ABSTRACT
Autophagy is a conserved catabolic process involved in the elimination of proteins, organelles and pathogens. Autophagosome formation is the key process in autophagy. Lipidated Atg8/LC3 proteins that are conjugated to phosphatidylethanolamine (PE) play a key role in autophagosome biogenesis. To understand the function of Atg8/LC3-PE in autophagosome formation and host-pathogen interaction requires preparation and structural manipulation of lipidated Atg8/LC3 proteins. Herein, we report the semisynthesis of LC3 proteins and mutants with modifications of different PE fragments or lipids using native chemical ligation and aminolysis approaches.
Subject(s)
Autophagy-Related Protein 8 Family/chemical synthesis , Microtubule-Associated Proteins/chemical synthesis , Amino Acid Sequence , Autophagy-Related Protein 8 Family/analysis , Kinetics , Maltose-Binding Proteins/metabolism , Microtubule-Associated Proteins/analysis , Phosphatidylethanolamines/chemistry , Spectrometry, Mass, Electrospray IonizationSubject(s)
Autophagy , Microtubule-Associated Proteins/chemistry , Amino Acid Sequence , Circular Dichroism , Detergents/chemistry , Humans , Hydrazines/chemistry , Lysosomes/metabolism , Microtubule-Associated Proteins/chemical synthesis , Microtubule-Associated Proteins/genetics , Microtubule-Associated Proteins/metabolism , Molecular Sequence Data , Peptides/chemical synthesis , Peptides/chemistry , Phosphatidylethanolamines/chemistryABSTRACT
Survivin is a member of the inhibitor of apoptosis protein (IAP) family that blocks cell death by inhibiting the caspase activation pathways. Overexpressed in all common human neoplasms but undetectable in most normal adult tissues, survivin confers tumor resistance to apoptosis and represents an ideal molecular target for therapeutic intervention. How survivin blocks apoptosis, however, has been a subject of intense debate, as evidenced by conflicting reports regarding whether or not survivin can directly bind and inactivate effector caspases. We chemically synthesized large amounts of highly pure human survivin of 142 amino acid residues using native chemical ligation and functionally compared synthetic survivin and a recombinant XIAP--the most intensively studied member of the IAP family. Inhibition assays showed that, while caspase-3 could be effectively inhibited by XIAP, survivin had no detectable inhibitory activity against the enzyme, even at concentrations several thousand-fold higher than XIAP. Our finding supports the premise that survivin does not directly inhibit effector caspases.
