Biology subjects

Woerner, T. P.

Publications and source records attributed to Woerner, T. P..

5 recordsLinked to original sources

bioRxiv2024

To 200,000 m/z and beyond: native electron capture charge reduction mass spectrometry deconvolves heterogeneous signals in large biopharmaceutical analytes

Great progress has been made in the detection of large biomolecular analytes by native mass spectrometry, however characterizing highly heterogeneous samples remains challenging due to the presence of many overlapping signals from complex ion distributions. Electron-capture charge reduction (ECCR), in which a protein cation captures free electrons without apparent dissociation, can dealign overlapping signals by shifting the ions to lower charge states. The concomitant shift to higher m/z also facilitates the exploration of instrument upper m/z limits if large complexes are used. Here we perform native ECCR on the bacterial chaperonin GroEL and megadalton scale adeno-associated virus (AAV) capsid assemblies on the Q Exactive UHMR mass spectrometer. Charge reduction of AAV8 capsids by up to 90% pushes signals well above 100,000 m/z and enables charge state resolution and mean mass determination of these highly heterogeneous samples, even for capsids loaded with genetic cargo. With minor instrument modifications the UHMR can detect charge reduced ion signals beyond 200,000 m/z. This work demonstrates the utility of ECCR for deconvolving heterogeneous signals in native mass spectrometry and presents the highest m/z signals ever recorded on an Orbitrap instrument, opening up the use of Orbitrap native mass spectrometry for heavier analytes than ever before.

molecular biology↗

bioRxiv2021

Assessment of genome packaging in AAVs using Orbitrap-based charge detection mass spectrometry

Adeno-associated viruses (AAV) represent important gene therapy vectors with several approved clinical applications and numerous more in clinical trials. Genome packaging is an essential step in the bioprocessing of AAVs and needs to be tightly monitored to ensure the proper delivery of transgenes and the production of effective drugs. Current methods to monitor genome packaging have limited sensitivity, a high demand on labour, and struggle to distinguish between packaging of the intended genome or unwanted side-products. Here we show that Orbitrap based charge detection mass spectrometry allows the ultra-sensitive quantification of all these different AAV bioprocessing products. A protocol is presented that allows the quantification of genome packed AAV preparations in under half an hour, requiring only micro-liter quantities of typical AAV preparations with ~1013 viral genome copies per millilitre. The method quickly assesses the integrity and amount of genome packed AAV particles to support AAV bioprocessing and characterization of this rapidly emerging class of advanced drug therapies.

biochemistry↗

bioRxiv2021

Frequency chasing of individual megadalton ions in an Orbitrap analyzer improves precision of analysis in single molecule mass spectrometry

To enhance the performance of charge detection mass spectrometry, we investigated the behavior of macromolecular single ions on their paths towards and within the Orbitrap analyzer. We discovered that ions in mass beyond one megadalton reach a plateau of stability and can be successfully trapped for seconds, travelling a path length of multiple kilometers, thereby enabling precise mass analysis with an effective resolution of greater than 100,000 at m/z 35,000. Through monitoring the frequency of individual ions, we show that these high mass ions, rather than being lost from the trap, can gradually lose residual solvent molecules and, in rare cases, a single elementary charge. Our observations highlight the importance of efficient desolvation for optimal charge detection mass spectrometry and inspired us to implement multiple improved data acquisition strategies. We demonstrate that the frequency drift of single ions due to desolvation and charge stripping can be corrected, which improves the effective ion sampling 23-fold and gives a two-fold improvement in mass precision and resolution, as demonstrated in the analysis of various viral particles.

biophysics↗

bioRxiv2020

Adeno-associated virus capsid assembly is divergent and stochastic

Adeno-associated viruses (AAVs) are small, non-enveloped, and have a T=1 icosahedral capsid. They belong to the Parvoviridae, genus Dependoparvovirus. Interest in AAVs has grown over recent years as they have emerged as promising gene therapy vectors. The AAV capsid, encapsulating the transgene, consists, in total, of 60 subunits made up from three distinct viral proteins (VPs) originating from the same cap gene (VP1, VP2, and VP3), which vary only in their N-terminus. While all three VPs play a crucial and specific role in cell-entry and transduction, their exact stoichiometry and organization in AAV capsids has, despite the availability of several high-resolution structures remained elusive. Here we obtained a set of native mass spectra of intact AAV capsids (Mw {approx} 3.8 MDa) that display both highly resolved regions and regions wherein interferences occur. Through spectrum simulation we resolved and elucidated this spectral complexity, allowing us to directly assess the VP stoichiometries in a panel of serotypes from different production platforms. The data reveals an extremely heterogeneous population of capsids of variable composition. The relative abundance for each of the hundreds of co-occurring capsid compositions is accurately described by a model based upon stochastic assembly from a mixed pool of expressed VP1, VP2, and VP3. We show that even the single-most abundant VP stoichiometry represents only a few percent of the total AAV population. We estimate that virtually every AAV capsid in a particular preparation has a unique composition and arrangement, i.e. no particle is identical. The systematic scoring of the stochastic assembly model against experimental high-resolution native MS data offers a sensitive and accurate new method to characterize these exceptionally heterogeneous gene-delivery vectors.

biochemistry↗

bioRxiv2019

Resolving heterogeneous high-mass macromolecular machineries by Orbitrap-based single particle charge detection mass spectrometry

Here we show that single particle charge-detection mass spectrometry (CD-MS) can be performed on a ubiquitous Orbitrap mass analyser and applied to the analysis of high-mass (megadalton) heterogeneous biomolecular assemblies. We demonstrate that single particle high-mass ions can survive in the Orbitrap for seconds, whereby their measured signal amplitudes scale linearly with charge state over the entire m/z range. Orbitrap based single particle CD-MS can be used to resolve mixed ion populations, accurately predict charge states, and consequently also the mass of the ions. We successfully applied CD-MS to challenging natural and biotherapeutic protein assemblies, such as IgM oligomers, designed protein nano-cages, ribosome particles and intact, empty- and genome-loaded Adeno-associated virus particles. Single particle CD-MS combined with native MS on existing Orbitrap platforms will greatly expand its application, especially in the mass analysis of megadalton heterogeneous biomolecular assemblies.

biophysics↗