Our research is highly interdisciplinary at the interface of biology and physics further developing structural mass spectrometry (MS) to answer virological questions of high relevance to human health. This is also reflected by further affiliation of the head and several group members to DESY.

Being mainly interested in the structure and dynamics of viral protein complexes, the research aim is to elucidate, how these complex machineries function. We focus on the replication/transcription machinery of RNA viruses, namely coronaviruses, which often exist in many different states to mediate a diverse set of functions. Moreover, we are intrigued by viral particle assembly, where the low abundant intermediates are relevant to drug development but intrinsically hard to study. This work largely focusses on noroviruses, an important human pathogen, for which preventive treatments are still lacking. In capsid assembly, single particle-like approaches are best suited to deduce structural information.

Structural MS is becoming ever more popular as it requires low sample amounts and allows for automation, hence nicely opening up opportunities for systematic investigations of structural dynamics. We use and develop MS based techniques to achieve studying coexisting states in a time-resolved manner, following complementary routes: 1) basic structural information from structural MS; 2) solution structural models from native top-down MS; and 3) gas phase high resolution structures from X-ray free-electron lasers (XFEL). In the latter two cases, our MS based systems will allow selection to look at specific transient states and involve use of the different lightsources in Hamburg including PETRA III, FLASH I/II and the European XFEL. In terms of structural MS, we have native and hydrogen/deuterium exchange (HDX) MS established in the group with multiple protocols to tackle various research questions. The two methods are complementary with native MS providing information on the dynamics of quaternary assemblies and HDX MS delivering local structural information.

Research on coronaviruses made it back into the spotlight. As mentioned above coronaviral non-structural proteins (nsps) change structure and function dynamically during infection mediated amongst others by post-translational modifications (PTMs). In our native top-down MS approaches, we hope to correlate structure and PTMs, which is not easily possible by other means. We are expressing nsps with the aim to assemble larger complexes. Comparing bacterial to mammalian expression systems and different viral species will provide insights how PTMs alter assembly. In native MS, enzymatic activity can be directly monitored and at the same time reveal how the complexes shuttle between assembly states as has been performed on viral protease processing of regulatory polyprotein stretches.

For noroviruses, we focus on the viral capsids and how their structure is determined and altered throughout the viral lifecycle. We are currently working mainly with virus-like particles expanding on our work on partial capsid proteins, the P dimer. Thereby, we could reveal the distinct behaviour of various isolates in native and HDX MS. Using HDX MS, we can localize structural changes in the particles upon engagement of attachment factors. This way, we hope to decipher how human noroviruses enter cells and why cell culture production is so difficult. Our work on viral capsids will also largely benefit from single particle imaging at European XFEL and the developments from the EU EIC Pathfinder OPEN project MS SPIDOC and its successor MSCA DN SPIDoc’s.