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Abstract
The ferric uptake regulator (Fur) protein is the founding member of the FUR superfamily of metalloregulatory proteins that control metal homeostasis in bacteria. FUR proteins regulate metal homeostasis in response to the binding of iron (Fur), zinc (Zur), manganese (Mur), or nickel (Nur). FUR family proteins are generally dimers in solution, but the DNA-bound complex can involve a single dimer, a dimer-of-dimers, or an extended array of bound protein. Elevated FUR levels due to changes in cell physiology increase DNA occupancy and may also kinetically facilitate protein dissociation. Interactions between FUR proteins and other regulators are commonplace, often including cooperative and competitive DNA-binding interactions within the regulatory region. Further, there are many emerging examples of allosteric regulators that interact directly with FUR family proteins. Here, we focus on newly uncovered examples of allosteric regulation by diverse Fur antagonists (Escherichia coli YdiV/SlyD, Salmonella enterica EIIANtr, Vibrio parahaemolyticus FcrX, Acinetobacter baumannii BlsA, Bacillus subtilis YlaN, and Pseudomonas aeruginosa PacT) as well as one Zur antagonist (Mycobacterium bovis CmtR). Small molecules and metal complexes may also serve as regulatory ligands, with examples including heme binding to Bradyrhizobium japonicum Irr and 2-oxoglutarate binding to Anabaena FurA. How these protein-protein and protein-ligand interactions act in conjunction with regulatory metal ions to facilitate signal integration is an active area of investigation.
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Affiliation(s)
| | - John D. Helmann
- Department of Microbiology, Cornell University, Ithaca, New York, USA
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2
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Wicke D, Meißner J, Warneke R, Elfmann C, Stülke J. Understudied proteins and understudied functions in the model bacterium Bacillus subtilis-A major challenge in current research. Mol Microbiol 2023. [PMID: 36882621 DOI: 10.1111/mmi.15053] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 02/28/2023] [Accepted: 03/04/2023] [Indexed: 03/09/2023]
Abstract
Model organisms such as the Gram-positive bacterium Bacillus subtilis have been studied intensively for decades. However, even for model organisms, no function has been identified for about one fourth of all proteins. It has recently been realized that such understudied proteins as well as poorly studied functions set a limitation to our understanding of the requirements for cellular life, and the Understudied Proteins Initiative has been launched. Of poorly studied proteins, those that are strongly expressed are likely to be important to the cell and should therefore be considered high priority in further studies. Since the functional analysis of unknown proteins can be extremely laborious, a minimal knowledge is required prior to targeted functional studies. In this review, we discuss strategies to obtain such a minimal annotation, for example, from global interaction, expression, or localization studies. We present a set of 41 highly expressed and poorly studied proteins of B. subtilis. Several of these proteins are thought or known to bind RNA and/or the ribosome, some may control the metabolism of B. subtilis, and another subset of particularly small proteins may act as regulatory elements to control the expression of downstream genes. Moreover, we discuss the challenges of poorly studied functions with a focus on RNA-binding proteins, amino acid transport, and the control of metabolic homeostasis. The identification of the functions of the selected proteins not only will strongly advance our knowledge on B. subtilis, but also on other organisms since many of the proteins are conserved in many groups of bacteria.
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Affiliation(s)
- Dennis Wicke
- Department of General Microbiology, Georg-August-University Göttingen, GZMB, Göttingen, Germany
| | - Janek Meißner
- Department of General Microbiology, Georg-August-University Göttingen, GZMB, Göttingen, Germany
| | - Robert Warneke
- Department of General Microbiology, Georg-August-University Göttingen, GZMB, Göttingen, Germany
| | - Christoph Elfmann
- Department of General Microbiology, Georg-August-University Göttingen, GZMB, Göttingen, Germany
| | - Jörg Stülke
- Department of General Microbiology, Georg-August-University Göttingen, GZMB, Göttingen, Germany
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3
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Matzinger M, Vasiu A, Madalinski M, Müller F, Stanek F, Mechtler K. Mimicked synthetic ribosomal protein complex for benchmarking crosslinking mass spectrometry workflows. Nat Commun 2022; 13:3975. [PMID: 35803948 PMCID: PMC9270371 DOI: 10.1038/s41467-022-31701-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 06/21/2022] [Indexed: 11/09/2022] Open
Abstract
Cross-linking mass spectrometry has matured to a frequently used tool for the investigation of protein structures as well as interactome studies up to a system-wide level. The growing community generated a broad spectrum of applications, linker types, acquisition strategies and specialized data analysis tools, which makes it challenging to decide for an appropriate analysis workflow. Here, we report a large and flexible synthetic peptide library as reliable instrument to benchmark crosslink workflows. Additionally, we provide a tool, IMP-X-FDR, that calculates the real, experimentally validated, FDR, compares results across search engine platforms and analyses crosslink properties in an automated manner. We apply the library with 6 commonly used linker reagents and analyse the data with 6 established search engines. We thereby show that the correct algorithm and search setting choice is highly important to improve identification rate and reliability. We reach identification rates of up to ~70 % of the theoretical maximum (i.e. 700 unique lysine-lysine cross-links) while maintaining a real false-discovery-rate of <3 % at cross-link level with high reproducibility, representatively showing that our test system delivers valuable and statistically solid results. Cross-linking mass spectrometry is widely used to elucidate protein structures and interactions. Here, the authors generate an extensive peptide library to benchmark the most common cross-link search engines with frequently used cross-linking reagents in low and high complex sample systems.
