Lytic Polysaccharide Monooxygenases: The Microbial Power Tool for Lignocellulose Degradation

Copper-dependent oxidative enzymes named lytic polysaccharide monooxygenases (LPMOs) are important for the degradation of recalcitrant polysaccharides such as cellulose. LPMOs are produced by bacteria, fungi, and viruses. Many microbes that interact with plants have evolved several copies of LPMO-encoding genes. LPMOs require a source of electrons for catalysis, and electrons can –upon exposure to light– be efficiently delivered by light-harvesting pigments. Lytic polysaccharide monooxygenases (LPMOs) are copper-enzymes that catalyze oxidative cleavage of glycosidic bonds. These enzymes are secreted by many microorganisms to initiate infection and degradation processes. In particular, the concept of fungal degradation of lignocellulose has been revised in the light of this recent finding. LPMOs require a source of electrons for activity, and both enzymatic and plant-derived sources have been identified. Importantly, light-induced electron delivery from light-harvesting pigments can efficiently drive LPMO activity. The possible implications of LPMOs in plant–symbiont and –pathogen interactions are discussed in the context of the very powerful oxidative capacity of these enzymes. Lytic polysaccharide monooxygenases (LPMOs) are copper-enzymes that catalyze oxidative cleavage of glycosidic bonds. These enzymes are secreted by many microorganisms to initiate infection and degradation processes. In particular, the concept of fungal degradation of lignocellulose has been revised in the light of this recent finding. LPMOs require a source of electrons for activity, and both enzymatic and plant-derived sources have been identified. Importantly, light-induced electron delivery from light-harvesting pigments can efficiently drive LPMO activity. The possible implications of LPMOs in plant–symbiont and –pathogen interactions are discussed in the context of the very powerful oxidative capacity of these enzymes. Fenton's reagent is a solution of iron or copper and hydrogen peroxide that generates hydroxyl and hydroperoxyl radicals, leading to oxidative destruction of a wide range of organic compounds. a procedure that renders the plant material susceptible to enzymatic degradation. This usually involves cooking under pressure with steam, but alternative methods using ionic liquids, ammonia fiber expansion, or pulping reagents have also been developed. chemically reactive molecules containing oxygen that may result in cell damage when produced in a biological context. Atomic oxygen has two unpaired electrons in its outer electron shell. Examples of ROS include peroxide, superoxide, hydroxyl radical, and singlet oxygen; their electron structures are shown in the figure below.