The Structure of Human Tripeptidyl Peptidase II as Determined by a Hybrid Approach

• Published in: Structure (London) Vol. 20; no. 4; pp. 593 - 603
• Main Authors: Schönegge, Anne-Marie, Villa, Elizabeth, Förster, Friedrich, Hegerl, Reiner, Peters, Jürgen, Baumeister, Wolfgang, Rockel, Beate
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 04.04.2012
• Subjects: Aminopeptidases - chemistry; Aminopeptidases - genetics; Aminopeptidases - metabolism; Cryoelectron Microscopy; Dimers; Dipeptidyl-Peptidases and Tripeptidyl-Peptidases - chemistry; Dipeptidyl-Peptidases and Tripeptidyl-Peptidases - genetics; Dipeptidyl-Peptidases and Tripeptidyl-Peptidases - metabolism; Enzyme Activation; Escherichia coli; Fittings; Holoenzymes - chemistry; Holoenzymes - genetics; Holoenzymes - metabolism; Human; Humans; Hybrid structures; Molecular dynamics; Molecular Dynamics Simulation; Molecular structure; Molecular Weight; Peptides; Protein Multimerization; Protein Structure, Secondary; Protein Structure, Tertiary; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Serine Endopeptidases - chemistry; Serine Endopeptidases - genetics; Serine Endopeptidases - metabolism; Strands
• ISSN: 0969-2126; 1878-4186
• DOI: 10.1016/j.str.2012.01.025

Tripeptidyl-peptidase II (TPPII) is a high molecular mass (∼5 MDa) serine protease, which is thought to act downstream of the 26S proteasome, cleaving peptides released by the latter. Here, the structure of human TPPII (HsTPPII) has been determined to subnanometer resolution by cryoelectron microscopy and single-particle analysis. The complex is built from two strands forming a quasihelical structure harboring a complex system of inner cavities. HsTPPII particles exhibit some polymorphism resulting in complexes consisting of nine or of eight dimers per strand. To obtain deeper insights into the architecture and function of HsTPPII, we have created a pseudoatomic structure of the HsTPPII spindle using a comparative model of HsTPPII dimers and molecular dynamics flexible fitting. Analyses of the resulting hybrid structure of the HsTPPII holocomplex provide new insights into the mechanism of maturation and activation. ► Method for recombinant expression and purification of human TPPII ► 3D map of human TPPII at 9–10 Å resolution by cryo-EM ► Pseudoatomic model of human TPPII by flexible fitting of comparative models ► Dimer-dimer contacts trigger changes in the active site and the entrance to the cavity system