The conformational and functional space of Lymphostatin

• Applicant: Professorin Dr. Bettina Böttcher
• Subject Area: Structural Biology
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 428774170

Enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC) cause pediatric diarrhea and infections, which can be life-threatening. EHEC and EPEC belong to a family of attaching and effacing (A/E) bacteria, which adhere intimately to enterocytes and destroy brush border microvilli. One of the virulence factors of these bacteria is lymphostatin, which has a molecular weight if 365 kDa and resembles AB-toxins. However, lymphostatin is not cell-toxic in contrast to AB-toxins. During the preceding funding period, we were able to determine the structure of lymphostatin, by electron cryo microscopy and image processing. We observed two L-shaped conformations with the N-terminal arm containing three catalytic domains and the C-terminal arm containing several β-sandwiches, which are reminiscent of receptor binding sites. In total, four potential catalytic domains were identified, comprising two glycosyltransferase domains, one protease domain and a C-terminal adenyl ribosyl-transferase domain. To date, no catalytic activity of lymphostatin has been demonstrated in vitro. The precise mechanism of lymphostatin activation, the cellular targets to which it acts and the manner of its attachment to these targets remain unknown. We propose to address these open questions through a comprehensive approach combining structural biology, biochemical assays, mass spectrometry and cell imaging.

• DFG Programme: Research Grants