From Affinity to Proximity Techniques to Investigate Protein Complexes in Plants

The study of protein–protein interactions (PPIs) is fundamental in understanding the unique role of proteins within cells and their contribution to complex biological systems. While the toolkit to study PPIs has grown immensely in mammalian and unicellular eukaryote systems over recent years, application of these techniques in plants remains under-utilized. Affinity purification coupled to mass spectrometry (AP-MS) and proximity labeling coupled to mass spectrometry (PL-MS) are two powerful techniques that have significantly enhanced our understanding of PPIs. Relying on the specific binding properties of a protein to an immobilized ligand, AP is a fast, sensitive and targeted approach used to detect interactions between bait (protein of interest) and prey (interacting partners) under near-physiological conditions. Similarly, PL, which utilizes the close proximity of proteins to identify potential interacting partners, has the ability to detect transient or hydrophobic interactions under native conditions. Combined, these techniques have the potential to reveal an unprecedented spatial and temporal protein interaction network that better understands biological processes relevant to many fields of interest. In this review, we summarize the advantages and disadvantages of two increasingly common PPI determination techniques: AP-MS and PL-MS and discuss their important application to plant systems.

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PIPINO: A Software Package to Facilitate the Identification of Protein-Protein Interactions from Affinity Purification Mass Spectrometry Data

BioMed Research International ◽

10.1155/2016/2891918 ◽

2016 ◽

Vol 2016 ◽

pp. 1-13

Author(s):

Stefan Kalkhof ◽

Stefan Schildbach ◽

Conny Blumert ◽

Friedemann Horn ◽

Martin von Bergen ◽

...

Keyword(s):

Mass Spectrometry ◽

Protein Interactions ◽

Isotope Labeling ◽

Affinity Purification ◽

Interaction Network ◽

Mass Spectrometry Data ◽

Protein Protein Interactions ◽

Protein Protein Interaction ◽

Binding Behavior ◽

Bona Fide

The functionality of most proteins is regulated by protein-protein interactions. Hence, the comprehensive characterization of the interactome is the next milestone on the path to understand the biochemistry of the cell. A powerful method to detect protein-protein interactions is a combination of coimmunoprecipitation or affinity purification with quantitative mass spectrometry. Nevertheless, both methods tend to precipitate a high number of background proteins due to nonspecific interactions. To address this challenge the software Protein-Protein-Interaction-Optimizer (PIPINO) was developed to perform an automated data analysis, to facilitate the selection of bona fide binding partners, and to compare the dynamic of interaction networks. In this study we investigated the STAT1 interaction network and its activation dependent dynamics. Stable isotope labeling by amino acids in cell culture (SILAC) was applied to analyze the STAT1 interactome after streptavidin pull-down of biotagged STAT1 from human embryonic kidney 293T cells with and without activation. Starting from more than 2,000 captured proteins 30 potential STAT1 interaction partners were extracted. Interestingly, more than 50% of these were already reported or predicted to bind STAT1. Furthermore, 16 proteins were found to affect the binding behavior depending on STAT1 phosphorylation such as STAT3 or the importin subunits alpha 1 and alpha 6.

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Reliable identification of protein-protein interactions by crosslinking mass spectrometry

Nature Communications ◽

10.1038/s41467-021-23666-z ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Swantje Lenz ◽

Ludwig R. Sinn ◽

Francis J. O’Reilly ◽

Lutz Fischer ◽

Fritz Wegner ◽

...

Keyword(s):

Mass Spectrometry ◽

Protein Interactions ◽

Large Scale ◽

Structural Information ◽

Protein Complexes ◽

Interaction Network ◽

Protein Protein Interactions ◽

False Discovery Rates ◽

Large Scale Analysis ◽

Exit Tunnel

AbstractProtein-protein interactions govern most cellular pathways and processes, and multiple technologies have emerged to systematically map them. Assessing the error of interaction networks has been a challenge. Crosslinking mass spectrometry is currently widening its scope from structural analyses of purified multi-protein complexes towards systems-wide analyses of protein-protein interactions (PPIs). Using a carefully controlled large-scale analysis of Escherichia coli cell lysate, we demonstrate that false-discovery rates (FDR) for PPIs identified by crosslinking mass spectrometry can be reliably estimated. We present an interaction network comprising 590 PPIs at 1% decoy-based PPI-FDR. The structural information included in this network localises the binding site of the hitherto uncharacterised protein YacL to near the DNA exit tunnel on the RNA polymerase.

