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Richardson-Sanchez T, Chan ACK, Sabatino B, Lin H, Gaynor EC, Murphy MEP. Dissecting components of the Campylobacter jejuni fetMP-fetABCDEF gene cluster under iron limitation. Microbiol Spectr 2024; 12:e0314823. [PMID: 38096459 PMCID: PMC10783030 DOI: 10.1128/spectrum.03148-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 11/14/2023] [Indexed: 12/26/2023] Open
Abstract
IMPORTANCE Campylobacter jejuni is a bacterium that is prevalent in the ceca of farmed poultry such as chickens. Consumption of ill-prepared poultry is thus the most common route by which C. jejuni infects the human gut to cause a typically self-limiting but severe gastrointestinal illness that can be fatal to very young, old, or immunocompromised people. The lack of a vaccine and an increasing resistance to current antibiotics highlight a need to better understand the mechanisms that make C. jejuni a successful human pathogen. This study focused on the functional components of one such mechanism-a molecular system that helps C. jejuni thrive despite the restriction on growth-available iron by the human body, which typically defends against pathogens. In providing a deeper understanding of how this system functions, this study contributes toward the goal of reducing the enormous global socioeconomic burden caused by C. jejuni.
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Affiliation(s)
- Tomas Richardson-Sanchez
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Anson C. K. Chan
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Brendil Sabatino
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Helen Lin
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Erin C. Gaynor
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Michael E. P. Murphy
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada
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2
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Onda Y, Okino T. Thiol-disulfide oxidoreductase PDI1;1 regulates actin structures in Oryza sativa root cells. FEBS Lett 2022; 596:3015-3023. [PMID: 35781879 DOI: 10.1002/1873-3468.14445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 06/20/2022] [Accepted: 06/21/2022] [Indexed: 12/14/2022]
Abstract
The polarized and dynamic actin cytoskeleton is essential for root cell growth. Here, we report the key role of thiol-disulfide oxidoreductase PDI1;1 in actin structures. Microscopic analyses revealed that after Oryza sativa roots were exposed to H2 O2 , both actin and PDI1;1 were depolarized and arranged in a meshwork. In H2 O2 -exposed cells, actin formed intermolecularly disulfide-bonded high-molecular-weight structures, which were thiol-trapped by PDI1;1. Recombinant PDI1;1 exhibited the ability to recognize actin in an in vitro binding assay. During recovery from H2 O2 exposure, the amount of disulfide-bonded high-molecular-weight structures of actin decreased over time, but deficiency of PDI1;1 inhibited the decrease. These results suggest a PDI1;1-dependent pathway that reduces disulfide bonds in high-molecular-weight structures of actin, thus promoting their degradation.
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Affiliation(s)
- Yayoi Onda
- Graduate School of Agriculture, Ehime University, Matsuyama, Japan
| | - Tomoya Okino
- Faculty of Agriculture, Ehime University, Matsuyama, Japan
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3
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Lee SF, Li L, Jalal N, Halperin SA. Identification of a Thiol-Disulfide Oxidoreductase (SdbA) Catalyzing Disulfide Bond Formation in the Superantigen SpeA in Streptococcus pyogenes. J Bacteriol 2021; 203:e0015321. [PMID: 34152832 DOI: 10.1128/JB.00153-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mechanisms of disulfide bond formation in the human pathogen Streptococcus pyogenes are currently unknown. To date, no disulfide bond-forming thiol-disulfide oxidoreductase (TDOR) has been described and at least one disulfide bonded protein is known in S. pyogenes. This protein is the superantigen SpeA, which contains 3 cysteine residues (Cys 87, Cys90, and Cys98) and has a disulfide bond formed between Cys87 and Cys98. In this study, candidate