Function and molecular evolution of multicopper blue proteins

Abstract

Multicopper blue proteins (MCBPs) are multidomain proteins that utilize the distinctive redox ability of copper ions. There are a variety of MCBPs that have been roughly classified into three different groups, based on their domain organization and functions: (i) nitrite reductase-type with two domains, (ii) laccase-type with three domains, and (iii) ceruloplasmin-type with six domains. Together, the second and third group are often commonly called multicopper oxidases (MCOs). The rapid accumulation of genome sequence information in recent years has revealed several new types of proteins containing MCBP domains, mainly from bacteria. In this review, the recent research on the functions and structures of MCBPs is summarized, mainly focusing on the new types. The latter half of this review focusses on the two domain MCBPs, which we propose as the evolutionary intermediate of the MCBP family.

Accurate Stabilities of Laccase Mutants Predicted with a Modified FoldX Protocol

“…14 Despite these good trends, average errors typically exceed 1 kcal/mol for ΔΔG, and qualitative predictability (more/less stable) rarely exceeds 90%, although the answer to this simple yes-or-no question is facilitated by the fact that the average, random mutation in any protein is destabilizing by ∼1 kcal/mol. 26 Laccases are multicopper oxidases 27,28 found in plants, bacteria, and fungi, capable of oxidizing a wide range of inorganic 29 and aromatic substrates. 30,31 In fungi, the proteins are extracellularly secreted and must thus be highly stable.…”

“…30,31 In fungi, the proteins are extracellularly secreted and must thus be highly stable. 27 Most laccases have three copper sites (T1, T2, and T3) and three cupredoxin domains and possess very high reduction potentials at the monocopper T1 site that abstracts electrons from substrates. 29 Due to their reactivity and unusual robustness, they are increasingly used in industry, e.g., to degrade lignin for use in second-generation biofuel, 32 for bioremediation of polluted water, 28 or for oxidative bleaching, e.g., of dyes for use in textiles or of pulp in the paper industry.…”

Ultrafast excited-state charge-transfer dynamics in laccase type I copper site

“…In fungal laccases T1 Cu has a planar triangular coordination with the sulfur atom of a cysteine and with the Nδ 1 nitrogen of two histidines, giving rise to a very peculiar trigonal geometry which differs from the tetrahedrically coordinated T1 copper of the other MCOs in which the copper atom is ligated also to a fourth axial ligand (usually a methionine). In fact laccases isolated from fungi possess a leucine or phenylalanine rather than a methionine at the axial position [3,[5][6][7][8], but these amino acids do not contain functional groups that can ligate to the copper atom and their influence on the T1 Cu site is still under debate [9]. The lack of the fourth axial ligand in laccases is considered as an important factor determining the higher values of redox potential displayed by laccases in comparison with the other MCOs [1].…”

“…The lack of the fourth axial ligand in laccases is considered as an important factor determining the higher values of redox potential displayed by laccases in comparison with the other MCOs [1]. The T1 Cu site geometry is responsible for the absorption of the enzyme in the red due to an intense Cys-S to Cu(II) charge-transfer (CT) band, called ligand-to-metal charge transfer (LMCT), with a maximum at about 600 nm [8,11]. In fungal laccases the copper atoms of T2 and T3 sites are arranged in a triangular fashion (forming a trinuclear cluster, TNC), as consistently observed in MCOs, and coordinated to a strongly conserved pattern of four His-X-His motifs.…”

Pushing the limits of automatic computational protein design: design, expression, and characterization of a large synthetic protein based on a fungal laccase scaffold

“…Laccases are multi-copper oxidase enzymes that catalyze the oxidation of a wide range of substrates including phenolics, polyphenolics, aromatic amines, and other compounds with the concomitant reduction of dioxygen to water (Kunamneni et al 2008;Mayer and Staples 2002;Nakamura and Go 2005;Riva 2006;Sakurai and Kataoka 2007;Solomon et al 1996). They have many important industrial applications including: textile and fabric bleaching, lignin degradation for paper production, pollution detoxification, wine clarification, organic chemical synthesis, biosensing and the cathodic reaction in enzymatic biofuel cells.…”