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Liew JJM, Wicht DK, Gonzalez R, Dowling DP, Ellis HR. Current understanding of enzyme structure and function in bacterial two-component flavin-dependent desulfonases: Cleaving C-S bonds of organosulfur compounds. Arch Biochem Biophys 2024; 758:110048. [PMID: 38848996 DOI: 10.1016/j.abb.2024.110048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 06/03/2024] [Accepted: 06/04/2024] [Indexed: 06/09/2024]
Abstract
The inherent structural properties of enzymes are critical in defining catalytic function. Often, studies to evaluate the relationship between structure and function are limited to only one defined structural element. The two-component flavin-dependent desulfonase family of enzymes involved in bacterial sulfur acquisition utilize a comprehensive range of structural features to carry out the desulfonation of organosulfur compounds. These metabolically essential two-component FMN-dependent desulfonase systems have been proposed to utilize oligomeric changes, protein-protein interactions for flavin transfer, and common mechanistic steps for carbon-sulfur bond cleavage. This review is focused on our current functional and structural understanding of two-component FMN-dependent desulfonase systems from multiple bacterial sources. Mechanistic and structural comparisons from recent independent studies provide fresh insights into the overall functional properties of these systems and note areas in need of further investigation. The review acknowledges current studies focused on evaluating the structural properties of these enzymes in relationship to their distinct catalytic function. The role of these enzymes in maintaining adequate sulfur levels, coupled with the conserved nature of these enzymes in diverse bacteria, underscore the importance in understanding the functional and structural nuances of these systems.
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Affiliation(s)
- Jeremy J M Liew
- Department of Chemistry, University of Massachusetts Boston, Boston, MA, 02125, USA
| | - Denyce K Wicht
- Department of Biochemistry, Chemistry, Environment, and Physics, Suffolk University, Boston, MA, 02108, USA
| | - Reyaz Gonzalez
- Department of Chemistry, University of Massachusetts Boston, Boston, MA, 02125, USA
| | - Daniel P Dowling
- Department of Chemistry, University of Massachusetts Boston, Boston, MA, 02125, USA
| | - Holly R Ellis
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University, Greenville, NC, 27834, USA.
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2
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Jiang T, Wan G, Zhang H, Gyawali YP, Underbakke ES, Feng C. Mapping the Intersubunit Interdomain FMN-Heme Interactions in Neuronal Nitric Oxide Synthase by Targeted Quantitative Cross-Linking Mass Spectrometry. Biochemistry 2024; 63:1395-1411. [PMID: 38747545 DOI: 10.1021/acs.biochem.4c00157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Nitric oxide synthase (NOS) in mammals is a family of multidomain proteins in which interdomain electron transfer (IET) is controlled by domain-domain interactions. Calmodulin (CaM) binds to the canonical CaM-binding site in the linker region between the FMN and heme domains of NOS and allows tethered FMN domain motions, enabling an intersubunit FMN-heme IET in the output state for NO production. Our previous cross-linking mass spectrometric (XL MS) results demonstrated site-specific protein dynamics in the CaM-responsive regions of rat neuronal NOS (nNOS) reductase construct, a monomeric protein [Jiang et al., Biochemistry, 2023, 62, 2232-2237]. In this work, we have extended our combined approach of XL MS structural mapping and AlphaFold structural prediction to examine the homodimeric nNOS oxygenase/FMN (oxyFMN) construct, an established model of the NOS output state. We employed parallel reaction monitoring (PRM) based quantitative XL MS (qXL MS) to assess the CaM-induced changes in interdomain dynamics and interactions. Intersubunit cross-links were identified by mapping the cross-links onto top AlphaFold structural models, which was complemented by comparing their relative abundances in the cross-linked dimeric and monomeric bands. Furthermore, contrasting the CaM-free and CaM-bound nNOS samples shows that CaM enables the formation of the intersubunit FMN-heme docking complex and that CaM binding induces extensive, allosteric conformational changes across the NOS regions. Moreover, the observed cross-links sites specifically respond to changes in ionic strength. This indicates that interdomain salt bridges are responsible for stabilizing and orienting the output state for efficient FMN-heme IET. Taken together, our targeted qXL MS results have revealed that CaM and ionic strength modulate specific dynamic changes in the CaM/FMN/heme complexes, particularly in the context of intersubunit interdomain FMN-heme interactions.
