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Khosla N, Thayil SM, Kaur R, Kesavan AK. MSMEG_3955 from Mycobacterium smegmatis is a FMN bounded homotrimeric NAD(P)H:Flavin mononucleotide (FMN) oxidoreductase. BMC Microbiol 2021; 21:319. [PMID: 34798816 PMCID: PMC8605562 DOI: 10.1186/s12866-021-02330-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 09/27/2021] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Tuberculosis (TB) remains an important public health problem since it is the major cause of elevated morbidity and mortality globally. Previous works have shown that Mycobacterium tuberculosis (Mtb); the prime causative agent of the deadly disease has dormancy survival regulator (DosR) regulon, a two-component regulatory system which controls the transcription of more than 50 genes. However, the structure and detailed functions of these DosR regulated genes are largely undetermined. Out of many DosR regulon genes, Rv3131 gets up regulated in hypoxic conditions and was believed to encode for a nitroreductase flavoprotein. The utilization of mycobacteria-specific model systems has greatly added to our understanding of the molecular mechanisms involved in the life cycle and pathogenesis of Mtb. RESULTS In this study the non-pathogenic mycobacterial model organism Mycobacterium smegmatis (Msmeg) was used to reveal the structure and function of MSMEG_3955; which is a homologue of Rv3131 from Mtb. Using chromatography and spectroscopy techniques it was revealed that cofactor flavin mononucleotide (FMN) was bound to flavoprotein MSMEG_3955. Consistent with the homology modelling predictions, Circular Dichroism (CD) analysis indicated that the MSMEG_3955 is composed of 39.3% α-helix and 24.9% β-pleated sheets. In contrast to the current notions, the enzymatic assays performed in the present study revealed that MSMEG_3955 was not capable of reducing nitro substrates but showed NADPH dependent FMN oxidoreductase activity. Also, gel permeation chromatography, dynamic light scattering and native acidic gels showed that MSMEG_3955 exists as a homotrimer. Furthermore, the presence of NADPH dependent FMN oxidoreductase and homotrimeric existence could be an alternative function of the protein to help the bacteria survive in dormant state or may be involved in other biochemical pathways. CONCLUSION MSMEG_3955 is a FMN bound flavoprotein, which exits as a trimer under in vitro conditions. There is no disulphide linkages in between the three protomers of the homotrimer MSMEG_3955. It has a NADPH dependent FMN oxidoreductase activity.
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Affiliation(s)
- Neha Khosla
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar, Punjab, 143005, India
| | - Seema Madhumal Thayil
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar, Punjab, 143005, India
| | - Rajinder Kaur
- Department of Botanical and Environmental Sciences, Guru Nanak Dev University, Amritsar, Punjab, 143005, India
| | - Anup Kumar Kesavan
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar, Punjab, 143005, India.
- Current Address: Department of Biotechnology & Microbiology, Kannur University, Dr. E.K. Janaki Ammal Campus, Palayad, Thalassery, Kannur, Kerala, India.
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Schwarz MGA, Luzes BGC, Correa PR, da Silva-Gonçalves AJ, Machado LDA, Guimarães ACR, Mendonça-Lima L. M. bovis BCG Moreau N-Terminal Loss Leads to a Less Stable Dodecin With Lower Flavin Binding Capacity. Front Cell Infect Microbiol 2021; 11:658888. [PMID: 33869088 PMCID: PMC8044443 DOI: 10.3389/fcimb.2021.658888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 03/12/2021] [Indexed: 11/17/2022] Open
Abstract
Tuberculosis still remains a concerning health problem worldwide. Its etiologic agent, Mycobacterium tuberculosis, continues to be the focus of research to unravel new prophylactic and therapeutic strategies against this disease. The only vaccine in use against tuberculosis is based on the in vitro attenuated strain, M. bovis BCG. Dodecin is a dodecameric complex important for flavin homeostasis in Archea and Eubacteria, and the M. tuberculosis protein is described as thermo- and halostable. M. bovis BCG Moreau, the Brazilian vaccine strain, has a single nucleotide polymorphism in the dodecin start codon, leading to a predicted loss of seven amino acids at the protein N-terminal end. In this work we aimed to characterize the effect of this mutation in the BCG Moreau protein features. Our recombinant protein assays show that the predicted BCG homolog is less thermostable than M.tb’s but maintains its dodecamerization ability, although with a lower riboflavin-binding capacity. These data are corroborated by structural analysis after comparative modeling, showing that the predicted BCG dodecin complex has a lower interaction energy among its monomers and also a distinct electrostatic surface near the flavin binding pocket. However, western blotting assays with the native proteins were unable to detect significant differences between the BCG Moreau and M.tb orthologs, indicating that other factors may be modulating protein structure/function in the bacterial context.
