6Q29

Crystal structure of Laccase from Thermus thermophilus HB27 with an open conformation of beta-hairpin (Average deposted dose 2.5 MGy)

Summary for 6Q29

• Entry DOI: 10.2210/pdb6q29/pdb
• Descriptor: Laccase, TETRAETHYLENE GLYCOL, TRIETHYLENE GLYCOL, ... (5 entities in total)
• Functional Keywords: open loop, multicopper oxidase, structural protein
• Biological source: Thermus thermophilus (strain HB27 / ATCC BAA-163 / DSM 7039)
• Total number of polymer chains: 1
• Total formula weight: 49262.95

Authors

Miranda-Blancas, R.,Rudino-Pinera, E. (deposition date: 2019-08-07, release date: 2020-08-12, Last modification date: 2023-10-11)

Primary citation

Miranda-Blancas, R.,Avelar, M.,Rodriguez-Arteaga, A.,Sinicropi, A.,Rudino-Pinera, E.
The beta-hairpin from the Thermus thermophilus HB27 laccase works as a pH-dependent switch to regulate laccase activity.
J.Struct.Biol., 213:107740-107740, 2021

PubMed 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 and Hg in oxidative conditions, but Cu and Cu are not coordinated in crystallographic experiments, regardless of the redox conditions; however, Ag 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.

PubMed: 33962016
DOI: 10.1016/j.jsb.2021.107740

Experimental method

X-RAY DIFFRACTION (1.702 Å)