9no3

Publication Abstract from PubMed

The pursuit of sustainable energy has intensified the search for efficient biocatalysts to convert lignocellulosic biomass. In this context, we characterized a novel bifunctional enzyme, TerARA, identified from the gut metagenome of the termite Pseudacanthotermes militaris. Belonging to the glycoside hydrolase 43 (GH43) family, TerARA was heterologously expressed in E. coli BL21 and purified. The enzyme demonstrated bifunctional activity toward synthetic substrates p-nitrophenyl-alpha-L-arabinofuranoside (pNP-Araf) (387.22 +/- 74.2 U/mg) and p-nitrophenyl-beta-D-xylopyranoside (pNP-Xyl) (330.82 +/- 31.2 U/mg), with higher catalytic efficiency for pNP-Araf (9.14 s(-1).mM(-1)), suggesting functional preference as an alpha-L-arabinofuranosidase. Activity modulation by metal ions revealed that Ca(2+) slightly improved efficiency toward pNP-Araf (to 9.58 s(-1).mM(-1) at 1 mM), while Zn(2+) reduced efficiency for pNP-Xyl except at 5 mM (6.65 s(-1).mM(-1)). Zn(2+) also enhanced enzymatic stability, maintaining 80 % activity in pNP-Xyl hydrolysis. Crystallographic analysis at 2.0 A resolution revealed a 43 Glycosyl Hydrolase catalytic domain with a five-bladed beta-propeller fold and two Ca(2+) ions and a Carbohydrate-Binding Module (CBM) domain with a beta-sandwich fold likely involved in substrate interaction. Conserved catalytic residues, binding sites, and Ca(2+) stabilizing effects were identified. TerARA's bifunctionality and structural features support its application in hemicellulose degradation and biomass conversion.

Structural and functional characterization of a bifunctional GH43 alpha-L-arabinofuranosidase/beta-xylosidase from the metagenome of Pseudacanthotermes militaris gut.,Gomes BM, de Oliveira GS, de Melo VS, de Oliveira Rossini N, Adriani PP, Dias MVB, Chambergo FS Int J Biol Macromol. 2025 Sep 24:147909. doi: 10.1016/j.ijbiomac.2025.147909. PMID:41005405^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.