Graduate Students Mini Symposium VII - 2023

13:15 h Jan Johannes Crames - AG Bode

Biosyntheses of unusual non-ribosomal peptides

The project elucidated the biosynthesis of two distinct unusual non-ribosomal peptides (NRPs), discovered by genome mining. The first part focused a rare bis-heterocyclic benzoxazolinate moiety, in Xenorhabdus and Photorhabdus, interacting with protein and DNA and thereby conferring extraordinary bioactivity. Additionally, unknown benzoxazolinate derivatives were identified in Pseudomonas chlororaphis subsp. piscium DSM 21509. A further part investigated the biosynthesis of rhabdobranin, a hybrid polyketide-NRP in Xenorhabdus and Photorhabdus, with antimicrobial properties, activated by a peptidase. The development of a large-scale in vitro conversion strategy using the pro-drug molecule facilitated isolation procedures, enabling the structural elucidation and the characterization of its bioactivity.

13:45 h Victoria Sajtovich - AG Erb

Explorations in Synthetic Metabolism: Regulation of PET Catabolism in Non-Model Microbe Ideonella sakaiensis

Waste streams such as polyethylene terephthalate (PET) represent a unique, circular carbon source for engineered microbes to produce value-added products. While considerable efforts have addressed fundamental enzymology and pathway transplantation in the case of PET, little research has been directed towards the microbe in which the complete degradation pathway was first elucidated. We report the genome assembly of Ideonella sakaiensis as well as transcriptional regulation of the terephthalic acid operon downstream of PET degradation. Progress on the domestication of I. sakaiensis through barcoded screening of functional origins of replication is additionally discussed, with promising implications for improving genetic tractability of other non-model microbes alongside I. sakaiensis.

14:15 h Wenhao Xu - AG Sourjik

Systematic mapping of bacterial receptor specificities from different species

Bacteria have evolved the ability to detect a wide range of environmental signals by using diverse signal transduction pathways, which are important for how bacteria interact with and respond to their environment. Although the conserved signaling cores of these pathways are well characterized, a large majority of diverse extracellular sensory domains (ESDs) and their signals remain unknown. Here we combined several in-vivo and in-vitro approaches to establish a systematic screening strategy for the identification of receptor ligands in P. aeruginosa, and we subsequently applied it to identify a number of new physiologically relevant ligands for ESDs from human gut microbiota.