesis.

Thus, SLYDIV is a multidisciplinary and integrative project that combines structural biology, biophysics, cell imaging, and microbiology.

In addition, SLYDIV meets my solid knowledge on bacterial cell division with the host labs’ expertise on S-layer structure and function.

The SLYDIV project aims to lead to a major breakthrough in the basic understanding of the regulation of the bacterial cell envelope, while it will pave the way for specific novel molecular therapies against B. Anthracis, a Category A bioterrorist agent.