A comparative structural analysis of the surface properties of asco-laccases

Abstract

Laccases of different biological origins have been widely investigated and these studies have elucidated fundamentals of the generic catalytic mechanism. However, other features such as surface properties and residues located away from the catalytic centres may also have impact on enzyme function. Here we present the crystal structure of laccase from Myceliophthora thermophila (MtL) to a resolution of 1.62 Å together with a thorough structural comparison with other members of the CAZy family AA1_3 that comprises fungal laccases from ascomycetes. The recombinant protein produced in A. oryzae has a molecular mass of 75 kDa, a pI of 4.2 and carries 13.5 kDa N-linked glycans. In the crystal, MtL forms a dimer with the phenolic substrate binding pocket blocked, suggesting that the active form of the enzyme is monomeric. Overall, the MtL structure conforms with the canonical fold of fungal laccases as well as the features specific for the asco-laccases. However, the structural comparisons also reveal significant variations within this taxonomic subgroup. Notable differences in the T1-Cu active site topology and polar motifs imply molecular evolution to serve different functional roles. Very few surface residues are conserved and it is noticeable that they encompass residues that interact with the N-glycans and/or are located at domain interfaces. The N-glycosylation sites are surprisingly conserved among asco-laccases and in most cases the glycan displays extensive interactions with the protein. In particular, the glycans at Asn88 and Asn210 appear to have evolved as an integral part of the asco-laccase structure. An uneven distribution of the carbohydrates around the enzyme give unique properties to a distinct part of the surface of the asco-laccases which may have implication for laccase function–in particular towards large substrates.

Laccases: structure, function, and potential application in water bioremediation

“…These references show the complexity and subtlety of the reaction pathway through enzyme structure. This mechanism involves a substrate binding pocket [154, 156], which confers selectivity by proper docking, and also affects the E ° by induced fitting to the active site. There, the T1 copper atom extracts an electron from the substrate, followed by a relay of protein functional groups, namely thiol, carbonyl, and imidazole groups, which transfer that electron through the trinuclear cluster, where they are gathered until four electrons are collected.…”

Applications of Microbial Laccases: Patent Review of the Past Decade (2009–2019)

“…Laccases with non-coordinating residues at this position generally have higher E 0 , and they are thus capable of oxidizing a wider array of substrates [33]. For example, high E 0 basidiomycete laccases (0.5-0.8 V versus NHE) usually have a Phe, and medium E 0 ascomycete laccases (0.4-0.7 V versus NHE) have Leu [27,33]. However, this observation is not to be taken as a general rule, since for example, the M. thermophila laccase, containing Leu in this position, has still a lower E 0 than B. subtilis CotA laccase [34].…”

Calcium Chloride (CaCl2) : Characteristics and Molecular Interaction in Solution

“…Kalsium klorida ini memiliki sifat fisika (124) dan juga sifat kimia (221), diantarnya : Tabel 3. Sifat Fisika dan Sifat Kimia Kalsium Klorida (125)(126)(127)(128)(129)(130)(131)(132)(133)(134) https://id.wikipedia.org/wiki/Kalsium_klorida Optimasi (212) Molekul CaCl 2 menggunakan Molecular Mechanic (MM2) Optimasi (137) molekul CaCl 2 dilakukan dengan Molekular Mekanik (MM2) dan menghasilkan output data dalam bentuk data geometri (239) atom atom dalam molekul dan Energi optimumnya. Hasil output yang diolah dapat dilihat sebagai berikut :…”