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Barreiro DS, Oliveira RNS, Pauleta SR. Biochemical Characterization of the Copper Nitrite Reductase from Neisseria gonorrhoeae. Biomolecules 2023; 13:1215. [PMID: 37627281 PMCID: PMC10452240 DOI: 10.3390/biom13081215] [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: 06/17/2023] [Revised: 07/16/2023] [Accepted: 08/02/2023] [Indexed: 08/27/2023] Open
Abstract
The copper-containing nitrite reductase from Neisseria gonorrhoeae has been shown to play a critical role in the infection mechanism of this microorganism by producing NO and abolishing epithelial exfoliation. This enzyme is a trimer with a type 1 copper center per subunit and a type 2 copper center in the subunits interface, with the latter being the catalytic site. The two centers were characterized for the first time by EPR and CD spectroscopy, showing that the type 1 copper center has a high rhombicity due to its lower symmetry and more tetragonal structure, while the type 2 copper center has the usual properties, but with a smaller hyperfine coupling constant (A// = 10.5 mT). The thermostability of the enzyme was analyzed by differential scanning calorimetry, which shows a single endothermic transition in the thermogram, with a maximum at 94 °C, while the CD spectra in the visible region indicate the presence of the type 1 copper center up to 80 °C. The reoxidation of the N. gonorrhoeae copper-containing nitrite reductase in the presence of nitrite were analyzed by visible spectroscopy and showed a pH dependence, being higher at pH 5.5-6.0. The high thermostability of this enzyme may be important to maintaining a high activity in the extracellular space and to making it less susceptible to denaturation and proteolysis, contributing to the proliferation of N. gonorrhoeae.
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Affiliation(s)
- Daniela S. Barreiro
- Microbial Stress Lab, UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - Ricardo N. S. Oliveira
- Microbial Stress Lab, UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - Sofia R. Pauleta
- Microbial Stress Lab, UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
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Duré AB, Cristaldi JC, Guevara Cuasapud LA, Dalosto SD, Rivas MG, Ferroni FM, González PJ, Montich GG, Brondino CD. Molecular and kinetic properties of copper nitrite reductase from Sinorhizobium meliloti 2011 upon substituting the interfacial histidine ligand coordinated to the type 2 copper active site for glycine. J Inorg Biochem 2023; 241:112155. [PMID: 36739731 DOI: 10.1016/j.jinorgbio.2023.112155] [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: 11/22/2022] [Revised: 01/25/2023] [Accepted: 01/28/2023] [Indexed: 02/05/2023]
Abstract
A copper-containing nitrite reductase catalyzes the reduction of nitrite to nitric oxide in the denitrifier Sinorhizobium meliloti 2011 (SmNirK), a microorganism used as bioinoculant in alfalfa seeds. Wild type SmNirK is a homotrimer that contains two copper centers per monomer, one of type 1 (T1) and other of type 2 (T2). T2 is at the interface of two monomers in a distorted square pyramidal coordination bonded to a water molecule and three histidine side chains, H171 and H136 from one monomer and H342 from the other. We report the molecular, catalytic, and spectroscopic properties of the SmNirK variant H342G, in which the interfacial H342 T2 ligand is substituted for glycine. The molecular properties of H342G are similar to those of wild type SmNirK. Fluorescence-based thermal shift assays and FTIR studies showed that the structural effect of the mutation is only marginal. However, the kinetic reaction with the physiological electron donor was significantly affected, which showed a ∼ 100-fold lower turnover number compared to the wild type enzyme. UV-Vis, EPR and FTIR studies complemented with computational calculations indicated that the drop in enzyme activity are mainly due to the void generated in the protein substrate channel by the point mutation. The main structural changes involve the filling of the void with water molecules, the direct coordination to T2 copper ion of the second sphere aspartic acid ligand, a key residue in catalysis and nitrite sensing in NirK, and to the loss of the 3 N-O coordination of T2.
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Affiliation(s)
- Andrea B Duré
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral and CONICET, S3000ZAA, Santa Fe, Argentina
| | - Julio C Cristaldi
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral and CONICET, S3000ZAA, Santa Fe, Argentina; Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende 5000, Córdoba, Argentina; Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Lorieth A Guevara Cuasapud
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral and CONICET, S3000ZAA, Santa Fe, Argentina
| | - Sergio D Dalosto
- Instituto de Física del Litoral, CONICET-UNL, Güemes 3450, S3000GLN, Santa Fe, Argentina
| | - María Gabriela Rivas
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral and CONICET, S3000ZAA, Santa Fe, Argentina
| | - Felix M Ferroni
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral and CONICET, S3000ZAA, Santa Fe, Argentina
| | - Pablo J González
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral and CONICET, S3000ZAA, Santa Fe, Argentina
| | - Guillermo G Montich
- Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende 5000, Córdoba, Argentina; Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina.
| | - Carlos D Brondino
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral and CONICET, S3000ZAA, Santa Fe, Argentina.
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Ramírez CS, Tolmie C, Opperman DJ, González PJ, Rivas MG, Brondino CD, Ferroni FM. Copper nitrite reductase from Sinorhizobium meliloti 2011: Crystal structure and interaction with the physiological versus a nonmetabolically related cupredoxin-like mediator. Protein Sci 2021; 30:2310-2323. [PMID: 34562300 DOI: 10.1002/pro.4195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 09/23/2021] [Accepted: 09/24/2021] [Indexed: 11/08/2022]
Abstract
We report the crystal structure of the copper-containing nitrite reductase (NirK) from the Gram-negative bacterium Sinorhizobium meliloti 2011 (Sm), together with complex structural alignment and docking studies with both non-cognate and the physiologically related pseudoazurins, SmPaz1 and SmPaz2, respectively. S. meliloti is a rhizobacterium used for the formulation of Medicago sativa bionoculants, and SmNirK plays a key role in this symbiosis through the denitrification pathway. The structure of SmNirK, solved at a resolution of 2.5 Å, showed a striking resemblance with the overall structure of the well-known Class I NirKs composed of two Greek key β-barrel domains. The activity of SmNirK is ~12% of the activity reported for classical NirKs, which could be attributed to several factors such as subtle structural differences in the secondary proton channel, solvent accessibility of the substrate channel, and that the denitrifying activity has to be finely regulated within the endosymbiont. In vitro kinetics performed in homogenous and heterogeneous media showed that both SmPaz1 and SmPaz2, which are coded in different regions of the genome, donate electrons to SmNirK with similar performance. Even though the energetics of the interprotein electron transfer (ET) process is not favorable with either electron donors, adduct formation mediated by conserved residues allows minimizing the distance between the copper centers involved in the interprotein ET process.
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Affiliation(s)
- Cintia Soledad Ramírez
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral (UNL). CONICET, Ciudad Universitaria, Santa Fe, Argentina
| | - Carmien Tolmie
- Department of Microbiology and Biochemistry, University of the Free State (UFS), Bloemfontein, South Africa
| | - Diederik Johannes Opperman
- Department of Microbiology and Biochemistry, University of the Free State (UFS), Bloemfontein, South Africa
| | - Pablo Javier González
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral (UNL). CONICET, Ciudad Universitaria, Santa Fe, Argentina
| | - María Gabriela Rivas
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral (UNL). CONICET, Ciudad Universitaria, Santa Fe, Argentina
| | - Carlos Dante Brondino
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral (UNL). CONICET, Ciudad Universitaria, Santa Fe, Argentina
| | - Felix Martín Ferroni
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral (UNL). CONICET, Ciudad Universitaria, Santa Fe, Argentina
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