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Miranda-Blancas R, Avelar M, Rodriguez-Arteaga A, Sinicropi A, Rudiño-Piñera E. The β-hairpin from the Thermus thermophilus HB27 laccase works as a pH-dependent switch to regulate laccase activity. J Struct Biol 2021; 213:107740. [PMID: 33962016 DOI: 10.1016/j.jsb.2021.107740] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 04/30/2021] [Accepted: 04/30/2021] [Indexed: 11/29/2022]
Abstract
The multi-copper oxidase from the hyper-thermophilic bacteria Thermus thermophilus (Tth-MCO), has been previously characterized and described as an example of a laccase with low catalytic properties, especially when it is compared with the activity of fungal laccases, but it is active at high temperatures. Structurally, Tth-MCO has a unique feature: a β-hairpin near the T1Cu site, which is not present in any other laccases deposited at the PDB. This β-hairpin has an expected crystallographic behavior in solvent-exposed areas of a crystallized protein: lack of electron density, high B-values and several crystalline contacts with neighboring crystallographic copies; however, its dynamical behavior in solution and its biological implications have not been described. Here, we describe four new Tth-MCO crystallographic structures, and the β-hairpin behavior has been analyzed by molecular dynamics simulations, considering the effect of pH and temperature. The β-hairpin new crystallographic conformations described here, together with their dynamics, were used to understand the pH-restrained laccase activity of Tth-MCO against substrates as syringaldazine. Remarkably, there are insertions in laccases from Thermus and Meiothermus genus, sharing the same position and a methionine-rich composition of the Tth-MCO β-hairpin. This unique high methionine content of the Tth-MCO β-hairpin is responsible to coordinate, Ag+1 and Hg+1 in oxidative conditions, but Cu+1 and Cu+2 are not coordinated in crystallographic experiments, regardless of the redox conditions; however, Ag+1 addition does not affect Tth-MCO laccase activity against syringaldazine. Here, we propose that the pH-dependent β-hairpin dynamical behavior could explain, at least in part, the inefficient laccase activity displayed by Tth-MCO in acidic pH values.
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Affiliation(s)
- R Miranda-Blancas
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, 2001 Universidad Av., Cuernavaca, Morelos 62210, Mexico; Instituto de Investigación en Dinámica Celular, Universidad Autónoma del Estado de Morelos, 1001 Universidad Av., Cuernavaca, Morelos 62209, Mexico
| | - M Avelar
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, 53100 Siena, Italy
| | - A Rodriguez-Arteaga
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, 2001 Universidad Av., Cuernavaca, Morelos 62210, Mexico
| | - A Sinicropi
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, 53100 Siena, Italy; Institute of Chemistry of Organometallic Compounds (CNR-ICCOM), Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy; CSGI, Consorzio per lo Sviluppo dei Sistemi a Grande Interfase, 50019 Sesto Fiorentino, Italy
| | - E Rudiño-Piñera
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, 2001 Universidad Av., Cuernavaca, Morelos 62210, Mexico.
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