TDORs were identified from the genome sequence of S. pyogenes MGAS8232. Using mutational and biochemical approaches, one of the candidate proteins, SpyM18_2037 (named here SdbA), was shown to be the catalyst that introduces the disulfide bond in SpeA. SpeA in the culture supernatant remained reduced when sdbA was inactivated and restored to the oxidized state when a functional copy of sdbA was returned to the sdbA-knockout mutant. SdbA has a typical C46XXC49 active site motif commonly found in TDORs. Site-directed mutagenesis experiments showed that the cysteines in the CXXC motif were required for the disulfide bond in SpeA to form. Interactions between SdbA and SpeA were examined using cysteine variant proteins. The results showed that SdbAC49A formed a mixed disulfide with SpeAC87A, suggesting that the N-terminal Cys46 of SdbA and the C-terminal Cys98 of SpeA participated in the initial reaction. SpeA oxidized by SdbA displayed biological activities suggesting that SpeA was properly folded following oxidation by SdbA. In conclusion, formation of the disulfide bond in SpeA is catalyzed by SdbA and the findings represent the first report of disulfide bond formation in S. pyogenes. IMPORTANCE Here, we reported the first example of disulfide bond formation in Streptococcus pyogenes. The results showed that a thiol-disulfide oxidoreductase, named SdbA, is responsible for introducing the disulfide bond in the superantigen SpeA. The cysteine residues in the CXXC motif of SdbA are needed for catalyzing the disulfide bond in SpeA. The disulfide bond in SpeA and neighboring amino acids form a disulfide loop that is conserved among many superantigens, including those from Staphylococcus aureus. SpeA and staphylococcal enterotoxins lacking the disulfide bond are biologically inactive. Thus, the discovery of the enzyme that catalyzes the disulfide bond in SpeA is important for understanding the biochemistry of SpeA production and presents a target for mitigating the virulence of S. pyogenes.
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Nilewski S, Varatnitskaya M, Masuch T, Kusnezowa A, Gellert M, Baumann AF, Lupilov N, Kusnezow W, Koch MH, Eisenacher M, Berkmen M, Lillig CH, Leichert LI. Functional metagenomics of the thioredoxin superfamily. J Biol Chem 2021; 296:100247. [PMID: 33361108 PMCID: PMC7949104 DOI: 10.1074/jbc.ra120.016350] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/18/2020] [Accepted: 12/24/2020] [Indexed: 11/06/2022] Open
Abstract
Environmental sequence data of microbial communities now makes up the majority of public genomic information. The assignment of a function to sequences from these metagenomic sources is challenging because organisms associated with the data are often uncharacterized and not cultivable. To overcome these challenges, we created a rationally designed expression library of metagenomic proteins covering the sequence space of the thioredoxin superfamily. This library of 100 individual proteins represents more than 22,000 thioredoxins found in the Global Ocean Sampling data set. We screened this library for the functional rescue of Escherichia coli mutants lacking the thioredoxin-type reductase (ΔtrxA), isomerase (ΔdsbC), or oxidase (ΔdsbA). We were able to assign functions to more than a quarter of our representative proteins. The in vivo function of a given representative could not be predicted by phylogenetic relation but did correlate with the predicted isoelectric surface potential of the protein. Selected proteins were then purified, and we determined their activity using a standard insulin reduction assay and measured their redox potential. An unexpected gel shift of protein E5 during the redox potential determination revealed a redox cycle distinct from that of typical thioredoxin-superfamily oxidoreductases. Instead of the intramolecular disulfide bond formation typical for thioredoxins, this protein forms an intermolecular disulfide between the attacking cysteines of two separate subunits during its catalytic cycle. Our functional metagenomic approach proved not only useful to assign in vivo functions to representatives of thousands of proteins but also uncovered a novel reaction mechanism in a seemingly well-known protein superfamily.