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Affiliation(s)
| | | | - Paloma Rezende Correa
- Laboratório de Genômica Funcional e Bioinformática, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
| | | | - Lucas de Almeida Machado
- Laboratório de Genômica Funcional e Bioinformática, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
| | | | - Leila Mendonça-Lima
- Laboratório de Genômica Funcional e Bioinformática, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
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Bourdeaux F, Kopp Y, Lautenschläger J, Gößner I, Besir H, Vabulas RM, Grininger M. Dodecin as carrier protein for immunizations and bioengineering applications. Sci Rep 2020; 10:13297. [PMID: 32764653 PMCID: PMC7414021 DOI: 10.1038/s41598-020-69990-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 07/13/2020] [Indexed: 11/29/2022] Open
Abstract
In bioengineering, scaffold proteins have been increasingly used to recruit molecules to parts of a cell, or to enhance the efficacy of biosynthetic or signalling pathways. For example, scaffolds can be used to make weak or non-immunogenic small molecules immunogenic by attaching them to the scaffold, in this role called carrier. Here, we present the dodecin from Mycobacterium tuberculosis (mtDod) as a new scaffold protein. MtDod is a homododecameric complex of spherical shape, high stability and robust assembly, which allows the attachment of cargo at its surface. We show that mtDod, either directly loaded with cargo or equipped with domains for non-covalent and covalent loading of cargo, can be produced recombinantly in high quantity and quality in Escherichia coli. Fusions of mtDod with proteins of up to four times the size of mtDod, e.g. with monomeric superfolder green fluorescent protein creating a 437 kDa large dodecamer, were successfully purified, showing mtDod's ability to function as recruitment hub. Further, mtDod equipped with SYNZIP and SpyCatcher domains for post-translational recruitment of cargo was prepared of which the mtDod/SpyCatcher system proved to be particularly useful. In a case study, we finally show that mtDod-peptide fusions allow producing antibodies against human heat shock proteins and the C-terminus of heat shock cognate 70 interacting protein (CHIP).
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Affiliation(s)
- Florian Bourdeaux
- Institute of Organic Chemistry and Chemical Biology, Buchmann Institute for Molecular Life Sciences, Cluster of Excellence for Macromolecular Complexes, Goethe University Frankfurt, Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany
| | - Yannick Kopp
- Institute of Biophysical Chemistry, Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Max-von-Lauer Str. 15, 60438, Frankfurt am Main, Germany
| | - Julia Lautenschläger
- Institute of Organic Chemistry and Chemical Biology, Buchmann Institute for Molecular Life Sciences, Cluster of Excellence for Macromolecular Complexes, Goethe University Frankfurt, Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany
| | - Ines Gößner
- Institute of Organic Chemistry and Chemical Biology, Buchmann Institute for Molecular Life Sciences, Cluster of Excellence for Macromolecular Complexes, Goethe University Frankfurt, Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany
| | - Hüseyin Besir
- European Molecular Biology Laboratory, 69117, Heidelberg, Germany
- PROGEN Biotechnik GmbH, 69123, Heidelberg, Germany
| | - R Martin Vabulas
- Institute of Biochemistry, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Martin Grininger
- Institute of Organic Chemistry and Chemical Biology, Buchmann Institute for Molecular Life Sciences, Cluster of Excellence for Macromolecular Complexes, Goethe University Frankfurt, Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany.
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