title: Characterisation of an intrinsically disordered protein complex of Swi5-Sfr1 by ion mobility mass spectrometry and small-angle X-ray scattering.
abstract: It is now recognized that intrinsically disordered proteins (IDPs) play important roles as hubs in intracellular networks, and their structural characterisation is of significance. However, due to their highly dynamic features, it is challenging to investigate the structures of IDPs solely by conventional methods. In the present study, we demonstrate a novel method to characterise protein complexes using electrospray ionization ion mobility mass spectrometry (ESI-IM-MS) in combination with small-angle X-ray scattering (SAXS). This method enables structural characterisation even of proteins that have difficulties in crystallisation. With this method, we have characterised the Schizosaccharomyces pombe Swi5-Sfr1 complex, which is expected to have a long disordered region at the N-terminal portion of Sfr1. ESI-IM-MS analysis of the Swi5-Sfr1 complex revealed that its experimental collision cross-section (CCS) had a wide distribution, and the CCS values of the most dominant ions were ∼56% of the theoretically calculated value based on the SAXS low-resolution model, suggesting a significant size reduction in the gas phase. The present study demonstrates that the newly developed method for calculation of the theoretical CCSs of the SAXS low-resolution models of proteins allows accurate evaluation of the experimental CCS values of IDPs provided by ESI-IM-MS by comparing with the low-resolution solution structures. Furthermore, it was revealed that the combination of ESI-IM-MS and SAXS is a promising method for structural characterisation of protein complexes that are unable to crystallise.
authors: Graduate School of Nanobioscience, Yokohama City University, Yokohama, Kanagawa 230-0045, Japan.
authors: Kazumi
authors: K
authors: Saikusa
authors: Naoyuki
authors: N
authors: Kuwabara
authors: Yuichi
authors: Y
authors: Kokabu
authors: Yu
authors: Y
authors: Inoue
authors: Mamoru
authors: M
authors: Sato
authors: Hiroshi
authors: H
authors: Iwasaki
authors: Toshiyuki
authors: T
authors: Shimizu
authors: Mitsunori
authors: M
authors: Ikeguchi
authors: Satoko
authors: S
authors: Akashi
mesh_terms: D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism; D053838:Scattering, Small Angle; D012568:Schizosaccharomyces / Q000737:chemistry* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry* / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism; D014961:X-Ray Diffraction
chemical_list: D018797:Cell Cycle Proteins; C080218:SWI5 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C514357:Sfr1 protein, S pombe; D014157:Transcription Factors