title: Molecular basis for substrate selectivity of a mono- and diacylglycerol lipase from Malassezia globosa.
abstract: The lipase from Malassezia globosa (SMG1) was identified to be strictly specific for mono- and diacylglycerol but not triacylglycerol. The crystal structures of SMG1 were solved in the closed conformation, but they failed to provide direct evidence of factors responsible for this unique selectivity. To address this problem, we constructed a structure in the open, active conformation and modeled a diacylglycerol analogue into the active site. Molecular dynamics simulations were performed on this enzyme-analogue complex to relax steric clashes. This bound diacylglycerol analogue unambiguously identified the position of two pockets which accommodated two alkyl chains of substrate. The structure of SMG1-analogue complex revealed that Leu103 and Phe278 divided the catalytic pocket into two separated moieties, an exposed groove and a narrow tunnel. Analysis of the binding model suggested that the unique selectivity of this lipase mainly resulted from the shape and size of this narrow tunnel, in which there was no space for the settlement of the third chain of triacylglycerol. These results expand our understanding on the mechanism underlying substrate selectivity of enzyme, and could pave the way for site-directed mutagenesis experiments to improve the enzyme for application.
authors: School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China.
authors: Lu
authors: L
authors: Liu
authors: Chongliang
authors: C
authors: Gao
authors: Dongming
authors: D
authors: Lan
authors: Bo
authors: B
authors: Yang
authors: Yonghua
authors: Y
authors: Wang
mesh_terms: D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004075:Diglycerides / Q000737:chemistry; D005656:Fungal Proteins / Q000737:chemistry*; D006860:Hydrogen Bonding; D007930:Leucine / Q000737:chemistry; D008071:Lipoprotein Lipase / Q000737:chemistry*; D008290:Malassezia / Q000201:enzymology*; D056004:Molecular Dynamics Simulation; D008994:Monoacylglycerol Lipases / Q000737:chemistry*; D010649:Phenylalanine / Q000737:chemistry; D013379:Substrate Specificity
chemical_list: D004075:Diglycerides; D005656:Fungal Proteins; D010649:Phenylalanine; D008994:Monoacylglycerol Lipases; D008071:Lipoprotein Lipase; D007930:Leucine