Specific Phenylpropanoid Oligomerization in a Neutral Environment by the Recombinant Alkaline Laccase from Paramyrothecium roridum VKM F-3565

TL;DR

A recombinant laccase from a fungus can specifically create phenylpropanoid oligomers in neutral conditions, avoiding unwanted byproducts.

Contribution

A novel recombinant alkaline laccase enables specific phenylpropanoid oligomerization in neutral environments.

Findings

The recombinant laccase achieves specific phenylpropanoid oligomerization in neutral pH.

The enzyme has high N-glycosylation and a molecular weight of 97 kDa.

The laccase is resistant to surfactants and EDTA in neutral conditions.

Abstract

Fungal laccases oxidize a wide range of substrates with a diverse spectrum of subsequent non-specific free radical reactions, leading to the production of unwanted byproducts. This work describes a unique recombinant alkaliphilic laccase from Paramyrothecium roridum VKM F-3565 capable of performing specific oligomerization of phenylpropanoids (precursors of natural lignin and lignans) in a neutral environment, thus preventing the reverse reaction of depolymerization which occurs in an acidic environment. The recombinant alkaliphilic laccase from P. roridum VKM F-3565 with a specific enzyme activity of about 154.0 U/mg (in the reaction with 1 mM ABTS) was obtained using a Komagataella phaffii transformant with a yield of 20 ± 1.5 mg/L. The recombinant laccase had an increased degree of N-glycosylation (MW = 97 kDa), higher pH optimum in reaction with phenylpropanoids and a decreased temperature optimum, compared to the wild-type laccase. The enzyme exhibited great resistance to surfactants and the EDTA in the neutral conditions rather than the acidic ones, whereas its tolerance to mono- and divalent-metal ions was high at acidic conditions. This work demonstrates the important role of N-glycosylation of the alkaliphilic laccase of P. roridum VKM F-3565 in its functional activity. The presence of pH-dependent reactions makes the studied laccase attractive for the phenylpropanoid oligomerization with the production of novel oligomeric phenylpropanoid derivatives for industrial and pharmacological purposes.

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