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Affiliation(s)
- Sebastian Nilewski
- Institute of Biochemistry and Pathobiochemistry - Microbial Biochemistry, Ruhr-Universität Bochum, Bochum, Germany
| | - Marharyta Varatnitskaya
- Institute of Biochemistry and Pathobiochemistry - Microbial Biochemistry, Ruhr-Universität Bochum, Bochum, Germany
| | - Thorsten Masuch
- Institute of Biochemistry and Pathobiochemistry - Microbial Biochemistry, Ruhr-Universität Bochum, Bochum, Germany; Protein Expression and Modification Division, New England Biolabs, Ipswich, Massachusetts, USA
| | - Anna Kusnezowa
- Institute of Biochemistry and Pathobiochemistry - Microbial Biochemistry, Ruhr-Universität Bochum, Bochum, Germany
| | - Manuela Gellert
- Institute for Medical Biochemistry and Molecular Biology, Universität Greifswald, Greifswald, Germany
| | - Anne F Baumann
- Institute of Biochemistry and Pathobiochemistry - Microbial Biochemistry, Ruhr-Universität Bochum, Bochum, Germany
| | - Natalie Lupilov
- Institute of Biochemistry and Pathobiochemistry - Microbial Biochemistry, Ruhr-Universität Bochum, Bochum, Germany
| | - Witali Kusnezow
- Institute of Biochemistry and Pathobiochemistry - Microbial Biochemistry, Ruhr-Universität Bochum, Bochum, Germany
| | | | - Martin Eisenacher
- Medizinisches Proteom-Center, Ruhr-Universität Bochum, Bochum, Germany
| | - Mehmet Berkmen
- Protein Expression and Modification Division, New England Biolabs, Ipswich, Massachusetts, USA
| | - Christopher H Lillig
- Institute for Medical Biochemistry and Molecular Biology, Universität Greifswald, Greifswald, Germany
| | - Lars I Leichert
- Institute of Biochemistry and Pathobiochemistry - Microbial Biochemistry, Ruhr-Universität Bochum, Bochum, Germany.
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5
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Pothion H, Jehan C, Tostivint H, Cartier D, Bucharles C, Falluel-Morel A, Boukhzar L, Anouar Y, Lihrmann I. Selenoprotein T: An Essential Oxidoreductase Serving as a Guardian of Endoplasmic Reticulum Homeostasis. Antioxid Redox Signal 2020; 33:1257-1275. [PMID: 32524825 DOI: 10.1089/ars.2019.7931] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Significance: Selenoproteins incorporate the essential nutrient selenium into their polypeptide chain. Seven members of this family reside in the endoplasmic reticulum (ER), the exact function of most of which is poorly understood. Especially, how ER-resident selenoproteins control the ER redox and ionic environment is largely unknown. Since alteration of ER function is observed in many diseases, the elucidation of the role of selenoproteins could enhance our understanding of the mechanisms involved in ER homeostasis. Recent Advances: Among selenoproteins, selenoprotein T (SELENOT) is remarkable as the most evolutionarily conserved and the only ER-resident selenoprotein whose gene knockout in mouse is lethal. Recent data indicate that SELENOT contributes to ER homeostasis: reduced expression of SELENOT in transgenic cell and animal models promotes accumulation of reactive oxygen and nitrogen species, depletion of calcium stores, activation of the unfolded protein response and impaired hormone secretion. Critical Issues: SELENOT is anchored to the ER membrane and associated with the oligosaccharyltransferase complex, suggesting that it regulates the early steps of N-glycosylation. Furthermore, it exerts a selenosulfide oxidoreductase activity carried by its thioredoxin-like domain. However, the physiological role of the redox activity of SELENOT is not fully understood. Likewise, the nature of its redox partners needs to be further characterized. Future Directions: Given the impact of ER stress in pathologies such as neurodegenerative, cardiovascular, metabolic and immune diseases, understanding the role of SELENOT and developing derived therapeutic tools such as selenopeptides to improve ER proteostasis and prevent ER stress could contribute to a better management of these diseases.
