Syntheses and Activities of the Functional Structures of a Glycolipid Essential for Membrane Protein Integration
Year: 2018
Type: article
Abstract: MPIase is the first known glycolipid that is essential for membrane protein integration in the inner membrane of E. coli. Since the amount of natural MPIase available for analysis is limited and it contains structural heterogeneity, precisely designed synthetic derivatives are promising tools for further elucidation of its membrane protein integration mechanism. Thus, we synthesized the minimal unit of MPIase, a trisaccharyl pyrophospholipid termed mini-MPIase-3, and its derivatives. Integration assays revealed that the chemically synthesized trisaccharyl pyrophospholipid possesses significant activity, indicating that it includes the essential structure for membrane integration. Structure-activity relationship studies demonstrated that the number of trisaccharide units and the 6- O-acetyl group on N-acetylglucosamine contribute to efficient integration. Furthermore, anchoring in the membrane by a lipid moiety was essential for the integration. However, the addition of phosphorylated glycans devoid of the lipid moiety in the assay solution modulated the integration activity of MPIase embedded in liposomes, suggesting an interaction between phosphorylated glycans and substrate proteins in aqueous solutions. The prevention of protein aggregation required the 6- O-acetyl group on N-acetylglucosamine, a phosphate group at the reducing end of the glycan, and a long glycan chain. Taken together, we verified the mechanism of the initial step of the translocon-independent pathway in which a membrane protein is captured by a glycan of MPIase, which maintains its structure to be competent for integration, and then MPIase integrates it into the membrane by hydrophobic interactions with membrane lipids.
Source: ACS Chemical Biology
Institutions: Suntory Foundation for Life Sciences, Iwate University
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Awards: Elucidation of the process of membrane protein insrtion and folding., Structure and function of glycolipozyme MPIase involved in protein translocation across and insertion into membranes, G2166001220, G2954224718, Structure and function of glycolipozyme MPIase, involved in protein translocation across and integration into membranes, Overproduction of functional membrane proteins by improvement of integration factors of E. coli, G4074900042, Elucidation of membrane protein integration mechanism of glycolipid MPIase by using synthetic MPIase library., Mechanism Analysis of Interaction between Membrane and a Glycolipid Essential for Membrane Protein Integration, G5021263372, Synthesis of partial structure of glycolipid MPIase for elucidating the mechanism on membrane protein integration in the inner membrane of E. coli., Building biomembranes using E. coli membranes as a model system, Elucidation of Mechanisms on Membrane Protein Integration by a Glycolipid Acting Like an Enzyme, G7089666372, Function and structure of novel glycolipid essential for membrane protein integration
OpenAlex ID: W2887022166