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Systematic Characterization of the Protein Interaction Network and Protein Complexes in Saccharomyces cerevisiae Using Tandem Affinity Purification and Mass Spectrometry

Methods in Molecular Biology - Yeast Functional Genomics and Proteomics ◽

10.1007/978-1-59745-540-4_11 ◽

2009 ◽

pp. 187-207 ◽

Cited By ~ 24

Author(s):

Mohan Babu ◽

Nevan J. Krogan ◽

Donald E. Awrey ◽

Andrew Emili ◽

Jack F. Greenblatt

Keyword(s):

Mass Spectrometry ◽

Saccharomyces Cerevisiae ◽

Protein Interaction ◽

Protein Interaction Network ◽

Protein Complexes ◽

Affinity Purification ◽

Interaction Network ◽

Tandem Affinity Purification

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Faculty Opinions recommendation of Sortase A mediated site-specific immobilization for identification of protein interactions in affinity purification-mass spectrometry experiments.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.725280481.793522616 ◽

2016 ◽

Author(s):

Morten Meldal ◽

Sanne Schoffelen

Keyword(s):

Mass Spectrometry ◽

Protein Interactions ◽

Affinity Purification ◽

Sortase A ◽

Site Specific ◽

Affinity Purification Mass Spectrometry

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RNA-Centric Approaches to Profile the RNA–Protein Interaction Landscape on Selected RNAs

Non-Coding RNA ◽

10.3390/ncrna7010011 ◽

2021 ◽

Vol 7 (1) ◽

pp. 11 ◽

Cited By ~ 1

Author(s):

André P. Gerber

Keyword(s):

Mass Spectrometry ◽

Protein Interactions ◽

Regulatory Networks ◽

Rna Binding ◽

Rna Binding Proteins ◽

Protein Complexes ◽

Cell Protein ◽

Transcriptional Regulatory Networks ◽

Technological Advances

RNA–protein interactions frame post-transcriptional regulatory networks and modulate transcription and epigenetics. While the technological advances in RNA sequencing have significantly expanded the repertoire of RNAs, recently developed biochemical approaches combined with sensitive mass-spectrometry have revealed hundreds of previously unrecognized and potentially novel RNA-binding proteins. Nevertheless, a major challenge remains to understand how the thousands of RNA molecules and their interacting proteins assemble and control the fate of each individual RNA in a cell. Here, I review recent methodological advances to approach this problem through systematic identification of proteins that interact with particular RNAs in living cells. Thereby, a specific focus is given to in vivo approaches that involve crosslinking of RNA–protein interactions through ultraviolet irradiation or treatment of cells with chemicals, followed by capture of the RNA under study with antisense-oligonucleotides and identification of bound proteins with mass-spectrometry. Several recent studies defining interactomes of long non-coding RNAs, viral RNAs, as well as mRNAs are highlighted, and short reference is given to recent in-cell protein labeling techniques. These recent experimental improvements could open the door for broader applications and to study the remodeling of RNA–protein complexes upon different environmental cues and in disease.

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Frequent assembly of chimeric complexes in the protein interaction network of an interspecies yeast hybrid

Molecular Biology and Evolution ◽

10.1093/molbev/msaa298 ◽

2020 ◽

Author(s):

Rohan Dandage ◽

Caroline M Berger ◽

Isabelle Gagnon-Arsenault ◽

Kyung-Mee Moon ◽

Richard Greg Stacey ◽

...

Keyword(s):

Protein Interactions ◽

Molecular Level ◽

Yeast Species ◽

Protein Complexes ◽

Mitochondrial Protein ◽

Chimeric Protein ◽

Interaction Network ◽

Protein Protein Interactions ◽

Extreme Phenotypes ◽

Yeast Hybrid

Abstract Hybrids between species often show extreme phenotypes, including some that take place at the molecular level. In this study, we investigated the phenotypes of an interspecies diploid hybrid in terms of protein-protein interactions inferred from protein correlation profiling. We used two yeast species, Saccharomyces cerevisiae and Saccharomyces uvarum, which are interfertile, but yet have proteins diverged enough to be differentiated using mass spectrometry. Most of the protein-protein interactions are similar between hybrid and parents, and are consistent with the assembly of chimeric complexes, which we validated using an orthogonal approach for the prefoldin complex. We also identified instances of altered protein-protein interactions in the hybrid, for instance in complexes related to proteostasis and in mitochondrial protein complexes. Overall, this study uncovers the likely frequent occurrence of chimeric protein complexes with few exceptions, which may result from incompatibilities or imbalances between the parental proteins.