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Affiliation(s)
- Hugo Pothion
- Rouen-Normandie University, UNIROUEN, Inserm, U1239, Neuronal and Neuroendocrine Differentiation and Communication Laboratory, Mont-Saint-Aignan Cedex, France.,Institute for Research and Innovation in Biomedicine, Rouen, France
| | - Cédric Jehan
- Rouen-Normandie University, UNIROUEN, Inserm, U1239, Neuronal and Neuroendocrine Differentiation and Communication Laboratory, Mont-Saint-Aignan Cedex, France.,Institute for Research and Innovation in Biomedicine, Rouen, France
| | - Hervé Tostivint
- Physiologie moléculaire et Adaptation, UMR 7221 CNRS and Muséum National d'Histoire Naturelle, Paris, France
| | - Dorthe Cartier
- Rouen-Normandie University, UNIROUEN, Inserm, U1239, Neuronal and Neuroendocrine Differentiation and Communication Laboratory, Mont-Saint-Aignan Cedex, France.,Institute for Research and Innovation in Biomedicine, Rouen, France
| | - Christine Bucharles
- Rouen-Normandie University, UNIROUEN, Inserm, U1239, Neuronal and Neuroendocrine Differentiation and Communication Laboratory, Mont-Saint-Aignan Cedex, France.,Institute for Research and Innovation in Biomedicine, Rouen, France
| | - Anthony Falluel-Morel
- Rouen-Normandie University, UNIROUEN, Inserm, U1239, Neuronal and Neuroendocrine Differentiation and Communication Laboratory, Mont-Saint-Aignan Cedex, France.,Institute for Research and Innovation in Biomedicine, Rouen, France
| | - Loubna Boukhzar
- Rouen-Normandie University, UNIROUEN, Inserm, U1239, Neuronal and Neuroendocrine Differentiation and Communication Laboratory, Mont-Saint-Aignan Cedex, France.,Institute for Research and Innovation in Biomedicine, Rouen, France
| | - Youssef Anouar
- Rouen-Normandie University, UNIROUEN, Inserm, U1239, Neuronal and Neuroendocrine Differentiation and Communication Laboratory, Mont-Saint-Aignan Cedex, France.,Institute for Research and Innovation in Biomedicine, Rouen, France
| | - Isabelle Lihrmann
- Rouen-Normandie University, UNIROUEN, Inserm, U1239, Neuronal and Neuroendocrine Differentiation and Communication Laboratory, Mont-Saint-Aignan Cedex, France.,Institute for Research and Innovation in Biomedicine, Rouen, France
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6
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Lopez LC, Mukhitov N, Handley LD, Hamme CS, Hofman CR, Euers L, McKinney JR, Piers AD, Wadler E, Hunsicker-Wang LM. Characterization and effect of metal ions on the formation of the Thermus thermophilus Sco mixed disulfide intermediate. Protein Sci 2018; 27:1942-1954. [PMID: 30168216 DOI: 10.1002/pro.3502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Revised: 08/22/2018] [Accepted: 08/23/2018] [Indexed: 11/09/2022]
Abstract
The Sco protein from Thermus thermophilus has previously been shown to perform a disulfide bond reduction in the CuA protein from T. thermophilus, which is a soluble protein engineered from subunit II of cytochrome ba 3 oxidase that lacks the transmembrane helix. The native cysteines on TtSco and TtCuA were mutated to serine residues to probe the reactivities of the individual cysteines. Conjugation of TNB to the remaining cysteine in TtCuA and subsequent release upon incubation with the complementary TtSco protein demonstrated the formation of the mixed disulfide intermediate. The cysteine of TtSco that attacks the disulfide bond in the target TtCuA protein was determined to be TtSco Cysteine 49. This cysteine is likely more reactive than Cysteine 53 due to a higher degree of solvent exposure. Removal of the metal binding histidine, His 139, does not change MDI formation. However, altering the arginine adjacent to the reactive cysteine in Sco (Arginine 48) does alter the formation of the MDI. Binding of Cu2+ or Cu+ to TtSco prior to reaction with TtCuA was found to preclude formation of the mixed disulfide intermediate. These results shed light on a mechanism of disulfide bond reduction by the TtSco protein and may point to a possible role of metal binding in regulating the activity. IMPORTANCE: The function of Sco is at the center of many studies. The disulfide bond reduction in CuA by Sco is investigated herein and the effect of metal ions on the ability to reduce and form a mixed disulfide intermediate are also probed.
