scholarly journals Selective cross-linking of coinciding protein assemblies by in-gel cross-linking mass-spectrometry

2020 ◽  
Author(s):  
Johannes F. Hevler ◽  
Marie V. Lukassen ◽  
Alfredo Cabrera-Orefice ◽  
Susanne Arnold ◽  
Matti F. Pronker ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Structural Model ◽  
Protein Complexes ◽  
Protein Structures ◽  
Substantial Reduction ◽  
Cross Linking ◽  
Complement Components ◽  
Native Page ◽  
Blue Native Page ◽  
Cross Links

AbstractCross-linking mass spectrometry has developed into an important method to study protein structures and interactions. The in-solution cross-linking workflows involve time and sample consuming steps and do not provide sensible solutions for differentiating cross-links obtained from co-occurring protein oligomers, complexes, or conformers. Here we developed a cross-linking workflow combining blue native PAGE with in-gel cross-linking mass spectrometry (IGX-MS). This workflow circumvents steps, such as buffer exchange and cross-linker concentration optimization. Additionally, IGX-MS enables the parallel analysis of co-occurring protein complexes using only small amounts of sample. Another benefit of IGX-MS observed by experiments on GroEL and purified bovine heart mitochondria, is the substantial reduction of artificial over-length cross-links when compared to in-solution cross-linking. We next used IGX-MS to investigate the complement components C5, C6, and their hetero-dimeric C5b6 complex. The obtained cross-links were used to generate a refined structural model of the complement component C6, resembling C6 in its inactivated state. This finding shows that IGX-MS can be used to provide new insights into the initial stages of the terminal complement pathway.

scholarly journals Driving integrative structural modeling with serial capture affinity purification

2020 ◽  
Vol 117 (50) ◽  
pp. 31861-31870
Author(s):  
Xingyu Liu ◽  
Ying Zhang ◽  
Zhihui Wen ◽  
Yan Hao ◽  
Charles A. S. Banks ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Structural Model ◽  
Protein Complexes ◽  
Affinity Purification ◽  
Quantitative Imaging ◽  
Resonance Energy ◽  
Correlation Spectroscopy ◽  
Cross Linking ◽  
Affinity Enrichment

Streamlined characterization of protein complexes remains a challenge for the study of protein interaction networks. Here we describe serial capture affinity purification (SCAP), in which two separate proteins are tagged with either the HaloTag or the SNAP-tag, permitting a multistep affinity enrichment of specific protein complexes. The multifunctional capabilities of this protein-tagging system also permit in vivo validation of interactions using acceptor photobleaching Förster resonance energy transfer and fluorescence cross-correlation spectroscopy quantitative imaging. By coupling SCAP to cross-linking mass spectrometry, an integrative structural model of the complex of interest can be generated. We demonstrate this approach using the Spindlin1 and SPINDOC protein complex, culminating in a structural model with two SPINDOC molecules docked on one SPIN1 molecule. In this model, SPINDOC interacts with the SPIN1 interface previously shown to bind a lysine and arginine methylated sequence of histone H3. Our approach combines serial affinity purification, live cell imaging, and cross-linking mass spectrometry to build integrative structural models of protein complexes.

scholarly journals Sequential digestion with Trypsin and Elastase in cross-linking/mass spectrometry

2018 ◽  
Author(s):  
Therese Dau ◽  
Kapil Gupta ◽  
Imre Berger ◽  
Juri Rappsilber
Keyword(s):  
Mass Spectrometry ◽  
Protein Interactions ◽  
Protein Structures ◽  
Cross Linking ◽  
Cleavage Sites ◽  
Protein Modelling ◽  
Protein Protein Interactions ◽  
Important Approach ◽  
Cross Links ◽  
Sequential Digestion

ABSTRACTCross-linking/mass spectrometry has become an important approach for studying protein structures and protein-protein interactions. The amino acid composition of some protein regions impedes the detection of cross-linked residues, although it would yield invaluable information for protein modelling. Here, we report on a sequential digestion strategy with trypsin and elastase to penetrate regions with a low density of trypsin cleavage sites. We exploited intrinsic substrate recognition properties of elastase to specifically target larger tryptic peptides. Our application of this protocol to the TAF4-12 complex allowed us to identify cross-links in previously inaccessible regions.

scholarly journals Structural dynamics of the human COP9 signalosome revealed by cross-linking mass spectrometry and integrative modeling

