The beta-hairpin from the Thermus thermophilus HB27 laccase works as a pH-dependent switch to regulate laccase activity
Por:
Miranda-Blancas, R., Avelar, M., Rodriguez-Arteaga, A., Sinicropi, A., Rudiño-Piñera E.
Publicada:
1 jun 2021
Categoría:
Structural biology
Resumen:
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 0-hairpin near the T1Cu site, which is not present in any other
laccases deposited at the PDB. This 0-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 0-hairpin behavior has been analyzed by molecular
dynamics simulations, considering the effect of pH and temperature. The
0-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 0-hairpin. This unique high methionine content of the Tth-MCO
0-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 0-hairpin dynamical behavior could
explain, at least in part, the inefficient laccase activity displayed by
Tth-MCO in acidic pH values.
Filiaciones:
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
Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Siena, 53100, Italy
Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, 2001 Universidad Av., Cuernavaca, Morelos 62210, Mexico
Institute of Chemistry of Organometallic Compounds (CNR-ICCOM), Via Madonna del Piano 10, Sesto Fiorentino, 50019, Italy
CSGI, Consorzio per lo Sviluppo dei Sistemi a Grande Interfase, Sesto Fiorentino, 50019, Italy
|