Graduate Students Mini Symposium IV-2024

01:15 PM Maryia Ratnikava (AG Sourjik)

Systematic characterization of effects of multiple cell regulators on curli gene expression in E. coli

Curli amyloid fibers are the key component of E. coli biofilms produced at lower growth temperatures. Expression of curli depends on cellular response to diverse environmental conditions and is therefore heavily regulated on transcriptional and post-transcriptional levels. With the help of flow cytometry and plate reader analysis we systematically characterized the role of multiple transcriptional regulators and c-di-GMP-related proteins in expression of curli structural genes. For this, we created a library of deletion strains and examined their capacity to express curli, including kinetics of curli activation.

01:45 PM Sebastian Kaiser (AG Bode; MPRG Hochberg)

Recombination drives a molecular arms race between the bacteria and the bug

Nonribosomal peptidesynthetases are responsible for the production of medical relevant compounds such as penicillin. In this study we investigated the NRPS GameXPeptidesynthetase (GxpS) from bacteria of the genera Xenorhabdus and Photorhabdus that live in symbiotic relationship with entomopathogenic nematodes. We found that GameXPeptides have insecticidal activity by targeting Hsp90. Using recombination-aware phylogenetic methods and ancestral sequence reconstruction, we discovered a previously hidden diversity of GXP variants. Remarkably convergent changes of GXP structure across the phylogeny suggests that this diversity is driven by an arms race between GXP and its likely target HSP90.

02:15 PM Irina Lisevich (AG Sourjik)

Evolutionary optimization and adaptation of the bacterial motility and chemotaxis pathways

In my PhD project, which combines broad areas such as “bacterial economics”, evolutionary and synthetic biology, we investigate the constraints on gene expression levels using the well-studied E. coli motility and chemotaxis pathways as a model system. Our research addresses two main questions: (i) What constraints determine the expression levels of the entire flagellar cascade? (ii) How does the stoichiometry of individual protein components affect the functionality of the bacterial chemotaxis pathway? During the Symposium, I will present the main results we have obtained so far and give an outlook on the further development of the project.