Graduate Students Mini-Symposium I 2025

Graduate Students Mini-Symposium

  • Date: Feb 17, 2025
  • Time: 01:15 PM (Local Time Germany)
  • Location: MPI for Terrestrial Microbiology
  • Room: Lecture Hall / Hybrid
  • Host: IMPRS
  • Contact: imprs@mpi-marburg.mpg.de

13:15 h Pia Richter - AG Thanbichler
Functional characterization of the peptidoglycan recycling pathway in Caulobacter crescentus
Most bacteria possess a peptidoglycan (PG) cell wall that is required to withstand the turgor pressure and maintain cell shape. The PG layer needs to be constantly remodeled to enable the cells to elongate, grow and divide. During this process, small PG fragments are released into the periplasm. As these fragments can be used as a source for new PG building blocks, many bacteria take great effort in recycling these degradation products. Enterobacteria, such as Escherichia coli, for instance, reuse up to 60 % of released PG fragments. To this end, the turnover products are transported into the cytoplasm and further degraded by a set of PG recycling-specific enzymes.
While E. coli and other Gammaproteobacteria have rather simple shapes, the class of Alphaproteobacteria shows a variety of different cell shapes. In these organisms, correct PG remodeling and therefore also the availability of PG precursors seems to be even more important. One organism is C. crescentus, a crescent-shaped bacterium that is characterized by a biphasic life cycle involving to morphological distinct cell types and asymmetric cell division.
Here, we identified that C. crescentus has a functional PG recycling pathway, which is, although not necessary for general growth, essential to maintain proper cell shape. Additionally, we observed that PG recycling is needed to maintain the natural ß-lactam resistance of C. crescentus. By characterizing the so far unknown PG recycling mechanism in Alphaproteobacteria and understanding the connection between ß-lactam resistance and PG recycling, we aim to gain novel insights which can help uncovering potential treatments against pathogenic Alphaproteobacteria such as Bartonella or Brucella species.

13:45 h Trinetri Goel - AG Bode
Synthesis of structurally diverse peptide natural products from entomopathogenic bacteria for functional characterization
Natural products, such as non-ribosomal peptides and polyketides, are low molecular weight compounds produced by living organisms to serve complex functions such as signaling and defense.1,2 These organisms obtain an evolutionary advantage due to the high chemical diversity of natural products, inducing unique bioactive functions.1,3 Nevertheless, the bioactivity and function of many natural products remain unknown until today.4 Non-ribosomal peptides are a class of natural products biosynthesized by large multi-enzyme complexes called non-ribosomal peptide synthetase.1 Since Merrifield's development of the solid-phase peptide synthesis method in 19635, chemical synthesis has provided an efficient and streamlined approach to accessing a vast and diverse range of peptides, overcoming the difficulties associated with producing and purifying compounds in microbial hosts.6 Chemical synthesis offers several advantages over biotechnological production. These include a more straightforward purification process that does not contain media or cell components and is independent of low-production titers. Furthermore, synthesizing toxic compounds that would biotechnologically result in the death of the producer cell is possible. The synthesis, derivatization, and subsequent analysis of different peptide natural products derived from entomopathogenic bacteria aims to elucidate their structure-function relationship and identify novel natural products and new-to-nature peptides.

14:15 h Max Schreiber - AG Bode
Utilizing A-domains in NRPS engineering to incorporate reactive, non-natural amino acids into non-ribosomal peptides
Non-ribosomal peptides (NRP), produced by non-ribosomal peptide synthetases (NRPS), are a highly complex class of secondary metabolites characterized by a large functional and structural diversity. Due to their highly selective bioactivity, NRP are also increasingly used as drugs. However, they often need further structural modifications for pharmaceutical use. Direct incorporation of non-natural amino acids into NRP circumvent this issue and expand their chemical and structural properties even further.
Here, I present a fast guideline to efficiently identify promiscuous adenylation (A) domains. This strategy is based on in vivo feeding experiments paired with molecular network analysis to quickly identify novel NRP derivatives.
In contrast to in vitro assays such as the ADP/ATP exchange assay, no protein purification is required and in addition to the activation of non-natural amino acids by A domains, their transfer to the downstream T domain is monitored as well. Therefore, the identified A domains are likely to be functional in an engineered, synthetic NRPS. The corresponding A domains are assigned using high-resolution mass spectrometry fragmentation data. To efficiently exploit these promiscuous A domains in NRPS engineering, we utilize a novel evolution-inspired modular engineering strategy suitable for Golden Gate-based assembly of NRPS libraries. This allows us to produce a diverse range of synthetic NRP with novel chemical and structural properties.


Go to Editor View