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Affiliation(s)
- Manuel Matzinger
- Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Vienna, Austria.
| | - Adrian Vasiu
- Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Vienna, Austria
| | - Mathias Madalinski
- Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Vienna, Austria
| | - Fränze Müller
- Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Vienna, Austria
| | - Florian Stanek
- Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Vienna, Austria
| | - Karl Mechtler
- Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Vienna, Austria. .,Institute of Molecular Biotechnology, Austrian Academy of Sciences, Vienna BioCenter (VBC), Vienna, Austria.
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4
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Graziadei A, Rappsilber J. Leveraging crosslinking mass spectrometry in structural and cell biology. Structure 2021; 30:37-54. [PMID: 34895473 DOI: 10.1016/j.str.2021.11.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 10/11/2021] [Accepted: 11/17/2021] [Indexed: 12/18/2022]
Abstract
Crosslinking mass spectrometry (crosslinking-MS) is a versatile tool providing structural insights into protein conformation and protein-protein interactions. Its medium-resolution residue-residue distance restraints have been used to validate protein structures proposed by other methods and have helped derive models of protein complexes by integrative structural biology approaches. The use of crosslinking-MS in integrative approaches is underpinned by progress in estimating error rates in crosslinking-MS data and in combining these data with other information. The flexible and high-throughput nature of crosslinking-MS has allowed it to complement the ongoing resolution revolution in electron microscopy by providing system-wide residue-residue distance restraints, especially for flexible regions or systems. Here, we review how crosslinking-MS information has been leveraged in structural model validation and integrative modeling. Crosslinking-MS has also been a key technology for cell biology studies and structural systems biology where, in conjunction with cryoelectron tomography, it can provide structural and mechanistic insights directly in situ.
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Affiliation(s)
- Andrea Graziadei
- Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, 13355 Berlin, Germany
| | - Juri Rappsilber
- Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, 13355 Berlin, Germany; Wellcome Centre for Cell Biology, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, UK.
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5
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Piersimoni L, Kastritis PL, Arlt C, Sinz A. Cross-Linking Mass Spectrometry for Investigating Protein Conformations and Protein-Protein Interactions─A Method for All Seasons. Chem Rev 2021; 122:7500-7531. [PMID: 34797068 DOI: 10.1021/acs.chemrev.1c00786] [Citation(s) in RCA: 106] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Mass spectrometry (MS) has become one of the key technologies of structural biology. In this review, the contributions of chemical cross-linking combined with mass spectrometry (XL-MS) for studying three-dimensional structures of proteins and for investigating protein-protein interactions are outlined. We summarize the most important cross-linking reagents, software tools, and XL-MS workflows and highlight prominent examples for characterizing proteins, their assemblies, and interaction networks in vitro and in vivo. Computational modeling plays a crucial role in deriving 3D-structural information from XL-MS data. Integrating XL-MS with other techniques of structural biology, such as cryo-electron microscopy, has been successful in addressing biological questions that to date could not be answered. XL-MS is therefore expected to play an increasingly important role in structural biology in the future.
