A giant protease with a twist: the TPP II complex from Drosophila studied by electron microscopy.
Tripeptidyl peptidase II (TPP II) is an exopeptidase of the subtilisin type of serine proteases that is thought to act downstream of the proteasome in the ubiquitin-proteasome pathway. Recently, a key role in a pathway parallel to the ubiquitin-proteasome pathway has been ascribed to TPP II, which forms a giant protease complex in mammalian cells. Here, we report the 900-fold purification of TPP II from Drosophila eggs and demonstrate via cryo-electron microscopy that TPP II from Drosophila melanogaster also forms a giant protease complex. The presented three-dimensional reconstruction of the 57 x 27 nm TPP II complex at 3.3 nm resolution reveals that the 150 kDa subunits form a superstructure composed of two segmented and twisted strands. Each strand is 12.5 nm in width and composed of 11 segments that enclose a central channel.
Rockel
Beate
B
Life Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA.
Peters
Jürgen
J
Kühlmorgen
Brigitte
B
Glaeser
Robert M
RM
Baumeister
Wolfgang
W
D000626:Aminopeptidases; D000818:Animals; D020285:Cryoelectron Microscopy; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D029721:Drosophila Proteins / Q000737:chemistry / Q000648:ultrastructure*; D004527:Egg Proteins / Q000737:chemistry / Q000648:ultrastructure; D007091:Image Processing, Computer-Assisted; D046911:Macromolecular Substances; D008958:Models, Molecular; D011487:Protein Conformation; D012697:Serine Endopeptidases / Q000737:chemistry / Q000648:ultrastructure*
D029721:Drosophila Proteins; D004527:Egg Proteins; D046911:Macromolecular Substances; D000626:Aminopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C048001:tripeptidyl-peptidase 2; D012697:Serine Endopeptidases