A screening method for polyester films-degrading microorganisms and enzymes.

Enzymatic degradation of plastic pollution offers a promising environmentally friendly waste management strategy, however, suitable biocatalysts must be screened and developed. Traditional screening methods using soluble or solubilised polymers do not necessarily identify enzymes that are effective against solid or crystalline polymers. This study presents a simple, time-saving and cost-effective method for identifying microorganisms and enzymes capable of degrading polymeric films.

Conversion of β-1,6-Glucans to Gentiobiose using an endo-β-1,6-Glucanase PsGly30A from Paenibacillus sp. GKG.

A plethora of di- and oligosaccharides isolated from the natural sources are used in food and pharmaceutical industry. An enzymatic hydrolysis of fungal cell wall β-glucans is a good alternative to produce the desired oligosaccharides with different functionalities, such as the flavour enhancer gentiobiose. We have previously identified PsGly30A as a potential yeast cell wall degrading β-1,6-glycosidase.

Cytidine deaminases catalyze the conversion of (,)-substituted pyrimidine nucleosides.

Cytidine deaminases (CDAs) catalyze the hydrolytic deamination of cytidine and 2'-deoxycytidine to uridine and 2'-deoxyuridine. Here, we report that prokaryotic homo-tetrameric CDAs catalyze the nucleophilic substitution at the fourth position of -acyl-cytidines, -alkyl-cytidines, and -alkyloxycarbonyl-cytidines, and -alkylthio-uridines and -alkyl-uridines, converting them to uridine and corresponding amide, amine, carbamate, thiol, or alcohol as leaving groups. The x-ray structure of a metagenomic CDA_F14 and the molecular modeling of the CDAs used in this study show a relationship between the bulkiness of a leaving group and the volume of the binding pocket, which is partly determined by the flexible β3α3 loop of CDAs.

YqfB protein from Escherichia coli: an atypical amidohydrolase active towards N-acylcytosine derivatives.

Human activating signal cointegrator homology (ASCH) domain-containing proteins are widespread and diverse but, at present, the vast majority of those proteins have no function assigned to them. This study demonstrates that the 103-amino acid Escherichia coli protein YqfB, previously identified as hypothetical, is a unique ASCH domain-containing amidohydrolase responsible for the catabolism of N-acetylcytidine (ac4C). YqfB has several interesting and unique features: i) it is the smallest monomeric amidohydrolase described to date, ii) it is active towards structurally different N-acylated cytosines/cytidines, and iii) it has a high specificity for these substrates (k/K up to 2.

Application of the uridine auxotrophic host and synthetic nucleosides for a rapid selection of hydrolases from metagenomic libraries.

A high-throughput method (≥ 10 of clones can be analysed on a single agar plate) for the selection of ester-hydrolysing enzymes was developed based on the uridine auxotrophy of Escherichia coli strain DH10B ΔpyrFEC and the acylated derivatives 2',3',5'-O-tri-acetyluridine and 2',3',5'-O-tri-hexanoyluridine as the sole source of uridine. The proposed approach permits the selection of hydrolases belonging to different families and active towards different substrates. Moreover, the ester group of the substrate used for the selection, at least partly, determined the specificity of the selected enzymes.