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Affiliation(s)
- Ting Jiang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Guanghua Wan
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Haikun Zhang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Yadav Prasad Gyawali
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Eric S Underbakke
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, United States
| | - Changjian Feng
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, New Mexico 87131, United States
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
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3
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Rossi M, Tomaselli F, Hochkoeppler A. The four subunits of rabbit skeletal muscle lactate dehydrogenase do not exert their catalytic action additively. Biochem Biophys Res Commun 2024; 690:149294. [PMID: 38011772 DOI: 10.1016/j.bbrc.2023.149294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Accepted: 11/17/2023] [Indexed: 11/29/2023]
Abstract
Oligomeric enzymes containing multiple active sites are usually considered to perform their catalytic action at higher rates when compared with their monomeric counterparts. This implies, in turn, that the activity performed by different holoenzyme subunits features additivity. Nevertheless, the extent of this additivity occurring in holoenzymes is far from being adequately understood. To tackle this point, we used tetrameric rabbit lactate dehydrogenase (rbLDH) as a model system to assay the reduction of pyruvate catalysed by this enzyme at the expense of β-NADH under pre-steady-state conditions. In particular, we observed the kinetics of reactions triggered by concentrations of β-NADH equimolar to 1, 2, 3, or all 4 subunits of the rbLDH holoenzyme, in the presence of an excess of pyruvate. Surprisingly, when the concentration of the limiting reactant exceeded that of a single holoenzyme subunit, we observed a sharp slowdown of the enzyme conformational rearrangements associated to the generation and the release of l-lactate. Furthermore, using a model to interpret the complex kinetics observed under the highest concentration of the limiting reactant, we estimated the diversity of the rates describing the action of the different rbLDH subunits.
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Affiliation(s)
- Martina Rossi
- Department of Pharmacy and Biotechnology, University of Bologna, Viale Risorgimento 4, 40136, Bologna, Italy
| | - Fabio Tomaselli
- Department of Pharmacy and Biotechnology, University of Bologna, Viale Risorgimento 4, 40136, Bologna, Italy
| | - Alejandro Hochkoeppler
- Department of Pharmacy and Biotechnology, University of Bologna, Viale Risorgimento 4, 40136, Bologna, Italy; CSGI, University of Firenze, Via della Lastruccia 3, 50019, Sesto Fiorentino, FI, Italy.
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4
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Huang W, Chen W, Chen Y, Fang S, Huang T, Chang P, Chang Y. Salmonella YqiC exerts its function through an oligomeric state. Protein Sci 2023; 32:e4749. [PMID: 37555831 PMCID: PMC10503411 DOI: 10.1002/pro.4749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 07/18/2023] [Accepted: 08/07/2023] [Indexed: 08/10/2023]
Abstract
Protein oligomerization occurs frequently both in vitro and in vivo, with specific functionalities associated with different oligomeric states. The YqiC protein from Salmonella Typhimurium forms a homotrimer through its C-terminal coiled-coil domain, and the protein is closely linked to the colonization and invasion of the bacteria to the host cells. To elucidate the importance of the oligomeric state of YqiC in vivo and its relation with bacterial infection, we mutated crucial residues in YqiC's coiled-coil region and confirmed the loss of trimer formation using chemical crosslinking and size exclusion chromatography coupled with multiple angle light scattering (SEC-MALS) techniques. The yqiC-knockout strain complemented with mutant YqiC showed significantly reduced colonization and invasion of Salmonella to host cells, demonstrating the critical role of YqiC oligomerization in bacterial pathogenesis. Furthermore, we conducted a protein-protein interaction study of YqiC using a pulled-down assay coupled with mass spectrometry analysis to investigate the protein's role in bacterial virulence. The results reveal that YqiC interacts with subunits of Complex II of the electron transport chain (SdhA and SdhB) and the β-subunit of F0 F1 -ATP synthase. These interactions suggest that YqiC may modulate the energy production of Salmonella and subsequently affect the assembly of crucial virulence factors, such as flagella. Overall, our findings provide new insights into the molecular mechanisms of YqiC's role in S. Typhimurium pathogenesis and suggest potential therapeutic targets for bacterial infections.