2020 ◽  
Vol 117 (8) ◽  
pp. 4088-4098 ◽  
Author(s):  
Craig Gutierrez ◽  
Ilan E. Chemmama ◽  
Haibin Mao ◽  
Clinton Yu ◽  
Ignacia Echeverria ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Structural Dynamics ◽  
Structural Changes ◽  
Structural Model ◽  
Protein Complexes ◽  
Cop9 Signalosome ◽  
Cross Linking ◽  
E3 Ligases ◽  
Protein Ubiquitination ◽  
Mass Spectometry

The COP9 signalosome (CSN) is an evolutionarily conserved eight-subunit (CSN1–8) protein complex that controls protein ubiquitination by deneddylating Cullin-RING E3 ligases (CRLs). The activation and function of CSN hinges on its structural dynamics, which has been challenging to decipher by conventional tools. Here, we have developed a multichemistry cross-linking mass spectrometry approach enabled by three mass spectometry-cleavable cross-linkers to generate highly reliable cross-link data. We applied this approach with integrative structure modeling to determine the interaction and structural dynamics of CSN with the recently discovered ninth subunit, CSN9, in solution. Our results determined the localization of CSN9 binding sites and revealed CSN9-dependent structural changes of CSN. Together with biochemical analysis, we propose a structural model in which CSN9 binding triggers CSN to adopt a configuration that facilitates CSN–CRL interactions, thereby augmenting CSN deneddylase activity. Our integrative structure analysis workflow can be generalized to define in-solution architectures of dynamic protein complexes that remain inaccessible to other approaches.

scholarly journals Structure-based validation can drastically under-estimate error rate in proteome-wide cross-linking mass spectrometry studies

2019 ◽  
Author(s):  
Kumar Yugandhar ◽  
Ting-Yi Wang ◽  
Shayne D. Wierbowski ◽  
Elnur Elyar Shayhidin ◽  
Haiyuan Yu
Keyword(s):  
Mass Spectrometry ◽  
Protein Interactions ◽  
Protein Complexes ◽  
Error Rates ◽  
Cross Linking ◽  
Protein Protein Interactions ◽  
3D Structures ◽  
Cross Links ◽  
Assess Quality ◽  
Almost All

AbstractRecent, rapid advances in cross-linking mass spectrometry (XL-MS) has enabled detection of novel protein-protein interactions and their structural dynamics at the proteome scale. Given the importance and scale of the novel interactions identified in these proteome-wide XL-MS studies, thorough quality assessment is critical. Almost all current XL-MS studies validate cross-links against known 3D structures of representative protein complexes. However, current structure validation approach only includes cross-links where both peptides mapped to the 3D structures. Here we provide theoretical and experimental evidence demonstrating this approach can drastically underestimate error rates for proteome-wide XL-MS datasets. Addressing current shortcomings, we propose and demonstrate a comprehensive set of four metrics, including orthogonal experimental validation to thoroughly assess quality of proteome-wide XL-MS datasets.

scholarly journals PhoX – an IMAC-enrichable Crosslinking Reagent

2019 ◽  
Author(s):  
Barbara A. Steigenberger ◽  
Roland J. Pieters ◽  
Albert J.R. Heck ◽  
Richard A. Scheltema
Keyword(s):  
Mass Spectrometry ◽  
Ribosomal Proteins ◽  
Structural Model ◽  
Structural Information ◽  
Protein Complexes ◽  
Protein Structures ◽  
Measurement Time ◽  
Close Proximity ◽  
Stoichiometric Reaction ◽  
Crosslinking Reagent

AbstractChemical crosslinking mass spectrometry is rapidly emerging as a prominent technique to study protein structures. Structural information is obtained by covalently connecting peptides in close proximity by small reagents and identifying the resulting peptide pairs by mass spectrometry. However, sub-stoichiometric reaction efficiencies render routine detection of crosslinked peptides problematic. Here we present a new tri-functional crosslinking reagent, termed PhoX, which is decorated with a stable phosphonic acid handle. This makes the crosslinked peptides amenable to the well-established IMAC enrichment. The handle allows for 300x enrichment efficiency and 97% specificity, dramatically reducing measurement time and improving data quality. We exemplify the approach on various model proteins and protein complexes, e.g. resulting in a structural model of the LRP1/RAP complex. PhoX is also applicable to whole cell lysates. When focusing the database search on ribosomal proteins, our first attempt resulted in 355 crosslinks, out-performing current efforts in less measurement time.

