Title: The Crystal Structures of Thermomyces (Humicola) Lanuginosa Lipase in Complex with Enzymatic Reactants McPherson A, Larson SB, Kalasky A Ref: Curr Enzym Inhib, 16:, 2020 : PubMed
Aim: To understand the details of the action of fungal lipase and the mechanism for its observed interfacial activation.
Background: Fungal lipase, crucial to biotechnology, functions at the lipid - water interface where it undergoes a poorly understood interfacial activation. Biochemical factors influencing its activation and inhibition are also poorly understood. This study provides a basis for its activity and a plausible mechanism for interfacial activation.
Objective: To determine the structures of fungal lipase in different crystal forms in complex with their enzymatic reactants and inhibitors.
Methods: X-ray crystallography.
Results: Thermomyces lanuginosa lipase was visualized in three crystal forms, of space groups H32, P21 and I222 at 1.3 to 1.45 A resolution. Rhombohedral crystals have one molecule, lacking segment 241 to 252, as an asymmetric unit, with molecules organized as two trimers. Monoclinic crystals asymmetric unit is six intact molecules organized as two, nearly identical trimers, each exhibiting an NCS threefold axis. The -Ylid helix was consistently closed. Oligomerization into trimers creates an internal hydrophobic cavity where catalysis occurs. In monoclinic and orthorhombic crystals, active site serines were esterified to fatty acids. Lipase had bound within their trimeric, hydrophobic cavities 1,3-diacylglycerols with fatty acid chain lengths of about 18 carbons.
Conclusion: Results suggest trimers are likely the active form of the enzyme at the lipid - water interface. Formation of trimers may provide an explanation for 'interfacial activation'.
Representative scheme of Lipase_3 structure and an image from PDBsum server
Databases
PDB-Sum
6OR3 Previously Class, Architecture, Topology and Homologous superfamily - PDB-Sum server
FSSP
6OR3Fold classification based on Structure-Structure alignment of Proteins - FSSP server