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Mass spectrometry-based cross-linking study shows that the Psb28 protein binds to cytochrome b559 in Photosystem II

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1620360114 ◽

2017 ◽

Vol 114 (9) ◽

pp. 2224-2229 ◽

Cited By ~ 18

Author(s):

Daniel A. Weisz ◽

Haijun Liu ◽

Hao Zhang ◽

Sundarapandian Thangapandian ◽

Emad Tajkhorshid ◽

...

Keyword(s):

Mass Spectrometry ◽

Photosystem Ii ◽

Protein Interactions ◽

Protein Complexes ◽

Protein Docking ◽

Cross Linking ◽

Protein Protein Interactions ◽

Cytochrome B559 ◽

Reaction Center Complex ◽

Assembly Intermediate

Photosystem II (PSII), a large pigment protein complex, undergoes rapid turnover under natural conditions. During assembly of PSII, oxidative damage to vulnerable assembly intermediate complexes must be prevented. Psb28, the only cytoplasmic extrinsic protein in PSII, protects the RC47 assembly intermediate of PSII and assists its efficient conversion into functional PSII. Its role is particularly important under stress conditions when PSII damage occurs frequently. Psb28 is not found, however, in any PSII crystal structure, and its structural location has remained unknown. In this study, we used chemical cross-linking combined with mass spectrometry to capture the transient interaction of Psb28 with PSII. We detected three cross-links between Psb28 and the α- and β-subunits of cytochrome b559, an essential component of the PSII reaction-center complex. These distance restraints enable us to position Psb28 on the cytosolic surface of PSII directly above cytochrome b559, in close proximity to the QB site. Protein–protein docking results also support Psb28 binding in this region. Determination of the Psb28 binding site and other biochemical evidence allow us to propose a mechanism by which Psb28 exerts its protective effect on the RC47 intermediate. This study also shows that isotope-encoded cross-linking with the “mass tags” selection criteria allows confident identification of more cross-linked peptides in PSII than has been previously reported. This approach thus holds promise to identify other transient protein–protein interactions in membrane protein complexes.

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Characterization of major chromatin assembly proteins in tetrahymena thermophile using proeomic and molecular evolutionary analyses

10.32920/ryerson.14668284.v1 ◽

2021 ◽

Author(s):

Syed N Shah

Keyword(s):

Protein Interactions ◽

Protein Complexes ◽

Affinity Purification ◽

Regulation Of Gene Expression ◽

Chromatin Assembly ◽

Histone Chaperones ◽

Protein Protein Interactions ◽

Selective Forces ◽

Assembly Proteins

Histones H3/H4 are deposited onto DNA in a replication-dependent or independent fashion by the CAF1 and HIRA protein complexes. Despite the identification of these protein complexes, mechanistic details remain unclear. Recently, we showed that in T. thermophila histone chaperones Nrp1, Asf1 and the Impβ6 importin function together to transport newly synthesized H3/H4 from the cytoplasm to the nucleus. To characterize chromatin assembly proteins in T.thermophila, I used affinity purification combined with mass spectrometry to identify protein-protein interactions of Nrp1, Cac2 subunit of CAF1, HIRA and histone modifying Hat1-complex in T. thermophila. I found that the three-subunit T.thermophila CAF1 complex interacts with Casein Kinase 2 (CKII), possibly accounting for previously reported human CAF1phosphorylation. I also found that Hat2 subunit of HAT1 complex is also shared by CAF1 complex as its Cac3 subunit. This suggests that Hat2/Cac3 might exist in two separate pools of protein complexes. Remarkably, proteomic analysis of Hat2/Cac3 in turn revealed that it forms several complexes with other proteins including SIN3, RXT3, LIN9 and TESMIN, all of which have known roles in the regulation of gene expression. Finally, I asked how selective forces might have impacted on the function of proteins involved in H3/H4 transport. Focusing on NASP which possesses several TPR motifs, I showed that its protein-protein interactions are conserved in T. thermophila. Using molecular evolutionary methods I show that different TPRs in NASP evolve at different rates possibly accounting for the functional diversity observed among different family members.

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