The crystal structure of dipeptidyl peptidase IV (CD26) reveals its functional regulation and enzymatic mechanism.
The membrane-bound glycoprotein dipeptidyl peptidase IV (DP IV, CD26) is a unique multifunctional protein, acting as receptor, binding and proteolytic molecule. We have determined the sequence and 1.8 A crystal structure of native DP IV prepared from porcine kidney. The crystal structure reveals a 2-2-2 symmetric tetrameric assembly which depends on the natively glycosylated beta-propeller blade IV. The crystal structure indicates that tetramerization of DP IV is a key mechanism to regulate its interaction with other components. Each subunit comprises two structural domains, the N-terminal eight-bladed beta-propeller with open Velcro topology and the C-terminal alpha/beta-hydrolase domain. Analogy with the structurally related POP and tricorn protease suggests that substrates access the buried active site through the beta-propeller tunnel while products leave the active site through a separate side exit. A dipeptide mimicking inhibitor complexed to the active site discloses key determinants for substrate recognition, including a Glu-Glu motif that distinguishes DP IV as an aminopeptidase and an oxyanion trap that binds and activates the P(2)-carbonyl oxygen necessary for efficient postproline cleavage. We discuss active and nonactive site-directed inhibition strategies of this pharmaceutical target protein.
Engel
Michael
M
Max-Planck-Institut für Biochemie, Abt. Strukturforschung, D-82152 Martinsried, Germany.
Hoffmann
Torsten
T
Wagner
Leona
L
Wermann
Michael
M
Heiser
Ulrich
U
Kiefersauer
Reiner
R
Huber
Robert
R
Bode
Wolfram
W
Demuth
Hans-Ulrich
HU
Brandstetter
Hans
H
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D018076:DNA, Complementary; D018819:Dipeptidyl Peptidase 4 / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011480:Protease Inhibitors / Q000494:pharmacology; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D013552:Swine
D018076:DNA, Complementary; D011480:Protease Inhibitors; D018819:Dipeptidyl Peptidase 4