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Affiliation(s)
- Wei‐Chun Huang
- Department of Biochemistry and Molecular Cell Biology, School of Medicine, College of MedicineTaipei Medical UniversityTaipeiTaiwan
| | - Wai‐Ting Chen
- Department of Biochemistry and Molecular Cell Biology, School of Medicine, College of MedicineTaipei Medical UniversityTaipeiTaiwan
| | - Yueh‐Chen Chen
- Department of Biochemistry and Molecular Cell Biology, School of Medicine, College of MedicineTaipei Medical UniversityTaipeiTaiwan
| | - Shiuh‐Bin Fang
- Division of Pediatric Gastroenterology and Hepatology, Department of Pediatrics, Shuang Ho HospitalTaipei Medical UniversityTaipeiTaiwan
- Department of Pediatrics, School of Medicine, College of MedicineTaipei Medical UniversityTaipeiTaiwan
- Master Program for Clinical Genomics and Proteomics, College of PharmacyTaipei Medical UniversityTaipeiTaiwan
| | - Tzu‐Wen Huang
- Department of Microbiology and Immunology, School of Medicine, College of MedicineTaipei Medical UniversityTaipeiTaiwan
| | - Pei‐Ru Chang
- Division of Pediatric Gastroenterology and Hepatology, Department of Pediatrics, Shuang Ho HospitalTaipei Medical UniversityTaipeiTaiwan
- Department of Pediatrics, School of Medicine, College of MedicineTaipei Medical UniversityTaipeiTaiwan
| | - Yu‐Chu Chang
- Department of Biochemistry and Molecular Cell Biology, School of Medicine, College of MedicineTaipei Medical UniversityTaipeiTaiwan
- Graduate Institute of Medical Sciences, College of MedicineTaipei Medical UniversityTaipeiTaiwan
- International PhD Program in Cell Therapy and Regenerative Medicine, College of MedicineTaipei Medical UniversityTaipeiTaiwan
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5
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Townsend JA, Marty MT. What's the defect? Using mass defects to study oligomerization of membrane proteins and peptides in nanodiscs with native mass spectrometry. Methods 2023; 218:1-13. [PMID: 37482149 PMCID: PMC10529358 DOI: 10.1016/j.ymeth.2023.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 06/20/2023] [Accepted: 07/03/2023] [Indexed: 07/25/2023] Open
Abstract
Many membrane proteins form functional complexes that are either homo- or hetero-oligomeric. However, it is challenging to characterize membrane protein oligomerization in intact lipid bilayers, especially for polydisperse mixtures. Native mass spectrometry of membrane proteins and peptides inserted in lipid nanodiscs provides a unique method to study the oligomeric state distribution and lipid preferences of oligomeric assemblies. To interpret these complex spectra, we developed novel data analysis methods using macromolecular mass defect analysis. Here, we provide an overview of how mass defect analysis can be used to study oligomerization in nanodiscs, discuss potential limitations in interpretation, and explore strategies to resolve these ambiguities. Finally, we review recent work applying this technique to studying formation of antimicrobial peptide, amyloid protein, and viroporin complexes with lipid membranes.
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Affiliation(s)
- Julia A Townsend
- Department of Chemistry and Biochemistry and Bio5 Institute, University of Arizona, Tucson, AZ 85721, USA
| | - Michael T Marty
- Department of Chemistry and Biochemistry and Bio5 Institute, University of Arizona, Tucson, AZ 85721, USA.
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6
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Aloh CH, Zeczycki TN, Ellis HR. Oligomeric Changes Regulate Flavin Transfer in Two-Component FMN Reductases Involved in Sulfur Metabolism. Biochemistry 2023; 62:2751-2762. [PMID: 37651343 DOI: 10.1021/acs.biochem.3c00361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
The FMN reductases (SsuE and MsuE of the alkanesulfonate monooxygenase systems) supply reduced flavin to their partner monooxygenases for the desulfonation of alkanesulfonates. Flavin reductases that comprise two-component systems must be able to regulate both flavin reduction and transfer. One mechanism to control these distinct processes is through changes in the oligomeric state of the enzymes. Despite their similar overall structures, SsuE and MsuE showed clear differences in their oligomeric states in the presence of substrates. The oligomeric state of SsuE was converted from a tetramer to a dimer/tetramer equilibrium in the presence of FMN or NADPH in analytical ultracentrifugation studies. Conversely, MsuE shifted from a dimer to a single tetrameric state with FMN, and the NADPH substrate did not induce a similar oligomeric shift. There was a fast tetramer to dimer equilibrium shift occurring at the dimer/dimer interface in H/D-X investigations with apo SsuE. Formation of the SsuE/FMN complex slowed the tetramer/dimer conversion, leading to a slower exchange along the dimer/dimer interface. The oligomeric shift of the MsuE/FMN complex from a dimer to a distinct tetramer showed a decrease in H/D-X in the region around the π-helices at the dimer/dimer interface. Both SsuE and MsuE showed a comparable and significant increase in the melting temperature with the addition of FMN, indicating the conformers formed by each FMN-bound enzyme had increased stability. A mechanism that supports the different structural shifts is rationalized by the different roles these enzymes play in providing reduced flavin to single or multiple monooxygenase enzymes.