scholarly journals Quantitative Cross-Linking of Proteins and Protein

2021 ◽  
pp. 385-400
Author(s):  
Marie Barth ◽  
Carla Schmidt
Keyword(s):  
Mass Spectrometry ◽  
Protein Dynamics ◽  
Structural Changes ◽  
Structural Information ◽  
Protein Complexes ◽  
Cross Linking ◽  
Amino Acid Residues ◽  
Wide Range ◽  
Close Proximity ◽  
Cross Links

AbstractCross-linking, in general, involves the covalent linkage of two amino acid residues of proteins or protein complexes in close proximity. Mass spectrometry and computational analysis are then applied to identify the formed linkage and deduce structural information such as distance restraints. Quantitative cross-linking coupled with mass spectrometry is well suited to study protein dynamics and conformations of protein complexes. The quantitative cross-linking workflow described here is based on the application of isotope labelled cross-linkers. Proteins or protein complexes present in different structural states are differentially cross-linked using a “light” and a “heavy” cross-linker. The intensity ratios of cross-links (i.e., light/heavy or heavy/light) indicate structural changes or interactions that are maintained in the different states. These structural insights lead to a better understanding of the function of the proteins or protein complexes investigated. The described workflow is applicable to a wide range of research questions including, for instance, protein dynamics or structural changes upon ligand binding.

scholarly journals Driving Integrative Structural Modeling with Serial Capture Affinity Purification

2020 ◽  
Author(s):  
Xingyu Liu ◽  
Ying Zhang ◽  
Zhihui Wen ◽  
Yan Hao ◽  
Charles A.S. Banks ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Structural Model ◽  
Protein Complexes ◽  
Affinity Purification ◽  
Quantitative Imaging ◽  
Specific Protein ◽  
Cross Linking ◽  
Affinity Enrichment

AbstractStreamlined characterization of protein complexes remains a challenge for the study of protein interaction networks. Here, we describe Serial Capture Affinity Purification (SCAP) where two separate proteins are tagged with either the HaloTag or the SNAP-tag, permitting a multi-step affinity enrichment of specific protein complexes. The multifunctional capabilities of these protein tagging systems also permit in vivo validation of interactions using FRET and FCCS quantitative imaging. When coupling SCAP to cross-linking mass spectrometry, an integrated structural model of the complex of interest can be generated. We demonstrate this approach using the Spindlin1 and SPINDOC chromatin associated protein complex, culminating in a structural model with two SPINDOC docked on one SPIN1 molecule. In this model, SPINDOC interacts with the SPIN1 interface previously shown to bind a lysine and arginine methylated sequence of histone H3 Taken together, we present an integrated affinity purification, live cell imaging, and cross linking mass spectrometry approach for the building of integrative structural models of protein complexes.

Statistical Force-Field for Structural Modeling Using Chemical Cross-Linking/mass Spectrometry Distance Constraints

2018 ◽  
Author(s):  
Allan J. R. Ferrari ◽  
Fabio C. Gozzo ◽  
Leandro Martinez
Keyword(s):  
Mass Spectrometry ◽  
Amino Acid ◽  
Force Field ◽  
Protein Structures ◽  
Protein Structure Determination ◽  
Structural Modeling ◽  
Cross Linking ◽  
Amino Acid Residues ◽  
Distance Constraints ◽  
Chemical Cross Linking

<div><p>Chemical cross-linking/Mass Spectrometry (XLMS) is an experimental method to obtain distance constraints between amino acid residues, which can be applied to structural modeling of tertiary and quaternary biomolecular structures. These constraints provide, in principle, only upper limits to the distance between amino acid residues along the surface of the biomolecule. In practice, attempts to use of XLMS constraints for tertiary protein structure determination have not been widely successful. This indicates the need of specifically designed strategies for the representation of these constraints within modeling algorithms. Here, a force-field designed to represent XLMS-derived constraints is proposed. The potential energy functions are obtained by computing, in the database of known protein structures, the probability of satisfaction of a topological cross-linking distance as a function of the Euclidean distance between amino acid residues. The force-field can be easily incorporated into current modeling methods and software. In this work, the force-field was implemented within the Rosetta ab initio relax protocol. We show a significant improvement in the quality of the models obtained relative to current strategies for constraint representation. This force-field contributes to the long-desired goal of obtaining the tertiary structures of proteins using XLMS data. Force-field parameters and usage instructions are freely available at http://m3g.iqm.unicamp.br/topolink/xlff <br></p></div><p></p><p></p>

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