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Affiliation(s)
- Liezelle C Lopez
- Department of Chemistry, Trinity University, One Trinity Place, San Antonio, Texas, 78212-7200.,Baylor School of Medicine, One Baylor Plaza, Houston, Texas, 77030
| | - Nikita Mukhitov
- Department of Chemistry, Trinity University, One Trinity Place, San Antonio, Texas, 78212-7200.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139
| | - Lindsey D Handley
- Department of Chemistry, Trinity University, One Trinity Place, San Antonio, Texas, 78212-7200.,ThoughtSTEM, San Diego, California, 92108
| | - Cristina S Hamme
- Department of Chemistry, Trinity University, One Trinity Place, San Antonio, Texas, 78212-7200.,Lone Star Family Health Center, Conroe, Texas, 77034
| | - Cristina R Hofman
- Department of Chemistry, Trinity University, One Trinity Place, San Antonio, Texas, 78212-7200
| | - Lindsay Euers
- Department of Chemistry, Trinity University, One Trinity Place, San Antonio, Texas, 78212-7200.,Houston Methodist Hospital, Houston, Texas, 77303
| | - Jennifer R McKinney
- Department of Chemistry, Trinity University, One Trinity Place, San Antonio, Texas, 78212-7200.,Department of Maternal Fetal Medicine, Baylor College of Medicine, One Baylor Plaza, Houston, Texas, 77004
| | - Amani D Piers
- Department of Chemistry, Trinity University, One Trinity Place, San Antonio, Texas, 78212-7200.,Department of Psychology, Drexel University, Philadelphia, Pennsylvania, 19104
| | - Ellen Wadler
- Department of Chemistry, Trinity University, One Trinity Place, San Antonio, Texas, 78212-7200.,University of Texas Health Science Center Houston School of Public Health, Houston, Texas, 77030
| | - Laura M Hunsicker-Wang
- Department of Chemistry, Trinity University, One Trinity Place, San Antonio, Texas, 78212-7200
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Davey L, Halperin SA, Lee SF. Thiol-Disulfide Exchange in Gram-Positive Firmicutes. Trends Microbiol 2016; 24:902-915. [PMID: 27426970 DOI: 10.1016/j.tim.2016.06.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 06/08/2016] [Accepted: 06/28/2016] [Indexed: 11/17/2022]
Abstract
Extracytoplasmic thiol-disulfide oxidoreductases (TDORs) catalyze the oxidation, reduction, and isomerization of protein disulfide bonds. Although these processes have been characterized in Gram-negative bacteria, the majority of Gram-positive TDORs have only recently been discovered. Results from recent studies have revealed distinct trends in the types of TDOR used by different groups of Gram-positive bacteria, and in their biological functions. Actinobacteria TDORs can be essential for viability, while Firmicute TDORs influence various physiological processes, including protein stability, oxidative stress resistance, bacteriocin production, and virulence. In this review we discuss the diverse extracytoplasmic TDORs used by Gram-positive bacteria, with a focus on Gram-positive Firmicutes.
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Affiliation(s)
- Lauren Davey
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, B3H 1X5 Canada; Canadian Center for Vaccinology, Dalhousie University and the IWK Health Centre, Halifax, NS, B3K 6R8 Canada
| | - Scott A Halperin
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, B3H 1X5 Canada; Canadian Center for Vaccinology, Dalhousie University and the IWK Health Centre, Halifax, NS, B3K 6R8 Canada; Department of Pediatrics, Faculty of Medicine, Dalhousie University and the IWK Health Centre, Halifax, NS, B3K 6R8 Canada
| | - Song F Lee
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, B3H 1X5 Canada; Canadian Center for Vaccinology, Dalhousie University and the IWK Health Centre, Halifax, NS, B3K 6R8 Canada; Department of Pediatrics, Faculty of Medicine, Dalhousie University and the IWK Health Centre, Halifax, NS, B3K 6R8 Canada; Department of Applied Oral Sciences, Faculty of Dentistry, Dalhousie University, Halifax, NS, B3H 4R2 Canada.
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8
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Grosch M, Fuchs J, Bösl M, Winterpacht A, Tagariello A. Selenoprotein M is expressed during bone development. EXCLI J 2013; 12:967-79. [PMID: 27298612 PMCID: PMC4904744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Accepted: 11/04/2013] [Indexed: 10/29/2022]
Abstract
25 selenoproteins that contain selenium, incorporated as selenocysteine (Sec), have been identified to date. Selenoprotein M (SELM) is one of seven endoplasmic reticulum (ER)-resident, Sec-containing proteins that may be involved in posttranslational processing of proteins and maintenance of ER function. Since SELM was overrepresented in a cartilage- and bone-specific expressed sequence tag (EST) library, we further investigated the expression pattern of Selm and its possible biological function in the skeleton. RNA in situ hybridization of Selm in chicken and mice of different developmental stages revealed prominent expression in bones, specifically in osteoblast, and in tendons. This result suggests that SELM functions during bone development, where it is possibly involved in the processing of secreted proteins.