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Affiliation(s)
- Chioma H Aloh
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University, Greenville, North Carolina 27834, United States
| | - Tonya N Zeczycki
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University, Greenville, North Carolina 27834, United States
| | - Holly R Ellis
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University, Greenville, North Carolina 27834, United States
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7
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McElroy C, Ihms E, Yadav DK, Holmquist M, Wadwha V, Wysocki V, Gollnick P, Foster M. Solution structure, dynamics and tetrahedral assembly of Anti-TRAP, a homo-trimeric triskelion-shaped regulator of tryptophan biosynthesis in Bacillus subtilis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.29.547145. [PMID: 37425951 PMCID: PMC10327191 DOI: 10.1101/2023.06.29.547145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Cellular production of tryptophan is metabolically expensive and tightly regulated. The small Bacillus subtilis zinc binding Anti-TRAP protein (AT), which is the product of the yczA/rtpA gene, is upregulated in response to accumulating levels of uncharged tRNATrp through a T-box antitermination mechanism. AT binds to the undecameric ring-shaped protein TRAP (trp RNA Binding Attenuation Protein), thereby preventing it from binding to the trp leader RNA. This reverses the inhibitory effect of TRAP on transcription and translation of the trp operon. AT principally adopts two symmetric oligomeric states, a trimer (AT3) featuring a three-helix bundle, or a dodecamer (AT12) comprising a tetrahedral assembly of trimers, whereas only the trimeric form has been shown to bind and inhibit TRAP. We demonstrate the utility of native mass spectrometry (nMS) and small-angle x-ray scattering (SAXS), together with analytical ultracentrifugation (AUC) for monitoring the pH and concentration-dependent equilibrium between the trimeric and dodecameric structural forms of AT. In addition, we report the use of solution nuclear magnetic resonance (NMR) spectroscopy to determine the solution structure of AT3, while heteronuclear 15N relaxation measurements on both oligomeric forms of AT provide insights into the dynamic properties of binding-active AT3 and binding-inactive AT12, with implications for TRAP inhibition.
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Affiliation(s)
- Craig McElroy
- Ohio State Biochemistry Program
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
| | - Elihu Ihms
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
- Biophysics Program
| | - Deepak Kumar Yadav
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
| | - Melody Holmquist
- Ohio State Biochemistry Program
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
| | - Vibhuti Wadwha
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
| | - Vicki Wysocki
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
- National Resource for Native MS-Guided Structural Biology
| | - Paul Gollnick
- Department of Biological Sciences, State University of New York, Buffalo NY 14260
| | - Mark Foster
- Ohio State Biochemistry Program
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
- Biophysics Program
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8
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Bu W, Levitskaya Z, Tan SM, Gao YG. Emerging evidence for kindlin oligomerization and its role in regulating kindlin function. J Cell Sci 2021; 134:256567. [PMID: 33912917 DOI: 10.1242/jcs.256115] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Integrin-mediated cell-extracellular matrix (ECM) interactions play crucial roles in a broad range of physiological and pathological processes. Kindlins are important positive regulators of integrin activation. The FERM-domain-containing kindlin family comprises three members, kindlin-1, kindlin-2 and kindlin-3 (also known as FERMT1, FERMT2 and FERMT3), which share high sequence similarity (identity >50%), as well as domain organization, but exhibit diverse tissue-specific expression patterns and cellular functions. Given the significance of kindlins, analysis of their atomic structures has been an attractive field for decades. Recently, the structures of kindlin and its β-integrin-bound form have been obtained, which greatly advance our understanding of the molecular functions that involve kindlins. In particular, emerging evidence indicates that oligomerization of kindlins might affect their integrin binding and focal adhesion localization, positively or negatively. In this Review, we presented an update on the recent progress of obtaining kindlin structures, and discuss the implication for integrin activation based on kindlin oligomerization, as well as the possible regulation of this process.
