Native Ion Mobility-Mass Spectrometry: from Flexible Proteins to Ion Channels

Abstract

After a brief introduction into the field of native mass spectrometry and ion mobility analysis of protein complexes, we discuss how high-mass modified instrumentation can give powerful insights into the stoichiometry, subunit composition, size and shape of biomolecular particles.We will show recent data on HFQ complexes which act as an RNA chaperone and are involved in the regulation of gene expression through facilitating post-transcriptional interactions between non-coding sRNAs and mRNA. The example of SMC proteins, which are crucial for Structural Maintenance of Chromosomes, illustrates the ability of ion mobility approaches to link information on complex assembly with the topology of the functional unit in heterogeneous systems.Recently, we have also been studying ion channels in detergent micelles and have been able to show the gradual opening of the Mechanosensitive Channel of Large Conductance in response to the binding of a charged drug molecule inside the channel which mimics the pressure on the bulk membrane. We show that we can characterize snapshots of the gradual opening of the channel, by using collision cross sections obtained from ion mobility measurements in combination with molecular modelling.