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Affiliation(s)
- Melanie Grosch
- Institute of Human Genetics, University Hospital Erlangen, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Jennifer Fuchs
- Institute of Human Genetics, University Hospital Erlangen, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Michael Bösl
- Max Planck Institute of Neurobiology, Martinsried, Germany
| | - Andreas Winterpacht
- Institute of Human Genetics, University Hospital Erlangen, University of Erlangen-Nürnberg, Erlangen, Germany,*To whom correspondence should be addressed: Andreas Winterpacht, Institute of Human Genetics, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg, Schwabachanlage 10, D-91054 Erlangen, Germany; Tel. ++49-9131-852-2019; FAX: ++49-9131-852-3232, E-mail:
| | - Andreas Tagariello
- Institute of Human Genetics, University Hospital Erlangen, University of Erlangen-Nürnberg, Erlangen, Germany
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9
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Colbert CL, Wu Q, Erbel PJA, Gardner KH, Deisenhofer J. Mechanism of substrate specificity in Bacillus subtilis ResA, a thioredoxin-like protein involved in cytochrome c maturation. Proc Natl Acad Sci U S A 2006; 103:4410-5. [PMID: 16537372 PMCID: PMC1400588 DOI: 10.1073/pnas.0600552103] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The covalent attachment of heme cofactors to the apo-polypeptides via thioether bonds is unique to the maturation of c-type cytochromes. A number of thiol-disulfide oxidoreductases prepare the apocytochrome for heme insertion in system I and II cytochrome c maturation. Although most thiol-disulfide oxidoreductases are nonspecific, the less common, specific thiol-disulfide oxidoreductases may be key to directing the usage of electrons. Here we demonstrate that unlike other thiol-disulfide oxidoreductases, the protein responsible for reducing oxidized apocytochrome c in Bacillus subtilis, ResA, is specific for cytochrome c550 and utilizes alternate conformations to recognize redox partners. We report solution NMR evidence that ResA undergoes a redox-dependent conformational change between oxidation states, as well as data showing that ResA utilizes a surface cavity present only in the reduced state to recognize a peptide derived from cytochrome c550. Finally, we confirm that ResA is a specific thiol-disulfide oxidoreductase by comparing its reactivity to our mimetic peptide with its reactivity to oxidized glutathione, a nonspecific substrate. This study biochemically demonstrates the specificity of this thiol-disulfide oxidoreductase and enables us to outline a structural mechanism of regulating the usage of electrons in a thiol-disulfide oxidoreductase system.
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Affiliation(s)
| | - Qiong Wu
- *Biochemistry and
- Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390
| | - Paul J. A. Erbel
- *Biochemistry and
- Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390
| | - Kevin H. Gardner
- *Biochemistry and
- Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390
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10
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Abstract
Redox reactions involving thiol groups in proteins are major participants in cellular redox regulation and antioxidant defense. Although mechanistically similar, thiol-dependent redox processes are catalyzed by structurally distinct families of enzymes, which are difficult to identify by available protein function prediction programs. Herein, we identified a functional motif, CxxS (cysteine separated from serine by two other residues), that was often conserved in redox enzymes, but rarely in other proteins. Analyses of complete Escherichia coli, Campylobacter jejuni, Methanococcus jannaschii, and Saccharomyces cerevisiae genomes revealed a high proportion of proteins known to use the CxxS motif for redox function. This allowed us to make predictions in regard to redox function and identity of redox groups for several proteins whose function previously was not known. Many proteins containing the CxxS motif had a thioredoxin fold, but other structural folds were also present, and CxxS was often located in these proteins upstream of an alpha-helix. Thus, a conserved CxxS sequence followed by an alpha-helix is typically indicative of a redox function and corresponds to thiol-dependent redox sites in proteins. The data also indicate a general approach of genome-wide identification of redox proteins by searching for simple conserved motifs within secondary structure patterns.
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Affiliation(s)
- Dmitri E Fomenko
- Department of Biochemistry, University of Nebraska-Lincoln, 68588-0664, USA
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