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Affiliation(s)
- Wenting Bu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore637551.,Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China518055
| | - Zarina Levitskaya
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore637551
| | - Suet-Mien Tan
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore637551
| | - Yong-Gui Gao
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore637551.,NTU Institute of Structural Biology, Nanyang Technological University, 59 Nanyang Drive, Singapore639798
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9
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Ghanbarpour A, Santos EM, Pinger C, Assar Z, Hossaini Nasr S, Vasileiou C, Spence D, Borhan B, Geiger JH. Human Cellular Retinol Binding Protein II Forms a Domain-Swapped Trimer Representing a Novel Fold and a New Template for Protein Engineering. Chembiochem 2020; 21:3192-3196. [PMID: 32608180 PMCID: PMC8220890 DOI: 10.1002/cbic.202000405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 06/29/2020] [Indexed: 11/07/2022]
Abstract
Domain-swapping is a mechanism for evolving new protein structure from extant scaffolds, and has been an efficient protein-engineering strategy for tailoring functional diversity. However, domain swapping can only be exploited if it can be controlled, especially in cases where various folds can coexist. Herein, we describe the structure of a domain-swapped trimer of the iLBP family member hCRBPII, and suggest a mechanism for domain-swapped trimerization. It is further shown that domain-swapped trimerization can be favored by strategic installation of a disulfide bond, thus demonstrating a strategy for fold control. We further show the domain-swapped trimer to be a useful protein design template by installing a high-affinity metal binding site through the introduction of a single mutation, taking advantage of its threefold symmetry. Together, these studies show how nature can promote oligomerization, stabilize a specific oligomer, and generate new function with minimal changes to the protein sequence.
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Affiliation(s)
- Alireza Ghanbarpour
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA
- Yale University Medical School, Department of Cell Biology, 333 S. Cedar Street, New Haven, CT 06510, USA
| | - Elizabeth M Santos
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA
- Dow Performance Silicones, 2200W Salzburg Road, Midland, MI 48686, USA
| | - Cody Pinger
- Department of Biomedical Engineering, Michigan State University, 775 Woodlot Drive, East Lansing, MI 48823, USA
| | - Zahra Assar
- Cayman Chemical, 1180 East Ellsworth Road, Ann Arbor, MI 48108, USA
| | - Seyedmehdi Hossaini Nasr
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA
| | - Chrysoula Vasileiou
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA
| | - Dana Spence
- Department of Biomedical Engineering, Michigan State University, 775 Woodlot Drive, East Lansing, MI 48823, USA
| | - Babak Borhan
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA
| | - James H Geiger
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, MI 48824, USA
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Koch D. Homo-Oligomerisation in Signal Transduction: Dynamics, Homeostasis, Ultrasensitivity, Bistability. J Theor Biol 2020; 499:110305. [PMID: 32437710 PMCID: PMC7327509 DOI: 10.1016/j.jtbi.2020.110305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 04/26/2020] [Accepted: 04/27/2020] [Indexed: 01/08/2023]
Abstract
Homo-oligomerisation may offer an unexpected variety of signal processing functions. These include: dynamic signal encoding via oligomeric complex size. Homeostatic regulation of monomer concentration. Bistability via pseudo-multisite modification and multi-enzyme regulation. The findings partly explain why homo-oligomerisation is so commonly found in evolution.
Homo-oligomerisation of proteins is a ubiquitous phenomenon whose exact role remains unclear in many cases. To identify novel functions, this paper provides an exploration of general dynamical mathematical models of homo-oligomerisation. Simulation and analysis of these models show that homo-oligomerisation on its own allows for a remarkable variety of complex dynamic and steady state regulatory behaviour such as transient overshoots or homeostatic control of monomer concentration. If post-translational modifications are considered, however, conventional mass action kinetics lead to thermodynamic inconsistencies due to asymmetric combinatorial expansion of reaction routes. Introducing a conservation principle to balance rate equations re-establishes thermodynamic consistency. Using such balanced models it is shown that oligomerisation can lead to bistability by enabling pseudo-multisite modification and kinetic pseudo-cooperativity via multi-enzyme regulation, thereby constituting a novel motif for bistable modification reactions. Due to these potential signal processing capabilities, homo-oligomerisation could play far more versatile roles in signal transduction than previously appreciated.
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Affiliation(s)
- Daniel Koch
- Randall Centre for Cell & Molecular Biophysics King's College London, London SE1 1UL, United Kingdom.
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