Recent insights into copper-containing lytic polysaccharide mono-oxygenases

• Published in: Current opinion in structural biology Vol. 23; no. 5; pp. 660 - 668
• Main Authors: Hemsworth, Glyn R, Davies, Gideon J, Walton, Paul H
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.10.2013
• Subjects: Bacteria - enzymology; Catalytic Domain; Copper - chemistry; Copper - metabolism; Fungi - enzymology; Histidine - metabolism; Methylation; Oxidation-Reduction; Oxygen - chemistry; Oxygen - metabolism; Oxygenases - chemistry; Oxygenases - metabolism; Polysaccharides - metabolism
• ISSN: 0959-440X; 1879-033X
• DOI: 10.1016/j.sbi.2013.05.006

•Recently discovered polysaccharide mono-oxygenases are copper-containing enzymes.•Different sequence families in bacteria and fungi are structurally similar but with subtle differences in active site and mechanism.•Copper active sites use N-terminal histidine to coordinate to copper in the so-called ‘histidine brace’.•Aided by these enzymes, recalcitrant biomass is becoming a viable biofuel source. Recently the role of oxidative enzymes in the degradation of polysaccharides by saprophytic bacteria and fungi was uncovered, challenging the classical model of polysaccharide degradation of being solely via a hydrolytic pathway. 3D structural analyses of lytic polysaccharide mono-oxygenases of both bacterial AA10 (formerly CBM33) and fungal AA9 (formerly GH61) enzymes revealed structures with β-sandwich folds containing an active site with a metal coordinated by an N-terminal histidine. Following some initial confusion about the identity of the metal ion it has now been shown that these enzymes are copper-dependent oxygenases. Here we assess recent developments in the academic literature, focussing on the structures of the copper active sites. We provide critical comparisons with known small-molecules studies of copper–oxygen complexes and with copper methane monoxygenase, another of nature's powerful copper oxygenases.