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Affiliation(s)
- Lolita Piersimoni
- Department of Pharmaceutical Chemistry & Bioanalytics, Institute of Pharmacy, Kurt-Mothes-Strasse 3, D-06120 Halle (Saale), Germany.,Center for Structural Mass Spectrometry, Kurt-Mothes-Strasse 3, D-06120 Halle (Saale), Germany
| | - Panagiotis L Kastritis
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Kurt-Mothes-Strasse 3a, D-06120 Halle (Saale), Germany.,Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Strasse 3, D-06120 Halle (Saale), Germany.,Biozentrum, Weinbergweg 22, D-06120 Halle (Saale), Germany
| | - Christian Arlt
- Department of Pharmaceutical Chemistry & Bioanalytics, Institute of Pharmacy, Kurt-Mothes-Strasse 3, D-06120 Halle (Saale), Germany.,Center for Structural Mass Spectrometry, Kurt-Mothes-Strasse 3, D-06120 Halle (Saale), Germany
| | - Andrea Sinz
- Department of Pharmaceutical Chemistry & Bioanalytics, Institute of Pharmacy, Kurt-Mothes-Strasse 3, D-06120 Halle (Saale), Germany.,Center for Structural Mass Spectrometry, Kurt-Mothes-Strasse 3, D-06120 Halle (Saale), Germany
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Yugandhar K, Zhao Q, Gupta S, Xiong D, Yu H. Progress in methodologies and quality-control strategies in protein cross-linking mass spectrometry. Proteomics 2021; 21:e2100145. [PMID: 34647422 DOI: 10.1002/pmic.202100145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 10/04/2021] [Indexed: 11/10/2022]
Abstract
Deciphering the interaction networks and structural dynamics of proteins is pivotal to better understanding their biological functions. Cross-linking mass spectrometry (XL-MS) is a powerful and increasingly popular technology that provides information about protein-protein interactions and their structural constraints for individual proteins and multiprotein complexes on a proteome-scale. In this review, we first assess the coverage and depth of the XL-MS technique by utilizing publicly available datasets. We then delve into the progress in XL-MS experimental and computational methodologies and examine different quality-control strategies reported in the literature. Finally, we discuss the progress in XL-MS applications along with the scope for future improvements.
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Affiliation(s)
- Kumar Yugandhar
- Department of Computational Biology, Cornell University, New York, USA.,Weill Institute for Cell and Molecular Biology, Cornell University, New York, USA
| | - Qiuye Zhao
- Department of Computational Biology, Cornell University, New York, USA.,Weill Institute for Cell and Molecular Biology, Cornell University, New York, USA
| | - Shobhita Gupta
- Department of Computational Biology, Cornell University, New York, USA.,Weill Institute for Cell and Molecular Biology, Cornell University, New York, USA
| | - Dapeng Xiong
- Department of Computational Biology, Cornell University, New York, USA.,Weill Institute for Cell and Molecular Biology, Cornell University, New York, USA
| | - Haiyuan Yu
- Department of Computational Biology, Cornell University, New York, USA.,Weill Institute for Cell and Molecular Biology, Cornell University, New York, USA
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de Jong L, Roseboom W, Kramer G. Towards low false discovery rate estimation for protein-protein interactions detected by chemical cross-linking. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2021; 1869:140655. [PMID: 33812047 DOI: 10.1016/j.bbapap.2021.140655] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 03/28/2021] [Accepted: 03/29/2021] [Indexed: 01/16/2023]
Abstract
Chemical cross-linking (CX) of proteins in vivo or in cell free extracts followed by mass spectrometric (MS) identification of linked peptide pairs (CXMS) can reveal protein-protein interactions (PPIs) both at a proteome wide scale and the level of cross-linked amino acid residues. However, error estimation at the level of PPI remains challenging in large scale datasets. Here we discuss recent advances in the recognition of spurious inter-protein peptide pairs and in diminishing the FDR for these PPI-signaling cross-links, such as the use of chromatographic retention time prediction, in order to come to a more reliable reporting of PPIs.
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Affiliation(s)
- Luitzen de Jong
- Swammerdam Institute for Life Sciences, Mass Spectrometry of Biomolecules, University of Amsterdam, Science Park 904, 1098 HX Amsterdam, the Netherlands.
| | - Winfried Roseboom
- Swammerdam Institute for Life Sciences, Mass Spectrometry of Biomolecules, University of Amsterdam, Science Park 904, 1098 HX Amsterdam, the Netherlands
| | - Gertjan Kramer
- Swammerdam Institute for Life Sciences, Mass Spectrometry of Biomolecules, University of Amsterdam, Science Park 904, 1098 HX Amsterdam, the Netherlands
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